ESIT 2024: Gathering of Global Minds to Hangzhou for Cutting-Edge Infrared and Terahertz Innovation
Welcome to our new Editorial Board Members Prof. Manijeh Razeghi
Welcome to our new Editorial Board Members Dr. He Zhiping
Welcome to our new Editorial Board Members Dr. Jun Ge
Welcome to our new Editorial Board Members Dr. Ye Zhenhua
Welcome to our new Editorial Board Members Dr. Chen Fansheng
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LI Chong, MA Zi-Yi, YANG Shuai, LIU Yue-Wen, WANG Jia-Xuan, LIU Yun-Fei, DONG Yu-Sen, LI Zi-Qian, LIU Dian-Bo
2025,44(3):327-334 ,DOI: 10.11972/j.issn.1001-9014.2025.03.001
Abstract:
This paper investigates the punch-through characteristics of separate absorption， charge and multiplication avalanche photodetector （SACM APD）. By analyzing the device''s spectral response， capacitance characteristics， and I-V characteristics at various operating temperatures， and combining these with simulated internal electric field and energy band distributions from the SILVACO platform， we analyzed examined the performance of the SACM APD before and after punch-through and established a corresponding mathematical model. Through structural and process parameter optimization for silicon-based SACM APD devices， simulations revealed that when the ion implantation energy of the field-control layer was 580 keV， the optimized device exhibited a punch-through threshold voltage of -30 V and a capacitance reduction to one-third of the pre-punch-through value. Subsequently， a silicon SACM APD device was fabricated using the complementary metal-oxide-semiconductor （CMOS） process. Measurements confirmed a punch-through threshold voltage of -30 V， a 2.18-fold increase in photocurrent at 808 nm （punch-through）， a redshift of the peak responsivity wavelength from 590 nm （pre-punch-through） to 820 nm （post-punch-through）， and an elevation of the peak responsivity from 0.171 A/W@590 nm to 0.377 A/W@820 nm. The capacitance was also reduced to one-third of the pre-punch-through value at 1 MHz.
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NIE Su-Zhen, CAO Jie, HAO Qun, ZHUANG Xu-Ye
2025,44(3):335-344 ,DOI: 10.11972/j.issn.1001-9014.2025.03.002
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Unmanned Aerial Vehicles（UAVs） have a wide range of applications in agriculture， logistics， rescue and disaster relief because of their compactness， lightness and flexibility. However， if they are used improperly or mismanaged， they may not only cause personal privacy leakage and property loss， but also pose a threat to public safety and even military security. Therefore， real-time and accurate detection and warning of UAVs in the airspace play an important role. In this regard， a multi-channel interactive attention mechanism and edge contour enhancement （MCIAECE） method for infrared UAV detection is proposed. Firstly， the shallow and deep features of the infrared image are extracted by a dual-channel consisting of a multi-channel interactive attention mechanism module and an edge contour enhancement module， after which the attention mechanism enhances the target features while the edge contour enhancement obtains more detailed information. Then the extracted features of each layer are fused and enhanced using the multilevel feature fusion module to obtain the detection results. The experimental results show that better results can be achieved with the MCIAECE method on all three datasets. Among them， the best results are obtained on the NUDT-SIRST infrared dataset， with the detection probability and intersection over union of 98.83% and 85.11% respectively， which increased by 1.95% and 6.88% compared to the baseline network，and the effect is significant in the edge contour restoration of the target compared with other methods.
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Abbas Haddadi, Gail Brown, Manijeh Razeghi
2025,44(3):345-350 ,DOI: 10.11972/j.issn.1001-9014.2025.03.003
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This study introduces a comprehensive theoretical framework for accurately calculating the electronic band-structure of strained long-wavelength InAs/GaSb type-II superlattices. Utilizing an eight-band
Hamiltonian in conjunction with a scattering matrix method， the model effectively incorporates quantum confinement， strain effects， and interface states. This robust and numerically stable approach achieves exceptional agreement with experimental data， offering a reliable tool for analyzing and engineering the band structure of complex multilayer systems. - 1
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ZHU Xiao-Jun, LIU Yu, WU Yue, ZHUANG Hao-Ran, SUN Dan, SHI Yue-Chun, CAO Juan, YANG Yong-Jie
2025,44(3):351-356 ,DOI: 10.11972/j.issn.1001-9014.2025.03.004
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A novel near-infrared all-fiber mode monitor based on a mini-two-path Mach-Zehnder interferometer （MTP-MZI） is proposed. The MTP-MZI mode monitor is created by fusing a section of （no-core fiber ，NCF） and a （single-mode fiber ，SMF） together with an optical fiber fusion splicer， establishing two distinct centimeter-level optical transmission paths. Since the high-order modes in NCF transmit near-infrared light more sensitively to curvature-induced energy leakage than the fundamental mode in SMF， the near-infrared high-order mode light leaks out of NCF when the curvature changes， causing the MTP-MZI transmission spectrum to change. By analyzing the relationship between the curvature， transmission spectrum， and spatial frequency spectrum， the modes involved in the interference can be studied， thereby revealing the mode transmission characteristics of near-infrared light in optical fibers. In the verification experiments， higher-order modes were excited by inserting a novel hollow-core fiber （HCF） into the MTP-MZI. When the curvature of the MTP-MZI changes， the near-infrared light high-order mode introduced into the device leaks out， causing the transmission spectrum to return to its original state before bending and before the HCF was spliced. The experimental results demonstrate that the MTP-MZI mode monitor can monitor the fiber modes introduced from the external environment， providing both theoretical and experimental foundations for near-infrared all-fiber mode monitoring in optical information systems.
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DU Hai-Wei, WANG Jing-Yi, SUN Chang-Ming, LI Qiang-Shuang
2025,44(3):357-363 ,DOI: 10.11972/j.issn.1001-9014.2025.03.005
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Electro-Optic Sampling （EOS） detection technique has been widely used in terahertz science and technology， and it also can measure the field time waveform of the few-cycle laser pulse. Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse. Here， we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle laser pulse. The shift of the central frequency and change of the bandwidth induced by the EOS detection are calculated， and then the pulse distortions induced in this detection process are discussed. It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth. These changings decrease when the laser wavelength increases from 2 μm to 10 μm. This work can help to estimate the performance of the EOS detection technique in the mid-infrared band and offer a reference for the related experiment as well.
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SONG Jian-Tao, MA Shu-Huan, WANG Chen-Xiao, YANG Fan, CHEN Zhi-Jian, YAO Bi-Mu
2025,44(3):364-369 ,DOI: 10.11972/j.issn.1001-9014.2025.03.006
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To enhance the net photoelectric conversion efficiency of quantum well infrared photodetectors， this study investigates the matching conditions between radiative dissipation and coupling strength in devices operating in the strong light-matter coupling regime. A critical coupling model distinct from the conventional intrinsic and radiative dissipation matching is proposed. Through an analytical model， the contributions of intrinsic thermal dissipation and coupling strength to the critical conditions are quantified. The results indicate that， with optimized matching parameters， the net photoelectric absorption efficiency， excluding thermal dissipation， can exceed 95%. Moreover， under the synergistic regulation of the strong coupling mechanism and critical coupling conditions， the photodetection response can be enhanced by up to 160%. This work highlights the importance of optimizing dissipation and coupling parameters under strong coupling conditions， providing theoretical and design guidance for improving photoelectric conversion efficiency and enhancing the performance of quantum well infrared photodetectors.
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BU Yong-Hao, ZHOU Jing, DENG Jie, WANG Ruo-Wen, YE Tao, SHI Meng-Die, HUANG Jun-Wei, ZHANG Yu-Jie, NING Jun, LU Wei, CHEN Xiao-Shuang
2025,44(3):370-382 ,DOI: 10.11972/j.issn.1001-9014.2025.03.007
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The polarization properties of light are widely applied in imaging， communications， materials analysis， and life sciences. Various methods have been developed that can measure the polarization information of a target. However， conventional polarization detection systems are often bulky and complex， limiting their potential for broader applications. To address the challenges of miniaturization， integrated polarization detectors have been extensively explored in recent years， achieving significant advancements in performance and functionality. In this review， we focus mainly on integrated polarization detectors with innovative features， including infinitely high polarization discrimination， ultrahigh sensitivity to polarization state change， full Stokes parameters measurement， and simultaneous perception of polarization and other key properties of light. Lastly， we discuss the opportunities and challenges for the future development of integrated polarization photodetectors.
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TAN Cheng, YAN Chuan-Feng, ZANG Shan-Zhi, WANG Kai, GAN Liang-Hua, CAO Chen-Tao, CHEN Bing-Qi, CHEN Hong-Tai, ZHANG Yue-Heng, FANG Yu-Long, XU Gang-Yi
2025,44(3):383-392 ,DOI: 10.11972/j.issn.1001-9014.2025.03.008
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A single-mode terahertz quantum cascade laser （THz-QCL） with a two-dimensional patch antenna array as a resonant cavity is proposed and realized. The active region of each patch antenna is sandwiched between two metal layers， exhibiting full-scale subwavelength characteristics and exciting a vertical electric quadrupole mode with low radiation loss. The inter-antenna coupling within the array effectively suppresses electromagnetic leakage in the plane， allowing for a high-quality factor and low threshold current density even with only a few antennas in the array. As a result， the laser''s power consumption is reduced to 950 mW. Moreover， the discrete antenna array design provides a larger heat dissipation area compared to the heat-generating area， and with the lateral heat dissipation channels offered by the unpumped regions， the thermal resistance per unit area is as low as 5.6 mK/W/cm2. By significantly reducing power consumption and enhancing heat dissipation efficiency， the laser achieves a lasing frequency of 3.18 THz， a side-mode suppression ratio （SMSR） of 19.5 dB， and a beam divergence angle of 35°×35°. It operates continuously at 3.14 mW at 20 K， with a maximum continuous operation temperature of 90 K， notably higher than that of Fabry-Pérot cavity lasers made from the same material. This work provides a novel approach to improve the continuous operating temperature of THz-QCLs.
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LI Yu-Han, YANG Bao-Yu, ZHANG Qiang, GUO Zhi-Peng, WU Yi-Nong, TANG Xiao, LI Shang-Ju
2025,44(3):393-404 ,DOI: 10.11972/j.issn.1001-9014.2025.03.009
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The Infrared Hyperspectral Atmospheric Sounder II （HIRAS-II） is the key equipment on FengYun-3E （FY-3E） satellite， which can realize vertical atmospheric detection， featuring hyper spectral， high sensitivity and high precision. To ensure its accuracy of detection， it is necessary to correlate their thermal models to in-orbit data. In this work， an investigation of intelligent correlation method named Intelligent Correlation Platform for Thermal Model （ICP-TM） was established， the advanced Kriging surrogate model and efficient adaptive region optimization algorithm were introduced. After the correlation with this method for FY-3E/HIRAS-II， the results indicate that compared with the data in orbit， the error of the thermal model has decreased from 5 K to within ±1 K in cold case （10 ℃）. Then， the correlated model is validated in hot case （20 ℃）， and the correlated model exhibits good universality. This correlation precision is also much superiors to the general ones like 3 K in other similar literature. Furthermore， the process is finished in 8 days using ICP-TM， the efficiency is much better than 3 months based on manual. The results show that the proposed approach significantly enhances the accuracy and efficiency of thermal model， this contributes to the precise thermal control of subsequent infrared optical payloads.
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HUANG Song, CUI Peng-Wei, WANG Yue, WANG Liang-Liang, ZHANG Jia-Shun, MA Jun-Chi, ZHANG Chun-Xue, GUO Li-Yong, YANG Han-Ming, WU Yuan-Da, AN Jun-Ming, SONG Ze-Guo
2025,44(3):405-411 ,DOI: 10.11972/j.issn.1001-9014.2025.03.010
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A 16-channel arrayed waveguide grating （AWG） with an 800 GHz channel spacing in the O-band has been developed and fabricated based on silica planar lightwave circuit （PLC） technology. By extending the wavelength allocation from 8 channels to 16 channels as specified in IEEE 802.3bs， we increased the number of channels and boosted transmission capacity to meet the 1.6 Tbps and higher-speed signal transmission requirements for future data centers. Through optimizing the AWG structure， it has achieved insertion loss （IL） better than -1.61 dB， loss uniformity below 0.35 dB， polarization-dependent loss （PDL） below 0.35 dB， adjacent channel crosstalk under -20.05 dB， ripple less than 0.75 dB， center wavelength offset under 0.22 nm and 1 dB bandwidth exceeding 2.88 nm. The AWG has been successfully measured to transmit 53 Gbaud 4-level pulse amplitude modulation （PAM4） signal per channel and the total transmission speed can reach over 1.6 Tbps.
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ZHOU Si-Han, ZHAO Pu-Fan, HAN Qi-Jin, LUAN Chao, YANG Jian, WANG Heng, MA Yue, ZHOU Hui, LI Song
2025,44(3):412-423 ,DOI: 10.11972/j.issn.1001-9014.2025.03.011
Abstract:
The linear mode laser altimeter onboard China''s satellite is primarily used to provide elevation control points for imagery. During satellite operations， environmental variations can induce laser pointing offsets， which in turn increase the positioning errors of the footprints， thereby directly reducing the elevation accuracy of the control points. This issue is particularly pronounced in complex mountainous terrains. To enhance the reliability of laser altimeter observations from satellites in such regions， this paper proposed a new laser footprint positioning method based on waveform frequency domain matching. This method utilizes high-precision terrain data for waveform simulation and determines the position of the laser footprint by calculating the correlation between the simulated waveform and the waveform received by China''s Gaofen series satellite in the frequency domain. Additionally， systematic deviations in laser pointing are derived from the joint computational results of multi-footprint frequency domain matching. Experiments were conducted using in three regions： central Montana， western Wyoming， and eastern Utah in the United States. The results indicate that the standard deviations of footprint planar offset distances， planar true north pinch angles， and equivalent laser pointing deviation angles obtained with this method are all superior to those achieved with the time-domain waveform matching method. The findings underscore the advantages of frequency-domain waveform matching in achieving high-precision footprint localization， thereby providing a robust foundation for enhancing the utility of satellite laser altimeter observations in challenging environments and facilitating the correction of laser altimeter pointing errors.
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XU Xue-Rong, PENG Yi-Tian, GU Ming-Jian, JIANG Teng-teng
2025,44(3):424-429 ,DOI: 10.11972/j.issn.1001-9014.2025.03.012
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The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mirror translational Fourier transform interferometer （hereinafter referred to as interferometer） can be quantitatively analysed by the interferometer optical range difference velocity stability. The article proposes a more comprehensive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer kinematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection. The method incorporates the structural response of the interferometer caused by external excitation into the stability analysis as one of the influencing factors， so as to reflect the reliability of the interferometer in orbit more realistically， and judge the microvibration criticality that the interferometer can withstand more accurately. At the same time， an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism. The method discussed in the article provides a way of thinking for the judgement of the reliability of the mechanism movement under the external excitation perturbation as well as the research on the optimisation of the mechanism control.
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GE Sun-Yi, LUO Xiao-Wei, FENG Shi-Yang, WANG Bin
2025,44(3):430-443 ,DOI: 10.11972/j.issn.1001-9014.2025.03.013
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The existing deep learning-based image blind super-resolution algorithms only utilize neural networks to learn the end-to-end mapping from low-resolution （LR） images to high-resolution （HR） images， only allowing the network to implicitly learn image priors， resulting in algorithms that still produce blurry super-resolution results. To address the above issues， a deep learning image blind super-resolution algorithm guided by sparsity and self-similarity priors is proposed. Initially， for various LR image inputs， a dynamic linear kernel estimation module is employed to effectively estimate the corresponding blur kernels； Subsequently， a deep unfolding deconvolution filtering module based on the Fast Iterative Shrinkage-Thresholding Algorithm （FISTA） is utilized to explicitly model the sparsity prior of signal， achieving deconvolution restoration of the degraded images； Finally， a dual-path multi-scale large receptive field restoration module leverages the self-similarity prior of images for super-resolution recovery. The experimental results indicate that， compared to existing methods， the proposed algorithm achieves a peak signal-to-noise ratio （PSNR） of 31.66 and a structural similarity index （SSIM） of 0.8725 on the publicly available Gaussian8 dataset， and attains a PSNR of 29.08 and an SSIM of 0.8007 on the DIV2KRK dataset. The images restored by the proposed algorithm not only exhibit the highest restoration metrics but also superior visual quality.
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2025,44(3):444-450 ,DOI: 10.11972/j.issn.1001-9014.2025.03.014
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One of the key areas of advancement in space-based infrared sensing is the high-sensitivity detection of small and weak targets. A major innovation in this regard is the design of the infrared detection system indicator， which is influenced by the characteristics of the target background radiation. The effectiveness of space-based infrared detection is significantly challenged by airborne targets， especially civil aircraft. These targets are active in the upper troposphere and lower stratosphere. They exhibit weak and variable radiation characteristics due to complex background clutter and atmospheric attenuation. Aiming to address this issue， this paper proposes a multi-parameter joint optimization method for an airborne target infrared detection system based on the coupling of the multiple physical effects. Firstly， the initial optimization of the target detection spectral band in the sky is completed based on the spectral radiation characteristics of the target， the background， and the spectral atmospheric transmittance change characteristics of the target-sky-based detection platform. Subsequently， the detection sensitivity requirements are proposed. Then， a system parameter optimization method is established with the target motion speed limit， earth background limit， and detection sensitivity as the three major boundaries. This method facilitates the creation of an infrared detection index system for air targets.
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DU Shu-Hao, ZHENG Xian-Tong, JIA Han, CUI Jin-Tao, ZHANG Shi-Ya, LIU Yuan, FENG Yu-Lin, ZHANG Chun-Qian, LIU Ming, ZHANG Dong-Liang
2025,44(3):451-457 ,DOI: 10.11972/j.issn.1001-9014.2025.03.015
Abstract:
In the process of power scaling large-area Quantum Cascade Lasers （QCLs）， challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered. These issues become particularly pronounced with an increase in ridge width， resulting in multimode problems. To tackle this， an innovative multi ridge waveguide structure based on the principle of supersymmetry （SUSY） was proposed. This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side. The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design， and the optical loss of the auxiliary waveguides suppresses these modes， thereby achieving fundamental mode lasing of the wider main waveguide. This paper employs the finite difference eigenmode （FDE） method to perform detailed structural modeling and simulation optimization of the 4.6 μm wavelength quantum cascade laser， successfully achieving a single transverse mode QCL with a ridge width of 10 μm. In comparison to the traditional single-mode QCL（with a ridge width of about 5 μm）， the MRW structure has the potential to increase the gain area of the laser by 100%. This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers， which is of considerable significance.
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YE Min-Rui, CUI Wen-Nan, HUANG Xia-Yang, ZHANG Tao
2025,44(3):458-467 ,DOI: 10.11972/j.issn.1001-9014.2025.03.016
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The study aims to reveal the detection advantages of infrared polarization imaging systems deployed on aerostat platforms in sea fog conditions. Firstly， based on the polarization bidirectional reflection distribution function， this research analyzes the rule of polarization characteristics varying with observation angles， demonstrating the applicability of infrared polarization in oblique imaging from aerostats. Secondly， by using the Monte-Carlo method and minimum resolvable temperature difference （MRTD） model， the study develops a model to determine the maximum operating distance of infrared polarization imaging systems. This model verifies the superiority of infrared polarization imaging over infrared intensity imaging in terms of maintaining features and detection distance under sea fog conditions. The results provide theoretical analysis and simulation evidence supporting the deployment of infrared polarization technology on aerostat platforms.
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YUAN Di-Jian, XU Xin-Ke, LIU Tong, WANG Jin-Wen, DU Yu
2025,44(3):468-475 ,DOI: 10.11972/j.issn.1001-9014.2025.03.017
Abstract:
Target center positioning is a critical technology in the calibration process of infrared thermal images. Given the relatively complex morphology of target images， we propose a center positioning algorithm based on improved template matching with self-constructed convolution kernels. First， the algorithm constructs a normalized template with target image features and performs matching operations on subsampled and preprocessed target images to obtain coarse positioning results. Based on the coarse positioning center， the original image undergoes region of interest （ROI） fine matching， and further correction is achieved through a subpixel subdivision algorithm. Ultimately， the precise target center position is determined. This algorithm effectively detects target images with blurring and indistinct edge features， avoiding interference from blurring， occlusion， complex backgrounds， or indistinct features. It demonstrates good robustness， accurately positions the target center， and operates at high speed. Compared to traditional template matching methods like cross-correlation （CCORR）， normalized cross-correlation （NCC）， and Hough transform， it offers significant improvements and meets the positioning requirements in the automatic calibration process of infrared thermal imagers.
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Volume 44,2025 Issue 3
Infrared Physics, Materials and Devices
Millimeter Waves and Terahertz Technology
Infrared Spectroscopy and Remote Sensing Technology
Infrared Optoelectronic System and Application Technology
Interdisciplinary Research on Infrared Science
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HUANG Jin, ZHANG Li-Fu, XU Shu-Hao, SUN Xue-Jian, DUAN Yi-Shan, ZHAO Zhi-Peng, ZHAI Hao-Ran, WANG Qian
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
An overview is provided of the research progress in the application of hyperspectral detection technology for non-destructive testing of key parameters in tobacco leaf quality. Methods and equipment for the rapid detection of chemical components such as total sugar， reducing sugar， total nitrogen， nicotine， starch， chloride， and potassium in tobacco leaves using this technology are explored. The impact of different tobacco sample forms on spectral data is pointed out. The advantages and challenges of hyperspectral technology in applications such as field management， harvest optimization， and online grading in tobacco production are analyzed. The promising prospects of combining hyperspectral technology with artificial intelligence to build predictive models for tobacco leaf chemical composition are proposed. This combination provides scientific evidence and references for improving detection efficiency and quality in the tobacco industry.
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XIAO Feng, ZHANG Xiao-Qiu-Yan, CHENG Li, XU Xing-Xing, ZHANG Tian-Yu, TANG Fu, HU Tao, HU Min
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Enamel demineralization often occurs in the early stage of dental caries. Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries. Terahertz （THz） technology， especially continuous wave （CW） THz near-field scanning microscopy （THz-SNOM） with its nanoscale resolution， can be promising in biomedical imaging. In addition， compared with traditional THz time-domain spectroscopy （TDS）， portable solid-state source as the emission has higher power and SNR， lower cost， and can obtain more precise imaging. In this study， we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale. We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens， mainly due to the decrease in permittivity. This new approach offers valuable insights into the microscopic processes of enamel demineralization， laying the foundation for further research and treatment.
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ZHANG Lei, LI Xiao-Ran, CHEN Wen, LEI Liang-Xin-Wen, WU Hao, LU Zhong, DONG Bi-Qin
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Optical Coherence Tomography （OCT） provides high-resolution images of skin tissue structure and pathological features. Automated image analysis methods （such as segmentation and classification） are important for assisting skin disease diagnosis and treatment evaluation. These methods provide quantitative support for medical decisions. Compared with traditional methods and early machine learning （ML） techniques， deep learning （DL） improved analysis efficiency and reproducibility. It also reduced manual processing time significantly. This paper systematically reviewed the application progress of DL in skin OCT image analysis. It focused on technical approaches for image denoising， skin layer segmentation， and skin cancer diagnosis. The study identified key challenges including model generalization and data heterogeneity. The findings provide theoretical references and technical guidance for future research directions.
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WANG Jian-Ping, WANG Lin-Yi, DONG Bi-Qin
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
High spatiotemporal resolution multi-region brain synchronization imaging is a critical requirement in neural circuit research. However, traditional multiphoton microscopy is limited by its single field-of-view (FOV) imaging mode, making it difficult to achieve large-scale observation of neural activity across multiple brain regions. The multi-FOV multi-photon imaging technology employs a FOV segmentation strategy in both the front and rear optical paths of the objective lens and combines multi-dimensional signal analysis methods (such as wavelength encoding, spatial demultiplexing, and time gating) to effectively overcome the spatiotemporal resolution limitations of traditional techniques. This technology enables millisecond-level temporal resolution and micron-level spatial resolution for synchronous imaging across brain regions, providing a novel research paradigm for revealing cortical functional coupling, cortical-subcortical neural circuit coordination mechanisms, and whole-brain neural signal propagation dynamics. In the future, through in-depth integration with techniques such as endoscopic imaging, adaptive optical aberration correction, optical stimulation and deep learning-based image analysis, multi-FOV multi-photon imaging will further advance the precise decoding of neural circuit functional architecture and demonstrate significant value in clinical translation fields such as neurodegenerative disease diagnosis and brain-machine interface development.
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XU Shi-Wen, WU Hua-Kun, ZHOU Chong-Qiu, WU Xiao-Yu, YANG Chao-Feng, WU Qiong, LIU Wen, SHAO Jie
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The concentration of exhaled CO as a biomarker for certain diseases has attracted significant attention. However， existing CO concentration detectors suffer from low sensitivity and slow response times. To address this， we developed a high-sensitivity， rapid-response exhaled CO measurement system based on absorption spectroscopy， utilizing a quantum cascade laser with a central wavelength of 4.59 μm and a 3.8 m multi-pass cell. The CO concentration was analyzed using both direct absorption spectroscopy （DAS） and wavelength modulation spectroscopy （WMS）. The DAS method demonstrated a linearity of 0.998 with a detection limit of 3.68 × 10??. For WMS， the linearity remained 0.998 at CO concentrations below 6.00 × 10??， achieving a detection limit of 3.00 × 10??. Through Allan variance analysis， optimal integration times of 170 s for DAS and 250 s for WMS were determined， corresponding to improved detection limits of 2.00 × 10?? and 3.00 × 10?1?， respectively. Finally， exhaled CO concentrations from 14 volunteers were measured， demonstrating the system"s capability to distinguish between smokers and non-smokers. This provides a scientifically validated tool for assessing smoking status in clinical smoking cessation programs.
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ZHONG Qin-Yang, ZHANG Xiao-Qiu-Yan, WANG Ran, ZHANG Tian-Yu, TANG Fu, JIANG Pei-Du, HU Min
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Fibroblasts support a broad range of essential organ functions via microarchitectural， biomechanical， and biochemical cues. Despite great advances in fluorescence， photoacoustic conversion， and Raman scattering over the past decades， their invasiveness and limited spatial resolution hinder the characterization of fibroblasts in a single cell. Here， taking mouse embryonic fibroblasts （MEFs） as an example， we propose a novel noninvasive approach to investigate the compositional distribution of MEFs at the single-cell scale via terahertz （THz） nanoscopy. Compared to the topological morphology， THz nano-imaging enables the component-based visualization of MEFs， such as the membrane， cytoplasm， nucleus， and extracellular vesicles （EVs）. Notably， we demonstrate the real-space observation of the influence of rapamycin treatment on the increase of EVs in MEFs. Moreover， the line-cut and area-statistical analysis establishes the relationship between the topological morphology and the THz near-field amplitudes for different cellular components of MEFs. This work provides a new pathway to characterize the effects of pharmaceutical treatments， with potential applications in disease diagnosis and drug development.
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ZHANG Yi-Ze, LIU Rong, YU Yue-Wen, ZHAO Dong-Jie, CHEN Wen-Liang, LI Chen-Xi
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Near-infrared spectroscopy is a type of molecular vibration spectroscopy. Temperature variations cause changes in molecular vibrations such as O-H and inter molecular forces such as hydrogen bonding， which lead to absorption spectral intensity and peaks changes， affecting the prediction accuracy of minor components such as blood glucose. To address the impact of temperature perturbation on spectral detection and modeling analysis， a method of temperature perturbation discrimination based on aquaphotomics and two-trace two-dimensional correlation spectroscopy （2T2D-COS） was proposed. The 2T2D-COS analysis was applied to diffuse reflectance spectra of simulated solutions under temperature perturbation and varying glucose concentrations. Spectral features induced by changes in temperature and glucose concentration were successfully extracted， revealing distinct water spectral patterns under different perturbations. Quantitative analysis shows that temperature changes of 0.1 °C is equivalent to glucose concentration changes of 45 mg/dL in terms of intensity. A temperature perturbation outliers discrimination model was further established based on raw spectra， water spectral features， and 2T2D-COS asynchronous spectra. The accuracy rates of the model based on 2T2D-COS asynchronous spectra are 95.83%. After removing outliers， the root mean square error of glucose concentration prediction is reduced by 51.89%. This work provides a foundation for improving the accuracy of in vivo blood glucose detection using near-infrared spectroscopy.
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LI Hai-Bin, WANG Yu-Ye, WANG Ze-Long, XU Bing-Feng, XU De-Gang, YAO Jian-Quan
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Traumatic brain injury is one of the most serious diseases that endanger human health. Sensitive and rapid detection method is a kind of powerful guarantee for the accurate and effective treatment of traumatic brain injury. In recent years， terahertz （THz） wave and Raman spectroscopy have broad application prospects in biomedical diagnosis and other fields due to their complementarity in technology. In this article， the researches of terahertz wave and Raman spectroscopy technology in traumatic brain injury detection were summarized in response to the needs and difficulties of traumatic brain injury diagnosis. Firstly， the development status of THz imaging and THz spectroscopy technology was introduced， and the applications of the two technologies in traumatic brain injury detection were also introduced， respectively. In addition， the principle and classification of Raman spectroscopy were summarized， and the research of Raman spectroscopy in the detection of traumatic brain injury tissues， body fluids， and biomarkers were discussed. Finally， the development trend of THz wave and Raman spectroscopy in the detection of traumatic brain injury was analyzed， which provides a new research idea for the application of THz wave and Raman spectroscopy in the rapid and accurate diagnosis of traumatic brain injury.
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GUO Rui, LOU Yi, ZHANG Xin-Yuan, GUO Liang, HU Yi-Hua
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Reflective tomography lidar (RTL) reconstructs target contours by acquiring laser echo projection data, but incomplete angular detection in practice often leads to insufficient projection data. To address this issue, the authors proposes a target contour reconstruction method that combines the structural sparsity of projection data with a super-resolution convolutional neural network (SRCNN), based on the principles and technical implementation of RTL. This approach effectively resolves the failure of traditional algorithms when projection data suffers from severe angular deficiency. Different from conventional RTL imaging methods that directly incorporate sparse reconstruction models, the authors first recovers full-angle projection data by integrating sparse constraints with SRCNN based on geometry prior of the projection data, followed by standard RTL imaging algorithms to achieve complete targets contour reconstruction. To validate the effectiveness of the proposed method, the authors designed laser echo projection simulations based on the facet model and conducted field experiments. The results demonstrate that the authors achieves high-quality target contour reconstruction under varying levels of projection data missing conditions.
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LI Ze-Ying, JIA Li-Fang, ZOU Ying-Xue, GAO Feng, LIU Dong-Yuan
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Central precocious puberty （CPP） is mainly caused by the premature activation of the hypothalamic-pituitary-gonadal axis， which leads to abnormal hormone levels and triggers structural and functional changes in the brain， making the neurovascular coupling mechanisms of children with CPP different from those of normal children in the task state. Addressing current limitations of clinical diagnosis， such as false negatives， interference from obesity， and physiological discomfort， this study utilized functional near-infrared spectroscopy （fNIRS） to analyze task-related brain activation characteristics in 167 children from Tianjin Hospital， including 85 normal children and 82 children with CPP. An auxiliary diagnostic model for CPP was established based on these analyses. It was found that the prefrontal activation areas during mental arithmetic （MA） were more in the normal group than in the CPP group， and the activation areas were more in females than in males. By selecting mean， variance， kurtosis， and skewness from the two channels with the highest frequency of correlation and the highest magnitude of negative correlation as input features， the constructed classification model achieved an accuracy rate of 79.1%. This study provides a new and important reference for the rapid screening and pathogenesis study of CPP.
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ZHAO Yuan-Qiang, ZHANG Chen, ZHANG Yi-Heng, YANG Jian, WANG Kai-Xin, LI Shao-Hui, ZHOU Hui, MA Yue
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The forward scattering error in water bodies is one of the primary error sources in spaceborne laser bathymetry， with individual errors potentially exceeding the depth accuracy requirements of hydrographic surveying standards. However， traditional scattering correction methods developed based on waveform information cannot be applied to the discrete photons from photon-counting lidars. In this study， a Monte Carlo simulation is used to estimate the forward scattering errors in the water column for spaceborne photon-counting lidars and an empirical formula is derived for its rapid error correction. The quantitative analysis on this correction method demonstrates that the rapid scattering error correction is practicable and reliable using the initially corrected bathymetry data of ICESat-2 and the MODIS global water backscattering coefficient at 531 nm as inputs. Further sensitivity analysis indicates that the method performance mainly depends on the uncertainty of water backscattering coefficients. With the backscattering coefficients error constrained within 20%， the empirical formula reduces the scattering error residuals to less than 0.45% of the water depth. Under four typical water conditions， the empirical formula demonstrates an average 72% reduction in water forward scattering errors， effectively eliminating the majority of scattering-induced inaccuracies. The analysis of system parameters indicates that the derived ICESat-2 correction formula can be extended to other spaceborne photon-counting bathymetric lidars through considering the receiver field-of-view radius.
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Chen Baolin, Jin Ge, Wang Chong, Chen Lian
Abstract:
Despite rapid advancements in lidar technology， extremely long-range observation remains a significant challenge. Recently， 2μm lasers have demonstrated a potential to be applied in CDWL（Coherent Doppler Wind Lidar） system， for its high atmospheric penetration capability through the atmosphere and high potential laser power. In this study， we present a 2μm balanced detector that consists of a pair of commercial positive-intrinsic-negative （PIN） diodes with a low-noise transimpedance circuit. To meet the high bandwidth requirements， the highspeed transimpedance circuit and bias voltage tuning method were utilized to overcome the large capacitance of PIN diodes. The circuit transfer function， stability analysis and noise calculation have been studied. The detector was co-packaged with a data acquisition module for convenient data transmission and bias voltage control. The characteristics of the detector， including bandwidth， noise and bias voltage influence， are evaluated in laboratory. Results show that the RMS value of the balanced detector background noise is 539 μV and the bandwidths of the two diodes are 110.8 MHz and 110.3 MHz， respectively. The evaluation results show that the balanced detector meets the wind measurement requirements and allows for a 1.45× increase in bandwidth through bias voltage tuning. Our work offers insights into lidar detector design and bandwidth enhancement， providing a valuable reference for researchers and professionals in the field. More importantly， it lays a critical foundation for future ultra-long-range and space-borne 2μm coherent wind lidar systems by addressing key device-level challenges.
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LEI Zi-ang, YANG Song, SHEN Zheng-Ming, LI Tong, WANG Zi-Hao, ZHANG Rui-Zhe, ZHANG Jing-Hao, ZHENG Yong-Chao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The diffuse attenuation coefficient （Kd） is a crucial parameter in ocean optics， representing an apparent optical property influenced by the inherent optical characteristics of seawater and the surrounding light field. It is closely related to factors such as seawater quality and chlorophyll concentration. As an active remote sensing instrument， marine polarized lidar emits light in the blue-green wavelength band capable of penetrating seawater， offering all-weather detection potential， and possesses a distinct edge in mapping the vertical distribution of Kd within the ocean. By combining Fernald"s backward iteration and slope approaches， this study proposed a layered inversion method for oceanic profile Kd estimation， utilizing dual-polarization channel signals. The vertical polarization channel is specifically used to suppress surface signals and enhance near-shore oceanic backscatter. Conducted in the Yellow and East China Seas， the ocean lidar was mounted on a marine experimental platform， with a 10-meter water depth used to validate the stratification algorithm. Results show a polarization degree of 0.479 at the sea surface for the dual-polarization channel signal. With a vertical resolution of 1 meter， the stratified inversion of the oceanic profile Kd using dual-polarization channels yields a root mean square error of 0.049 compared to actual in-situ measurements， representing a 52.4% improvement in accuracy over non-polarized channel signals. Additionally， the layered inversion algorithm outperforms the traditional Fernald algorithm， demonstrating a 32.4% improvement in precision.
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HU Jian-Bo, WANG Xiong, MA Peng-Fei, ZHAO Shao-Hua, YANG Ju-Xin, DAI Guang-Yao, XIE Yuan, ZHU Xiao-Peng, LIU Dong, HOU Xia, BU Ling-Bing, LIU Ji-Qiao, CHEN Wei-Biao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In April 2022， the Atmospheric Environment Monitoring Satellite （DQ-1） was launched with its main payload Aerosol and Carbon Detection Lidar （ACDL）. The ACDL is the first spaceborne high-spectral-resolution aerosol detection lidar with great performance in aerosol profile measurement. The accuracy of ACDL was quantified （R2 = 0.924） by comparing the aerosol optical depth （AOD） between ACDL and Aerosol Robotic Network （AERONET）. In March 2025， frequent dust events occurred in northern China， generating substantial quantities of dust aerosols. The spatiotemporal distribution characteristics and optical properties of dust aerosols were analyzed. The results indicated that aerosols were mainly concentrated in troposphere， with the depolarization ratio of 0.19–0.38 and the lidar ratio of 38–60 sr， exhibiting typical optical characteristics of dust. The vertical distribution demonstrates a maximum dust aerosol layer height reaching 5 km， while spatially extending over 1600 km in horizontal dimension. This study confirms the observational advantages of high-spectral-resolution detection technique from ACDL in complex aerosol environments， providing important data for atmosphere pollution research.
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WANG Zhang-Jun, ZHUANG Quan-Feng, LI Hui, LI Hao, LIU Dong, CHEN Chao, PAN Xin, CHEN Shuo, LI Chuan-Dong, XUE Bo-Yang, XU Zhi-Jun
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Aerosol and wind field are important parameters for studying the marine atmosphere， and it is of great significance to achieve high-precision measurements. In order to realize high-temporal and spatial resolution airborne observation of atmospheric aerosols and wind fields at sea， the ship-borne atmospheric multi-parameter detection lidar has been developed. The structural design， detection principle， technical indicators and retrieval method of ship-borne atmospheric multi-parameter detection lidar are introduced. Through experimental calibration tests， the system was calibrated for atmospheric molecular Rayleigh tests and wind field observation calibration tests， which verified the observation characteristics and accuracy of the system. The experimental data of low-altitude atmospheric multi-parameter walking observation at sea carried out in the Yellow Sea and East China Sea of China on board the "Luqing Yujiao 16" test vessel in August 2024 were analyzed， and aerosol optical parameters of 0-10 km and wind field information of 0-5 km during the walking observation period were obtained. The data results show that the aerosol concentration at sea changes significantly， and there are low-level aerosol layers and low-level clouds. The atmospheric wind speed at low-level sea is basically below 20 m/s； the boundary layer height distribution fluctuates around 1 km； taking altitudes of 200 m， 500 m and 1000 m as examples， the differences in aerosol， wind speed and wind direction distribution at different altitudes on the sea are analyzed. Experimental results show that atmospheric multi-parameter detection lidar can be equipped with ocean platforms such as ships and buoys to efficiently achieve continuous and accurate observations of aerosol and wind fields over the ocean.
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ZHANG Qing-Fan, XIE Huan, Yan Xiong-Feng, JIN Yan-Min, CHEN Jie, XI Yuan-Ting, XIE Jun, MA Yue-Chao, ZHU Fei-Hu, TONG Xiao-Hua
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A hybrid solid-state LiDAR system specifically designed for detecting rapidly rotating small celestial bodies was introduced. The ranging principle was analyzed and an imaging model was designed based on the characteristics of the fast steering mirrors and the single photon array detector. To evaluate the performance and stability of the LiDAR system in small celestial body detection， a mapping validation method based on an outdoor sandbox featuring small celestial bodies was proposed. The results show that the hybrid solid-state LiDAR system maintains high accuracy under different operating modes and power levels. In the global terrain mapping mode， the resolution is 1100×1100， and the imaging time is 0.86 s. The mapping accuracy is 2.86 cm at a distance of 100 m. In the step-scanning imaging mode， the resolution is approximately one-seventh that of the global terrain mapping mode， and the average accuracy reach 3.10 cm at distances between 34 and 83 m.
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GUO Jin-Quan, LI Guo-Yuan, PANG Xiao-Ping, SHEN Dong-Liang, DING Bao-Shuai
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Polar regions play a crucial role in the global climate system， serving as indicators and amplifiers of climate change. Their unique geographical environment and climate processes have a significant impact on the Earth system. Laser altimetry technology， with its sub-meter or even centimeter-level measurement accuracy， has received much attention in polar research. In recent years， the number of satellites carrying laser altimetry payloads in China has gradually increased. However， there are few polar studies based on the altimetry data from Chinese satellites. This paper first verifies the polar elevation accuracy of domestic satellite laser altimetry data using reference terrain. The results demonstrate that the laser data from GF-7 and ZY-3 03 satellites achieve accuracies better than 1 meter in polar regions， while the Terrestrial Carbon Monitoring Satellite exhibits an accuracy of approximately 1.2 meters. Subsequently， laser altimetry data is employed to assist in constructing three-dimensional polar terrain from stereo imagery， with the resulting topographic products meeting the cartographic standards for 1：10，000 scale topographic maps， thereby validating the effectiveness of the composite surveying and mapping method in polar regions. Finally， multi-source laser altimetry data is integrated to calculate ice sheet surface elevation changes， revealing the application potential of domestic satellites in polar change monitoring. This study comprehensively evaluates the polar application capabilities of domestic satellite laser altimetry data from multiple perspectives， providing critical references for future large-scale polar research utilizing domestic satellite data.
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LI Jia-Yi, ZHANG Pei-Jin, XIA Qi-Ming, QIAN Jun
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
NIR-II fluorescence imaging demonstrates significant advantages in biological imaging with its high signal-to-background ratio （SBR） and deep tissue penetration， showing broad application prospects in biomedical fields. The classification of NIR-II imaging windowsfacilitates the optimization of imaging processes. Among these， the 1400-1500 nm imaging window benefits from its unique water absorption characteristics， enabling effective suppression of scattering background and achieving high-contrast imaging. This study systematically evaluates the imaging potential of the 1400-1500 nm window through simulation studies and in vivo experiments. To advance the clinical translation of fluorescence imaging in the 1400-1500 nm window， indocyanine green （ICG）， an organic small-molecule dye approved by the U.S. Food and Drug Administration （FDA）， was employed as the fluorescent probe. Utilizing its extended fluorescence emission tail in the NIR-II region， high-contrast and high-resolution imaging of mouse vasculature and intestinal structures was achieved in the 1400-1500 nm window. Furthermore， in combination with methylene blue （MB）， another FDA-approved agent， high-quality dual-channel NIR-II imaging was successfully implemented enabling precise localization of blood vessels and lymph nodes in mice. This research further explores the unique advantages of the 1400-1500 nm imaging window in biological imaging and its clinical application potential. It also provides valuable references for the clinical translation of NIR-II fluorescence imaging.
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Zhao Sisi, Zhang Jinghao, Li Tong, Zheng Guoxian, Zheng Yongchao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Optical detection of space target is the premise for debris collision avoidance， early warning and active removal， which is considered as the basis to safety protection of spacecraft and sustainable development of outer space activities. And lidar can achieve all-day detection and is an important supplement to passive optical payloads. This paper used detection system based on single photon detector， which had the time and position record function for the arrival signal， to measure the time-position three-dimension information of the target crossing the field-of-view of the detection system. And the twice Hough transforms were applied to determine the trajectory of the target at low SNR. The experiment results showed that the moved targets could be detected at the condition of SNR<2， and the trajectory could be determined accurately under the condition of bright background and target. This work hopes to provide reference for high sensitive detection of the dim fast target.
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SHEN Zhen-Min, ZHENG Yong-Chao, SHANG Wei-Dong, YANG-Song, ZHANG Jing-Hao, SUN Qian, LEI Zi-Ang, LIU Hui
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Based on the flight test echo data obtained by self-developed airborne dual-frequency ocean profile LiDAR， the bathymetric error caused by wave refraction and water scattering was analyzed， and the correction method was proposed based on the combination of Genetic Algorithm （GA） and Levenberg-Marquarelt （LM） algorithm. Theoretical analysis shows that compared with the signal LM algorithm， this wave refraction correction method reduces the Root Mean Square Error （RMSE） of the inversion of sea wave profile by about 50%. The inversion method of water body optical parameters based on the seawater profile backscattering part of the measured echo signal was researched ， and the errors and influencing factors introduced in the inversion of water optical parameters based on the Fernald backward iterative integration method were theoretically analyzed， it is found that when the estimated value of the “particle laser radar ratio” deviates by a% from the true value compared to –a%， the errors in the inversion of water body diffuse attenuation coefficient and 180° volume scattering coefficient are smaller.
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LIANG Zhuan-Xin, LAI Xu-Dong, CHEN Dong-Wu, Yan Yi-Tian
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Semantic segmentation of airborne point clouds provides essential data support for downstream applications. Fully supervised deep learning methods typically rely on large amounts of annotated data， while some weakly supervised approaches struggle to learn representative features effectively due to the randomness in label selection. To address these challenges， a label-efficient semantic segmentation method is proposed， which integrates an active learning strategy to progressively update the training set by actively selecting the most informative points based on information entropy in each learning cycle. Experimental results on the LASDU and H3D datasets show that， with only 0.5% and 0.1% labeled data， the proposed method outperforms existing approaches in segmentation accuracy， demonstrating its efficiency in weakly supervised conditions.
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Chen Jie, Li Guo-Yuan, Cui Xi-Ming, Yan Deng-Hua, Shen Dong-Liang, Zhang Bin, Liu Chang-Ru, Zhou Xiao-Qing, Yuan De-Bao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The GF-7 satellite is equipped with China "s first operational earth observation laser altimeter and sub-meter optical stereo camera. High-precision laser altimetry data and sub-meter-level optical imagery data enable 1：10，000-scale stereoscopic mapping without ground control points， offering unique application advantages in large-scale spatial infrastructure construction for digital twin water resources management and water level monitoring of lakes and reservoirs. In the study， Miyun Reservoir is taken as the main research area. The GF-7 laser altimetry data and stereo image are used to extract the reservoir water level and the surrounding digital surface model（DSM）， and the application practice analysis is carried out. The results show that the absolute error of reservoir water level extracted based on laser altimetry data is less than 0.15 m， which is equivalent to the accuracy of the same type of foreign data. Based on the digital surface model， the water surface range prediction result F1 is higher than 0.85， and the water volume change monitoring error is less than 3%， which can meet the requirements of related hydrological analysis applications. The relevant conclusions are of reference value for promoting the application of domestic GF-7 satellite laser altimetry and stereo image data in water conservancy， and better assisting the construction of basin level digital twin water conservancy.
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XIN Wen-Hui, HE Yi-Xin, YAO Jie, LI Shi-Chun, GUO Yan, GAO Shan, DI Hui-Ge, HUA Deng-Xin
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In order to monitor forest fires， a high-repetition-rate polarization lidar system was developed based on the light scattering and polarization effects of smoke particles generated during fires. The system consists of subsystems for laser emission， optical reception， Echo signal acquisition and processing， and scanning control. To meet the requirements of large-scale， high-resolution， and time-sensitive forest fire detection， a high-power， high-repetition-rate laser was selected as the detection source， combined with a high-angular-resolution gimbal to enable precise scanning. At a lidar repetition frequency of 5 kHz， the system can perform patrol scanning of a forest area with a 10 km radius in 48 minutes with an angular resolution of 1°. To address the challenges of echo signal acquisition and cumulative averaging during high-repetition-rate detection， a novel and dedicated “readout-accumulation-storage” IP （Intellectual Property） architecture was designed， efficiently achieving echo signal acquisition and improving the signal-to-noise ratio. The completed high-repetition-rate polarization lidar underwent near- and far-field simulation experiments， with detected peak points aligning with fire locations. Deployed in Yan’an City， the lidar successfully detected simulated fires at distances of 5.4 km and 8.1 km， validating the system’s effective detection capability.
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HUANG Jia-Peng, FAN Qing-Nan, ZHANG Yue
Abstract:
Accurate estimation of understory terrain has significant scientific importance for maintaining ecosystem balance and biodiversity conservation. Addressing the issue of inadequate representation of spatial heterogeneity when traditional forest topographic inversion methods consider the entire forest as the inversion unit， this study proposes a differentiated modeling approach for forest types based on refined land cover classification. Taking Puerto Rico and Maryland as study areas， a multi-dimensional feature system is constructed by integrating multi-source remote sensing data： ICESat-2 spaceborne lidar is used to obtain benchmark values for understory terrain， topographic factors such as slope and aspect are extracted based on SRTM data， and vegetation cover characteristics are analyzed using Landsat-8 multispectral imagery. Innovatively， this study incorporates forest type as a classification modeling condition and applies the Random Forest algorithm to build differentiated topographic inversion models. Experimental results indicate that， compared to traditional whole-area modeling methods （RMSE=5.06 m）， forest type-based classification modeling significantly improves the accuracy of understory terrain estimation （RMSE=2.94 m）， validating the effectiveness of spatial heterogeneity modeling. Further sensitivity analysis reveals that canopy structure parameters （with RMSE variation reaching 4.11 m） exert a stronger regulatory effect on estimation accuracy compared to forest cover， providing important theoretical support for optimizing remote sensing models of forest topography.
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ZHOU Wen-Xin, ZHOU Si-Han, HAN Qi-Jin, Luan Chao, WANG Heng, ZHAO Pu-Fan, LI Song
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Satellite laser altimetry technology enables the acquisition of accurate three-dimensional coordinates of ground targets， serving as a high-precision method for Earth observation. Laser altimetry data have been widely applied in areas such as terrain mapping， polar region monitoring， and forestry surveys. The terrain profile matching method based on natural surfaces aligns the measured terrain profiles from laser altimeters with reference terrain data to determine the positioning errors of laser altimetry measurements. This approach is currently one of the most commonly used methods for the on-orbit geometric calibration and accuracy validation of laser altimeters. However， the effectiveness of terrain matching is influenced by various factors， including surface topography， the along-track length of laser data， and the spacing of laser footprints. Related research is still in its early stages. This paper focuses on two key factors affecting terrain matching： the along-track length of the laser data and the spacing of laser footprints. Using the ICESat-2 satellite， which provides the highest observation density among current missions， we extracted and downsampled its measurement data to construct a series of laser altimetry datasets. Extensive experiments were conducted over regions in North America. Based on statistical analysis of the experimental results， this study quantifies the relationship between terrain matching uncertainty， laser data track length， and footprint spacing.
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LU Qing-Kai, YAO Jia-Qi, LI Guo-Yuan, MA Chen, LIU Zhao, XIA Hao-Bin, XU Hao-Jun, WU Jian-Jun
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The Terrestrial Ecosystem Carbon Inventory Satellite （TECIS/CM-1） utilizes a combination of multi-beam lidar， multi-spectral cameras， and other passive and active sensors for synergistic observations， enabling high-resolution， comprehensive， and three-dimensional atmospheric monitoring of clouds and aerosols. In recent years， traditional algorithms have faced challenges in terms of vertical layer retrieval accuracy and robustness in complex environments with low signal-to-noise ratios， near-surface observations， and mixed multi-layer structures. To address these issues， this paper proposes TECIS-CASNet， a generalized framework for atmospheric layer recognition and application， designed for the novel multi-beam lidar on the TECIS satellite， leveraging the characteristics of the lidar data and deep learning attention mechanisms. To validate the reliability of this framework， the research team conducted multiple ground-based synchronous observation experiments to systematically evaluate its recognition accuracy. Finally， as a demonstrative application， the study focuses on a typical long-distance dust transport event in the Beijing-Tianjin-Hebei region of China， showcasing the practical application value of the framework. The results indicate that the TECIS-CASNet framework achieves high cloud-aerosol recognition accuracy， reaching 98.41%， and is capable of reducing misidentification and missed detection in complex environments， including low signal-to-noise ratios， near-surface layers， and multi-layer mixed structures. The absolute accuracy of aerosol optical depth retrieval is 0.01， with an overall accuracy of 98%. This paper， centered around the TECIS-CASNet framework， provides significant insights for lidar satellite atmospheric remote sensing data processing and environmental monitoring applications.
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ZHOU Zhi-Biao, YANG Jian, SONG Yue, LUAN Chao, YANG Zhe, LI Song
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In September 2018， NASA launched ICESat-2 （Ice， Cloud， and Land Elevation Satellite -2） which carried the unique spaceborne photon-counting lidar system ATLAS （Advanced Topographic Laser Altimeter System） in orbit so far. The lidar has the characteristics of multi beams， high repetition rate and high ranging accuracy， and has great potential in obtaining high-precision and high-resolution wave parameters. In this paper， an optimized algorithm based on point density with adaptive thresholds is proposed to extract sea surface signal photons， and a method based on sea surface geometry shape to calculate the significant wave height value of sea wave， which proves that the significant wave height value that is consistent with the NASA marine product’s can be obtained by using photon data with a length of 1 km， better than the NASA’s 3-7 km wave height data resolution. Significant wave height data is used to generate a wave height space distribution with 0.2°×0.2°grids in the South China Sea， and analyzes the spatial distribution characteristics of significant wave height and the law of its variation with time. It shows that the significant wave height values of the sea area around the Zhongsha Islands and the Luzon Strait are larger throughout the year， while the values of the Beibu Gulf， the Natuna Islands， the Sulu Sea and the Celebes Sea are smaller. The changes of wave height and wind speed with time in the South China Sea are highly synchronous， indicating that the wave in this area is mainly driven by wind. The quantitative relationships between the significant wave height and wind speed in nearshore shallow water and offshore deep water are given respectively in combination with the wind speed data of ERA5， and proves that the significant wave height of the deep water is greater than the shallow water under the same wind speed. With the help of ICESat-2 photon-counting lidar， higher resolution wave height space distribution can be obtained， especially accurate wave heights in nearshore shallow water area， which can fill the space and time gaps of other observation methods of wave， that is helpful to the optimization of wave numerical model and the oceanographic research.
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Wang Yu-Xuan, Sun Xiao-Bing, Ti Ru-Fang, Hong Lian-Huang, Yu Hai-Xiao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The vertical distribution of aerosols plays a critical role in improving the accuracy of aerosol retrieval in satellite remote sensing due to its complexity and spatiotemporal variability. This study investigated the vertical characteristics of aerosols using unsupervised clustering methods, based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Level 3 aerosol profile data from 2010 to 2020. Three clustering algorithms—Gaussian Mixture Model (GMM), K-means, and spectral clustering—were evaluated using multiple performance metrics. The profiles of extinction coefficient were clustered into five representative types using the GMM algorithm: low-pollution composite type, high-pollution composite type, exponential decay type, low-pollution uniform type, and high-pollution oscillatory type. The seasonal and regional distributions of these profile types were further analyzed over the Tibetan Plateau, the Beijing-Tianjin-Hebei region, and the Yangtze River Delta. The results show that aerosol vertical profiles exhibit distinct seasonal and regional patterns. These findings provide a basis for improving aerosol profile parameterization and retrieval accuracy in remote sensing applications.
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RAO Zhi-Min, LI Yi-Cheng, LI Yi-Xiu, Liu Jia-Xin, GONG Xin, ZHAO Hu, MAO Jian-Dong
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Bioaerosol particles are widely spread in the air， and high concentrations of bioaerosols are extremely hazardous to human health. In order to realize the early warning prediction of atmospheric bioaerosol concentration， this paper takes fluorescence lidar as the detection tool， and on the basis of obtaining the bioaerosol concentration contour， combines the relevant parameters of the atmospheric environment， optimizes the support vector machine （SVM） by using the particle swarm （PSO） and the genetic algorithm （GA） and establishes a prediction model for the bioaerosol concentration contour， by adopting the temperature， humidity， PM2.5， PM10， CO2， SO2， NO2， O3， wind speed and other related parameters as inputs and bioaerosol concentration contour data as outputs for training， determining the parameter configuration of the prediction model， and reintroducing new atmospheric parameters， predicting the bioaerosol concentration contours by using the trained model and comparing it with that detected by fluorescence lidar， and analyzing the results of the bioaerosol concentration contours predicted by the optimized model with different algorithms. The bioaerosol concentrations predicted by the optimized model and their relative errors are also analyzed.
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FANG Qiang, WANG Hong, HE Guanghui, ZHOU Zhengyu, CAO Fengwei, SONG Qinghe
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Spaceborne full-waveform lidar， as an advanced remote sensing technology， has been widely applied in various fields due to its ability to record detailed terrain and vegetation information. However， the data from spaceborne full-waveform lidar can be affected by factors such as dark current， photodetector performance， the surrounding environment of the target being detected， and background light during the acquisition process. These factors introduce significant noise into the original waveform signals， interfering with the extraction of effective echo information for target inversion analysis. To address the common problem of waveform amplitude reduction in existing classical filtering algorithms， this paper proposes an adaptive filtering compensation method for waveform amplitude. By utilizing the bat algorithm to optimize Gaussian sharpening operator parameters and convolving the Gaussian sharpening operator with the filtered waveform data， waveform compensation is achieved through adaptive iteration to ensure optimal compensation effects. This paper conducts experimental verification on GEDI （Global Ecosystem Dynamics Investigation） echo data， comparing the proposed method with various filtering algorithms. After filtering， the highest peak amplitude was reduced by an average of 9.0077 count， while the difference between the highest peaks of the waveform after Gaussian sharpening compensation and the original waveform was only 0.0182 count on average. Moreover， the average signal-to-noise ratio improved from 30.0235dB to 33.2609dB， representing a relative increase of 10.78%. The results indicate that this method， in conjunction with filtering methods， can remove noise while retaining more of the original waveform feature information. This provides more accurate data for further extraction of waveform information for geophysical parameter inversion and target classification and is applicable to a variety of filtering methods.
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Cross-source point cloud registration using an improved spherical voxel-based local shape descriptor
Li Jian, Li Huan-tao, Wu Hao, Cui Hao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
To address the registration challenges caused by cross-source point cloud quality disparities, this paper proposes an improved spherical voxel local shape descriptor (Spherical Voxel Center Descriptor, SVCD) for cross-source point cloud registration. SVCD effectively mitigates density and distribution variations through dual-weighted Local Reference Frame (LRF) computation and spherical voxel segmentation. Its core innovation lies in feature encoding based on the distance from voxel centers to keypoints, enhancing the distinctiveness and robustness of the descriptor. The registration process establishes correspondences via nearest neighbor similarity ratio and solves the rigid transformation using singular value decomposition. Experimental results on the 3DCSR and real-world datasets demonstrate that SVCD achieves a registration error as low as 0.0048, with recall rates of 82.83% and 83.45% (improving baseline performance by 10.24 and 11.16 percentage points, respectively), and the highest F1-scores (0.803 and 0.832). In Gaussian noise experiments, SVCD maintains an average recall rate of 76.54%, significantly outperforming comparative methods, validating its strong robustness in complex scenarios. This method provides an effective solution for high-precision cross-source point cloud registration.
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WANG Jun-Tao, WANG Sheng-Feng, PENG Yan
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
As a valuable Chinese herbal medicine， Panax notoginseng exhibits therapeutic efficacy and quality closely associated with its saponin content， which demonstrates significant geographical variations. To accurately authenticate the geographical origin and ensure medicinal quality， a novel method integrating terahertz precision spectroscopy with a convolutional neural network （CNN） algorithm was proposed. 40 Panax notoginseng samples from 4 regions in Yunnan Province， China—Honghe Autonomous Prefecture， Kunming， Qujing， and Wenshan Autonomous Prefecture—were analyzed using terahertz spectroscopy and high-performance liquid chromatography （HPLC）. A CNN model was constructed and trained based on the acquired spectral and chromatographic data to classify the geographical origins. Experimental results revealed that the terahertz spectroscopy combined with the CNN model achieved a classification accuracy of 92.5%， significantly outperforming the 82.5% accuracy attained by the HPLC-CNN model. This finding highlights the potential of terahertz spectroscopy in component analysis and geographical traceability of herbal medicines， providing a novel scientific approach for rapid， non-destructive， and precise identification of Chinese medicinal materials.
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ZHANG Jin-Jing, LIU Bing-Wei, LI Jia-Wei, WU Xu, SUN Li-Ying
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
This study used a terahertz metamaterial sensor for the rapid and accurate detection of the antithrombotic drug Plavix， addressing the increasing demands for efficiency and sensitivity in drug content monitoring. Utilizing the terahertz vibration characteristics of Plavix， characteristic absorption peaks within the 1-3 THz band were identified. Based on these findings， a dual-polarization resonance metamaterial sensor was designed to simultaneously enhance the sensing signals of these characteristic absorption peaks. Experimental results indicate that the sensor attains a high level of fit （R2>0.97） for quantitative analysis in the quantitative detection of Plavix through the established two-indicator decision model. Consequently， the terahertz metamaterial sensing technology presented in this study exhibits superior performance in monitoring Plavix content and offers a new tool for clinical drug monitoring and broader biochemical sample analysis.
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LI Jia-Ying, HU Dong-Sheng, ZHUANG Hao, LI Yi-Ze, JI Min-Biao
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Coherent Raman scattering microscopy is widely regarded as a powerful tool for solving biomedical problems due to its chemical specificity， label-free imaging capability， high spectral resolution and high sensitivity. However， the clinical application of coherent Raman scattering imaging technology has long been hindered by environmental sensitivity and large volume solid-state lasers. Ultrafast fiber lasers， with their compactness and stability， can effectively overcome these shortcomings. In this paper， different realization methods and research progress of fiber-based laser sources in coherent Raman scattering imaging are reviewed， including supercontinuum fiber source， soliton self-frequency shift fiber source， fiber optical parametric oscillator and synchronized fiber source， and the future development is prospected.
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LIU Jun, MAN Zhi-Hao, LI Jing-Cheng, YANG Kang-Wen
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Coherent Raman spectroscopy and imaging technology， as a new type of label-free detection technology， has been widely used in biomedicine， material science， and other fields owing to its high specificity and noninvasive advantages. In recent years， the combination of time stretching and coherent Raman spectroscopy has effectively overcome the limitations of traditional spectrometers in terms of sampling rate and spectral range and provides a new idea for high-speed and broadband Raman spectroscopy and imaging. This paper first describes the basic principle of time stretching and its theory， summarizes the results of the application of this technology in other fields， and then systematically combs through the research progress of coherent Raman spectroscopy based on time stretching. Finally， it looks forward to the future development of coherent Raman spectroscopy based on time-stretching.
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OGURA Shingo, SHAO Ke-Meng, Zhang Xiao, Li Hui-Zhu, Feng Si-Jia, WANG Yue-Ming, CHEN Jun, WU De-Hua, WO Yan
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Ischemia is a significant factor affecting the repair of peripheral nerve injuries， while exosomes have been shown to promote angiogenesis. To further investigate the detailed processes and efficacy of exosome therapy for ischemic peripheral nerve injuries， this study utilized glucose-modified near-infrared-II （NIR-II） quantum dots （QDs） to label adipose-derived stem cell exosomes （QDs-ADSC-Exos）， enabling long-term in vivo NIR-II imaging of exosome treatment for ischemic peripheral nerve damage. Experimental results confirmed that QDs can be used for non-invasive in vitro labeling of exosomes， with QDs-ADSC-Exos exhibiting strong fluorescence signals in the NIR-II window and demonstrating favorable NIR-II imaging characteristics in vivo. Notably， QDs-ADSC-Exos showed accumulation at the site of nerve injury in cases of ischemic peripheral nerve damage. Functional neurological assessments indicated that QDs-ADSC-Exos effectively promoted neural regeneration. This study highlights the potential of exosomes in treating ischemic peripheral nerve injuries and elucidates the spatiotemporal characteristics of exosome therapy， providing objective evidence for the further optimization of exosome-based treatment protocols.
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ZHANG Yu-Huang, LIU Xiao-Long, SUN Si-Ying, FAN Xiao-Xiao, LIN Hui, QIAN Jun
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Fluorescence imaging in the second near-infrared window （NIR-II， 900-1880 nm） offers high signal-to-background ratio （SBR）， enhanced definition， and superior tissue penetration， making it ideal for real-time surgical navigation. However， with single-channel imaging， surgeons must frequently switch between the surgical field and the NIR-II images on the monitor. To address this， a coaxial dual-channel imaging system that combines visible light and 1100 nm longpass （1100LP） fluorescence was developed. The system features a customized coaxial dual-channel lens with optimized distortion， achieving precise alignment with an error of less than ±0.15 mm. Additionally， the shared focusing mechanism simplifies operation. Using FDA-approved indocyanine green （ICG）， the system was successfully applied in dual-channel guided rat lymph node excision， and blood supply assessment of reconstructed human flap. This approach enhances surgical precision， improves operational efficiency， and provides a valuable reference for further clinical translation of NIR-II fluorescence imaging.
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LI Xi-Cai, ZHU Jia-He, DONG Peng-Xiang, WANG Yuan-Qing
,DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
This paper presents a high-speed and robust dual-band infrared thermal camera based on an ARM CPU. The system consists of a low-resolution long-wavelength infrared detector, a digital temperature and humidity sensor, and a CMOS sensor. In view of the significant contrast between face and background in thermal infrared images, this paper explores a suitable accuracy-latency tradeoff for thermal face detection and proposes a tiny, lightweight detector named YOLO-Fastest-IR. Four YOLO-Fastest-IR models (IR0 to IR3) with different scales are designed based on YOLO-Fastest. To train and evaluate these lightweight models, a multi-user low-resolution thermal face database (RGBT-MLTF) was collected, and the four networks were trained. Experiments demonstrate that the lightweight convolutional neural network performs well in thermal infrared face detection tasks. The proposed algorithm outperforms existing face detection methods in both positioning accuracy and speed, making it more suitable for deployment on mobile platforms or embedded devices. After obtaining the region of interest (ROI) in the infrared (IR) image, the RGB camera is guided by the thermal infrared face detection results to achieve fine positioning of the RGB face. Experimental results show that YOLO-Fastest-IR achieves a frame rate of 92.9 FPS on a Raspberry Pi 4B and successfully detects 97.4% of faces in the RGBT-MLTF test set. Ultimately, an infrared temperature measurement system with low cost, strong robustness, and high real-time performance was realized, achieving a temperature measurement accuracy of 0.3°C.
光学生物医学融合与成像技术的应用
激光雷达创新与应用
光学生物医学融合与成像技术的应用
激光雷达创新与应用
光学生物医学融合与成像技术的应用
激光雷达创新与应用
光学生物医学融合与成像技术的应用
Application of Optical-Biomedical Fusion and Imaging Technology
光学生物医学融合与成像技术的应用
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Simulation of thin-film coplanar waveguides for terahertz resonators
HU Yu-Hao, GENG Wei, SHI Sheng-Cai
Abstract:
A terahertz(THz) spectrometer plays a essential role in THz astronomy. Coplanar waveguides(CPW) are critical components in such THz spectrometers and relative permittivity is one of the most important parameters of a dielectric material. It decides the resonant frequency and the quality factor of the device. Since accurate electromagnetic field solutions of a CPW is hard to get due to its complex structure, the conformal mapping technique(CMT) is widely used to get approximative analytical expressions for effective permittivity . However it makes difference when a thin-film dielectric is involved. In this paper, we utilized High Frequency Structural Simulator(HFSS) to get effective permittivity of CPW based on resonator structure and compared it with that from conformal mapping technique. Provide possibility to characterize the thin-film dielectric through simulation.
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Dynamic terahertz wave manipulation based on dielectric metasurfaces
LI Zheng-Kun, ZHOU Hao-Yang, WANG Shun-Jia, HE Qiong, TAO Zhen-Sheng
Abstract:
We demonstrate successful terahertz (THz) wave manipulation using dielectric metasurfaces. By employing optical pumping at different wavelengths, the metasurface modulates THz waves in either mode-selective or non-selective manners. Distinct transmission relaxation processes are observed when varying the excitation photon energy, reflecting the band characteristics of silicon. Furthermore, we reveal an alternative optical control strategy through active adjustment of the pump-probe delay stage, enabling continuous tuning of THz polarization states via metasurface functionality control. We also offer according physical explanations. Our study proves that optical pumping serves as an effective external approach for dynamic THz wave manipulation, facilitating the development of versatile metasurface-based devices.
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A whispering gallery mode microsphere resonator coupled by anti-resonant reflecting guidance mechanism
Wu Jieya, WANG DONGNING, Zhao Chunliu
Abstract:
A whispering gallery mode microsphere resonator is proposed and demonstrated. The device is fabricated by splicing a single-mode fiber with a capillary tube and, by properly adjusting the discharging current and the splicing position of the fiber and capillary tube, an expanded hollow sphere cavity is formed at the splicing junction. A microsphere is inserted into the hollow sphere cavity and positioned in close touch with the cavity wall to excite whispering gallery mode resonance via the coupling of evanescent field of the anti-resonant reflecting guidance mode produced in the cavity wall. The device has a quality factor of 3.725 ′ 103 and is compact, simple in fabrication, easy in packaging, convenient in operation and of low cost.
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Research on laser self-mixing interference characterization technology of terahertz blazed grating
ZHAO Ya-Nan, WAN Wen-Jian, SHAO Di-Xiang, J. C. CAO, HAN Ying-Jun
Abstract:
This study presents the design, fabrication, characterization, and testing methodology of a reflective blazed grating operating in Littrow configuration. The grating, fabricated via mechanical ruling technology with a sawtooth profile, was characterized using a terahertz quantum cascade laser combined with self-mixing interferometry. Non-contact measurements yielded a grating constant of 84.89 μm and a blazed angle of 24.9°, with performance metrics including an angular resolution of 0.117 rad/THz and a peak diffraction efficiency of 71% within the terahertz band, consistent with theoretical predictions. By directly resolving grating parameters through laser feedback signals, this method significantly improved measurement speed compared to conventional approaches, demonstrating potential for real-time dynamic characterization of grating devices.
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Temperature-Dependent Mechanism of Ge-Based p-i-n Blocked Impurity Band Long-Wavelength Infrared Detectors
CHEN Tian-Ye, LIU Chi-Xian, WANG Ze-Xin, HU Qing-Zhi, PAN Chang-Yi, DOU Wei, LING Jing-Wei, LIU Xiao-Yan, ZHU Jia-qi, DENG Hui-yong, SHEN Hong, DAI Ning
Abstract:
BIB (Blocked Impurity Band) detectors operating at deep cryogenic temperatures have significant application potential in fields such as infrared astronomy and space observation. However, studies on their temperature-dependent performance mechanisms remain relatively limited. In this work, a planar p-i-n long-wavelength infrared BIB detector based on high-purity germanium was fabricated using a near-surface treatment technique. The device exhibits excellent electrical and photoresponse performance at relatively elevated temperatures, achieving an increase of approximately 10?K in operating temperature compared to conventional BIB detectors. At 3.3?K, the reverse-bias dark current is as low as 15?pA. With increasing temperature, the blackbody detectivity shows a decreasing trend, but remains nearly constant below 15?K, reaching up to 3.5×1012?cm.Hz1?2.W?1. A current model incorporating photoexcitation, thermal excitation, and impact ionization processes was introduced to simulate the device behavior. The simulation results agree well with the experimental data and reveal that the primary degradation mechanism is the significant shrinkage of the depletion region at elevated temperatures, which reduces carrier collection efficiency. This study provides both theoretical support and experimental evidence for the structural design and performance optimization of BIB detectors for low-temperature infrared applications.
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Research on the Characteristics of Absorption Coefficient in the Low Absorption Region of InAs and GaSb Substrates Based on FTIR Spectroscopy Technology
Wangxiaozhen, TAN Zhi-yong, ZHANG Qing-ling-yun, LI Jian-mei, CHEN Yi-qiao, CAO Jun-cheng
Abstract:
GaSb and InAs demonstrate significant potential photoelectric applications in mid-wave infrared (3-5 μm) and long-wave infrared (8-12 μm) spectral regions. However, their weak optical absorption properties hinder accurate determination of absorption coefficients via conventional transmission spectroscopy due to multi-pass transmission effects. This study introduces a combined reflection-transmission analysis method based on Fourier-transform infrared spectroscopy (FTIR), achieving enhancement in measurement accuracy within the low-absorption regime (α<10 cm?1). For samples with doping concentrations of ND=2.46×1016 cm-3 (InAs) and ND=8.76×1016 cm-3 (GaSb), the analysis reveals that free carrier absorption in the 8-18 μm range is predominantly governed by acoustic phonon scattering and ionized impurity scattering. Notably, GaSb exhibits significantly enhanced scattering intensity compared to InAs, with a 10-fold increase in ionized impurity scattering coefficient and a 450-fold amplification in acoustic phonon scattering coefficient. The developed methodology provides a technical framework for determining absorption coefficients in low-absorption materials.
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Shortwave Infrared Polarization-based Aerial Small-UAV Target Detection via a Scale-Adaptive Local Extreme Measure
YANG Zheng-Ye, GONG Jin-Fu, XIN Jian-Qiao, WANG Shi-Yong, WU Ying-Yue, KANG Hua-Chao
Abstract:
Unmanned aerial vehicle (UAV) detection holds significant value in both civilian and military domains, however, conventional infrared detection systems remain vulnerable to background clutter interference. Infrared polarization imaging technology offers a novel solution by integrating polarization data with infrared imaging. However, the differences between polarization and infrared images introduces new problems to target extraction. Therefore, we propose a new detection algorithm based on scale-adaptive local extreme measure (ALEM). The algorithm introduces an enhanced SUSAN operator to quickly extract regions of interest (ROIs) while estimating potential target scales within these regions. Then present the ALEM algorithm, which is specifically designed to exploit the unique characteristics of polarization images. The algorithm effectively measures contrast by analyzing pixel neighborhood features within polarization images. Experimental results based on real-world polarization image dataset demonstrate that: the signal-to-noise ratio gain of the algorithm is increased by 2.7 times, the background suppression factor is increased by 8.6 times, and it can run at 20 fps. It exhibits excellent detection performance, robustness, and the capability for real-time detection.
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Independent Development of a Silicon Ultra-stable Optical Reference Cavity with High-Finesse
JIAO Dong-Dong, GAO Jing, WU Pan, DENG Xue, WU Meng-Fan, ZHANG Lin-Bo, XU Guan-Jun, ZANG Qi, Cui Jie, Dong Rui-Fang, LIU Tao, QU Bo, ZHANG Shou-Gang
Abstract:
This work presents the independent development of a silicon ultra-stable optical reference cavity with high-finesse. Silicon exhibits exceptional thermal stability, lower mechanical loss, and superior vibrational insensitivity. An optimized machining process effectively addresses key manufacturing challenges posed by silicon's brittleness and anisotropic properties. The three-stage polishing technology is utilized to achieve ultra-smooth surfaces with ? level roughness (RMS). The high-reflection film is produced using SiO2/Ta2O5 as the coating material via Ion Beam Sputter Deposition. A cavity linewidth measurement method demonstrates a finesse of ~340,000, comparable to top international counterparts. These results demonstrate China’s ability to independently develop high-performance silicon-based ultra-stable optical reference cavities. This advancement holds significance for precision applications like optical clocks and gravitational wave detection.
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A new algorithm for millimeter-wave cloud radar clutter rejection based on morphological improvement
LIU Qian-Chen, DI Hui-Ge, YUAN Yun, QUAN Chun-Hang, WANG Jia-Le, HOU Chen-Tao, HUA Deng-Xin
Abstract:
An improved multi-feature fusion scheme is proposed to address the problem of edge signal loss in existing clutter filtering methods for millimeter-wave cloud radar. A discriminative model is constructed based on reflectivity, time and vertical continuity for preliminary clutter identification, and then a morphological binary expansion operation is introduced to generate cloud edge candidate regions, and an accurate edge determination is performed with the help of domain analysis. It is verified that this scheme can effectively filter out clutter while retaining cloud edge signals more completely, solving the problem of edge signal loss in the existing clutter filtering scheme, improving the quality of millimeter-wave cloud radar data, and providing more reliable data support for atmospheric physics research and weather forecasting.
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A method for enhancing the performance of infrared filters based on rate-modulated deposition of germanium films
LIU Bao-Jian, LI Da-Qi, DUAN Wei-Bo, YU De-Ming, CAI Qing-Yuan, YU Tian-Yan, JIANG Lin, YANG Yu-Ting, ZHUANG Qiu-Hui, ZHENG Yu-Xiang
Abstract:
This study systematically investigated the influence of deposition rate on the structure, broadband optical properties (1.0–13.0 μm), and stress characteristics of Germanium (Ge) films. Additionally, a method for enhancing the performance of infrared filters based on rate-modulated deposition of Ge films was proposed. The optical absorption of Ge films in the short-wave infrared (SWIR) and long-wave infrared (LWIR) bands can be effectively reduced by modulating the deposition rate. As the deposition rate increases, the Ge films maintain an amorphous structure. The optical constants of the films in the 1.0–2.5 μm and 2.5–13.0 μm bands were precisely determined using the Cody-Lorentz model and the classical Lorentz oscillator model, respectively. Notably, higher deposition rates result in a gradual increase in the refractive index. The extinction coefficient increases with the deposition rate in the SWIR region, attributed to the widening of the Urbach tail, while it decreases in the LWIR region due to the reduced absorption caused by the Ge–O stretching mode. Additionally, the films exhibit a tensile stress that decreases with increasing deposition rate. Finally, the effectiveness of the proposed fabrication method for an infrared filter with Ge films deposited at an optimized rate was demonstrated through practical examples. This work provides theoretical and technical support for the application of Ge films in high-performance infrared filters.
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Measurement system calibration and radiation characteristic inversion based on infrared weak and small targets
liwenxiong, Shenjunli, Luzhenyu, Menshudong, Wuqingwen, Zhaoxiaoyan
Abstract:
With the widespread application of infrared detection technology in fields such as military reconnaissance, aerospace monitoring, and security early warning, infrared measurement systems play a critical role in infrared detection. In response to issues such as low calibration efficiency and significant environmental interference in the calibration and radiative property inversion of infrared measurement systems, this paper proposes a calibration and radiative property inversion method based on infrared weak small targets. A small-area blackbody source is used as a controllable radiation source to project infrared targets, and deep learning networks are employed for precise identification and gray-scale extraction of infrared weak small targets. Using this, a calibration model for the measurement system is established. Experimental results show that the method demonstrates good calibration stability within the temperature range of 298 K-308 K, with the absolute error of radiative property inversion controlled within ±2 K and the relative error of inversion temperature ≤ 0.5%. Regression analysis also indicates high temperature inversion accuracy (R2>0.94). Compared to traditional methods, the proposed method balances calibration efficiency and accuracy while extending the ability to invert the temperature field of targets. This research provides an effective solution for rapid calibration and high-precision radiative property analysis of infrared weak small targets.
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Modeling and Simulation of Infrared Polarization Characteristics of Aerial Targets Based on a Hybrid Radiation Polarization Model
YAN Kun-Na, Liu Hai-Zheng, Shi Ze-Lin, Zhao Ze-Hua, Zhao Chun-Yang
Abstract:
To address the need for infrared polarization detection in high-speed aerial targets, this paper presents a practical method for calculating and simulating the infrared polarization characteristics of these targets. Based on a hybrid radiative polarization model, an infrared degree of linear polarization (DoLP) calculation framework for aerial targets and an instantiation method for typical materials are developed. This model framework considers thermal emission, solar and environmental radiation reflections, and atmospheric transport effects. The deviation between the calculated and measured DoLP values for the material samples is less than 10%. Taking the high-speed SR-72 reconnaissance aircraft as an example, the simulation process is based on the reflection/radiance vector data generated by the polarization calculation model of the target material. The real-time simulation of the SR-72 target's infrared polarization characteristics is conducted with the Unity3D engine, and the image frame rate reaches 35 frames per second. The DoLP images of the SR-72 are simulated under varying conditions, including flight speed, detection band (MWIR/LWIR), and solar illumination. The variations in its polarization characteristics are subsequently analyzed. This study provides a data foundation and simulation support for infrared polarization detection and related assessment applications of aerial targets.
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Microwave/millimeter-wave multiband transmission lines, antennas, and passive components with large frequency ratios for integrated sensing and communication applications
LEl Bo-Jie, LI Jin, CHEN Si-Cheng, YAN Shu-Yao, YUAN Tao
Abstract:
The fundamental concepts, operating principles, and recent advancements in integrated sensing and communication (ISAC) are presented. A comprehensive review of multiband and large-frequency-ratio micro-wave/millimeter-wave transmission lines, antennas, and passive components—primarily filters and couplers—that are currently suitable for ISAC application scenarios is provided. Various implementation strategies and fabrication techniques for these multiband and high-frequency-ratio structures are comparatively analyzed. The technical characteristics, RF performance, and respective advantages and limitations of different design approaches are systematically summarized. This review offers a diverse and in-depth reference for the continued development of high-performance microwave/millimeter-wave front-end components tailored for ISAC applications.
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The Epitaxial Growth of InAs/GaInSb Long Wavelength Infrared Superlattice materials
LI Chen, JIANG Dong-Wei, XU Ying-Qiang, NI Hai-Qiao, WANG Guo-Wei, WU Dong-Hai, HAO Hong-Yue, NIU Zhi-Chuan
Abstract:
InAs/GaInSb Type-II superlattice (T2SL) materials exhibit significant advantages in long-wavelength (LWIR) and very long-wavelength infrared (VLWIR) detectors. By optimizing molecular beam epitaxy (MBE) growth parameters and interface control techniques, a 50-period short-period superlattice (SL) structure composed of 10-monolayer (ML) InAs/7ML Ga0.75In0.25Sb was successfully grown at the GaSb reconstruction transition temperature. High-resolution X-ray diffraction (HRXRD) characterization revealed a lattice constant of 6.108 ? and a period thickness of 53.53 ? for the superlattice, with deviations from theoretical design values below 0.2%. The lattice mismatch with the GaSb substrate was only 0.197%. Atomic force microscopy (AFM) measurements demonstrated a root mean square (RMS) surface roughness of 1.67 ?, while photoluminescence (PL) spectroscopy indicated a bandgap of 89.92 meV. Furthermore, a 12ML InAs/5ML Al0.8In0.2Sb superlattice barrier material was epitaxially grown, exhibiting a lattice mismatch of 0.067% with the GaSb substrate. Experimental results confirm that both the 10ML InAs/7ML Ga0.75In0.25Sb and 12ML InAs/5ML Al0.8In0.2Sb superlattices exhibit excellent lattice compatibility with the GaSb substrate. The presence of multiple satellite diffraction peaks and superior interface quality further validate the structural integrity of the materials. These findings provide a critical material foundation for the development of high-performance infrared detectors.
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Polarization angle scanning for wide-band millimeter-wave direct detection
WANG He-Yao, ZHAO Zi-Ran, QIAO Ling-Bo, GUO Da-Lu
Abstract:
Millimeter-wave (MMW) technology has been widely utilized in human security screening applications due to its superior penetration capabilities through clothing and safety for human exposure. However, existing methods largely rely on fixed polarization modes, neglecting the potential insights from variations in target echoes with respect to incident polarization. This study provides a theoretical analysis of the cross-polarization echo power as a function of the incident polarization angle under linear polarization conditions. Additionally, based on the transmission characteristics of multi-layer medium, we extended the depth spectrum model employed in direct detection to accommodate scenarios involving multi-layered structures. Building on this foundation, by obtaining multiple depth spectrums through polarization angle scanning, we propose the Polarization Angle-Depth Matrix to characterize target across both the polarization angle and depth dimensions in direct detection. Simulations and experimental validations confirm its accuracy and practical value in detecting concealed weapons in human security screening scenarios.
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Study on Regulation Characteristics of Photodetectors Based on MXenes/Microstructured Silicon Heterojunctions
LIAO Lu-Lu, XU Cai-Xia, LIU Gao-Rui, LIN Chang-Qing, LI Lu-Fang, SUN Hai-bin, YANG Xing, XU Long
Abstract:
Surface-microstructured silicon exhibits unique optical properties, demonstrating promising potential for applications in photoelectric sensors, solar cells, and related fields. To further explore the optoelectronic modulation effects based on its surface architecture, this study presents a novel heterojunction photodetector constructed by integrating MXene (Ti3C2Tx) with microstructured silicon substrate through spin-coating and other fabrication techniques.Comparative studies were conducted on commercial silicon, microstructured silicon, and Ti3C2Tx/microstructured silicon devices under varying wavelengths and optical power densities. The current-voltage (I-V) characteristics and photoresponse performance reveal that the Ti3C2Tx/microstructured silicon photodetector exhibits significantly superior external quantum efficiency (EQE) and responsivity across a broad spectral range of 200-1750 nm compared to commercial silicon and microstructured silicon detectors. Notably, in the near-infrared region (1100-1800 nm), the device demonstrates exceptional performance, achieving EQE exceeding 1000% and responsivity greater than 10 A/W. In contrast, commercial silicon photodetector in the same spectral range shows EQE below 10% and responsivity no higher than 0.3 A/W, while microstructured silicon photodetector exhibits EQE of below 15% and responsivity limited to 0.08 A/W. Further dynamic response and bias-dependent analyses indicate that the Ti3C2Tx coating, owing to its high conductivity and the built-in electric field formed at the heterojunction with microstructured silicon, significantly enhances detection capability from the NIR to MIR. Additionally, the response time is remarkably reduced from 38 ns to 20 ns. This heterojunction holds great promise for high-speed photodetection in optical communications, LIDAR, photoelectric sensing, and other advanced optoelectronic applications.
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Analysis and optimization of imaging characteristics of segmented planar imaging system based on checkerboard sampling lens array
Li Yan, He Yan, YU Qing-Hua1, SUN Sheng-Li
Abstract:
The study simulated imaging characteristics of a segmented planar imaging system. It investigated the influence of structural parameters on imaging results based on a checkerboard lens sampling array, and provided optimal parameters for the system. The work innovatively employed hyperspectral images to analyze the impact of interference spectral width on imaging quality in natural scenes, concluding that the allowable interference bandwidth in practical applications should not exceed 100 nm. The discussion on allowable bandwidth and error analysis based on real-world scenarios offered guidance for developing checkerboard-type imagers. These findings also provided universal insights applicable to all segmented planar imaging systems.
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Polarization Integrated Infrared Detector and Imaging Based on MetaLens Structure
Huang Hao-Jin, Wang Long, Zhou Jian, Wang Fangfang, Zhang Feng, Ying Xiang-Xiao, Tang Shou-Hai, Liu Yun-Meng, Chen Jian-xin, Zhou Yi
Abstract:
Due to the close pixel size and working wavelength of the focal plane polarization integrated infrared detector, diffraction effects cause severe crosstalk between adjacent pixels with different polarized light. A single traditional metal grating structure cannot achieve high extinction ratio polarization detection chips. This article proposes and designs a metasurface lens stacked polarization integrated infrared detector structure, studies the optical field convergence ability of metalens for different wavelengths of infrared light waves, prepares metastructural lenses and submicron grating structures, and integrates them with infrared focal planes. The polarization extinction ratio of the device exceeds 15:1, and dynamic and variable temperature objects are selected for polarization imaging experiments, demonstrating the imaging advantages of polarization integrated devices with focal planes.
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Terahertz detector based on side-gate AlGaN/GaN HEMT for resonant detection
JIN Chen-Yang, KANG Ya-Ru, LI Ye-Ran, YAN Wei, NING Jin, ZHAO Yong-Mei, LI Zhao-Feng, YANG Fu-Hua, WANG Xiao-Dong
Abstract:
In high-electron-mobility transistor (HEMT) terahertz detectors, an excessively wide gate can generate oblique modes in the channel, resulting in weakened resonant detection signals and a broadened resonance peak. To address this issue, a side-gate HEMT (EdgeFET) structure was proposed. A resonant detection model for the side-gate device was established based on the hydrodynamic equations of the two-dimensional electron gas (2DEG) in conventional HEMT. A side-gate HEMT detector was fabricated, and terahertz resonant detection experiments were conducted at 77 K. The experimental results indicated that EdgeFET demonstrated distinct resonant responses at 77 K, with the resonant responsivity reaching 3.7 times the maximum non-resonant responsivity. The experimental data were fitted using the theoretical model to validate its accuracy. These results strongly confirm the effectiveness of EdgeFET in enhancing the resonant performance of the detector, providing a new technological approach for the development of next-generation high-performance terahertz detectors.
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High-Performance Terahertz Detectors Based on Large-Area Semimetallic Platinum Telluride (PtTe2)
HUANG De-Bao, ZHOU Wei, HUANG Jing-Guo, QIU Qin-Xi, JIANG Lin, YAO Niang-Juan, GAO Yan-Qing, HUANG Zhi-Ming
Abstract:
Terahertz (THz) detectors, serving as the pivotal components for photoelectric conversion, constitute one of the fundamental building blocks in modern information society. Large-area PtTe2 thin films were synthesized via chemical vapor deposition (CVD), enabling the fabrication of THz detectors with varied channel lengths. Characterization results demonstrate that the device response exhibits linear dependence on both bias voltage and incident power, while the responsivity shows an inverse proportionality to channel length and operational frequency. The observed device characteristics align well with theoretical calculations based on the electromagnetic induced well (EIW) mechanism. Notably, EIW-based devices achieve a rapid response time of ~7.6 μs, with noise equivalent power (NEP) below 7.9×10-15 W/Hz0.5 and specific detectivity (D*) exceeding 9×1010 cm·Hz0.5/W under limited bias conditions. These performance metrics surpass those of previously reported semimetallic PtTe2-based detectors.
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Millimeter Wave Imaging of Range Migration Algorithm with Adaptive Background Filtering
CHENG Zhi-Hua, ZHOU Ran, WANG Meng, YU Tao, WANG Yu-Lan, YAO Jian-Quan
Abstract:
This paper proposes a novel Range Migration Algorithm (RMA) integrated with an adaptive background filtering method specifically designed for near-field millimeter-wave imaging scenarios where targets are in close proximity to background structures. This method simulate the attention distribution mode of the human visual system which is used in Artificial Intelligence (AI) and called Attention Mechanism. Based on the concept of static clutter filtering, the frequency-domain signals of the scanning aperture are divided into grid cells. Background scattering functions are established by analyzing the motion processes within each cell, and background interference is linearly filtered out. An analysis of the manifestation of background scattering interference within the algorithm is carried out, and the impact of the grid cell dimension on the imaging quality is investigated. Experimental results that the proposed method exhibits the capability to enhance the signal-to-noise ratio of both the target and the background. It effectively suppresses the background interference leading to a more prominent image, meanwhile without incurring a prohibitive computational load. The method offers a novel solution for improving the performance of millimeter-wave imaging technology in practical applications.
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Fabrication of flexible, low-loss and high-reliability PI mid-infrared hollow optical fiber and investigation of its CO2 laser transmission performances
YU Shuo-Ying, ZHU Run-Miao, LIU Sheng, ZHA Zhi-Peng, ZHANG Qing-Tian, HOU Guang-Ning, FEI Ying-Di, LIU Shao-Hua, JING Cheng-Bin, CHU Jun-Hao
Abstract:
Hollow optic fiber delivery of CO2 and other mid-infrared lasers still faces several challenges in terms of transmission loss, bending flexibility and reliability, which limits its applications in laser medicine, flexible industrial processing, and intelligent sensing. A flexible, low-loss mid-infrared hollow fiber with enhanced PI/Ag/AgI interfacial bonding strength has been developed by utilizing plasma activation of polyimide (PI) structural tubing and a dynamic liquid-phase deposition process. The results showed that after plasma treatment, the N-C bonds on the surface of PI were converted to N-O bonds and active groups such as carboxyl were formed. This results in enhancement of surface hydrophilicity and the interfacial bonding strength between PI and Ag/AgI layers (from level 0 to level 2) without noticeably increasing surface roughness. The as-fabricated PI hollow fiber (ID=2 mm) exhibited a low-loss transmission window within 8~15 μm wavelength range, achieving a linear transmission loss as low as 0.05 dB/m at 10.6 μm. When bent 180° with a radius of 20 cm, the loss increased only to 0.55 dB/m. The fiber could deliver a 30 W CO2 laser beam for 300 s at 150°C without damage. After 400 min of vibration testing and 120 min of high-low temperature aging (-196°C/150°C), the transmission loss remained stable, showing its value for practical applications.
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Peak Separation and Small Signal Modeling Analysis of Abnormal Shift in the transconductance curve in InAs Composite Channel HEMT
GONG Yong-Heng, CHEN Yu-Xuan, SHI Jing-Yuan, ZHANG Da-Yong, SU Yong-Bo, DING Wu-Chang, JIN Zhi, Ding Peng
Abstract:
In this work, 100 nm gate-length InP-based high electron mobility transistors (HEMTs) with a composite InGaAs/InAs/InGaAs channel are fabricated. DC measurements indicate that the InAs channel enhances transconductance but shifts the peak point toward lower?Vgs?under high?Vds?bias. Peak separation analysis reveals the DC transconductance curve is composed of two components: the gate-controlled transconductance and the impact-ionization-induced additional transconductance. Further analysis demonstrates that the anomalous shift originates from channel impact ionization intensity variation, which is caused by changes in the gate-drain electric field rather than carrier density in the channel. Two additional current sources were introduced in the small-signal model to characterize the impact-ionization-induced transconductance, and the numerical variation trends of their parameters are consistent with the peak separation results, which validates the mechanism's correctness. RF measurements confirm that the DC transconductance enhancement does not effectively improve RF characteristics, which is attributed to the ionization-induced transconductance having a time constant significantly larger than that of conventional transconductance components. These findings provide a theoretical foundation for controlling impact-ionization and improving effective transconductance, ultimately optimizing InAs channel HEMT design.
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Room-temperature Highly sensitive Bi2Te3 Terahertz Detector Based on Hot-carrier Photothermoelectric Effect
CAI Miao, WANG Xing-Jun, GUO Xu-Guang
Abstract:
High-performance uncooled terahertz (THz) detectors have a wide range of applications in many technological fields, such as high-rate data communications, real-time imaging, spectroscopy and sensing. However room-temperature THz detectors with high sensitivity and fast response capability are still rare. In recent years, the hot-carrier photothermoelectric (PTE) effect in two-dimensional (2D) materials has been found to be useful for room-temperature, high-speed, and highly sensitive photodetection in the THz and long-wave infrared radiation. In this study, the authors constructed a room-temperature THz detector based on the high-performance 2D layered thermoelectric material Bi2Te3, which employs a bow-tie antenna as an asymmetric light coupler and utilizes the hot-carrier PTE effect to achieve THz detection in zero-bias mode. The results show that the Bi2Te detector exhibits excellent THz detection performance, with a responsivity and noise equivalent power (NEP) of 0.45 A/W, 17 pW/Hz1/2, and a fast response time of 12 μs under 100 GHz radiation, respectively. This work demonstrates the promising application of Bi2Te3 THz detectors based on the hot-carrier PTE effect in realizing high-performance uncooled THz detectors.
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Continuous Wave Operation of Terahertz Quantum Cascade Wire Lasers with Dual Coupled Gratings
TAN Cheng, ZOU Ting-Ting, ZANG Shan-Zhi, WANG Kai, GAN Liang-Hua, CAO Chen-Tao, CHEN Bing-Qi, CHEN Hong-Tai, ZHANG Yue-Heng, FANG Yu-Long, XU Gang-Yi
Abstract:
We demonstrate terahertz quantum cascade (THz-QC) wire lasers based on dual coupled gratings that achieve continuous-wave (CW) operation near liquid nitrogen temperatures with a low-divergence Gaussian-like beam profile. Our configuration circumvents the effective refractive index constraint, significantly enhancing fabrication efficiency while retaining the key advantages of low power consumption and high heat dissipation efficiency. By engineering the photonic band structure of the coupled gratings, the laser operates on two supermodes. For Supermode #1, grating 1 serves as the master oscillator while grating 2 functions as a phased antenna array, featuring a collimated beam. For Supermode #2, grating 2 is the main oscillator and simultaneously provides a collimated beam, while grating 1 offers high reflectivity. Both supermodes exhibit high cavity quality factors and low beam divergence, achieved with a significantly reduced gain area. Experimentally, both supermodes were observed, and the optimized laser produces a collimated Gaussian beam with divergence angles of 12°×18° and an optical power of 1.04 mW. The threshold power consumption and thermal resistance are as low as 2.62 W and 8.5 mK/W/cm2, respectively, resulting in a maximum CW operating temperature of 78.0 K. This work offers a more accessible route for low-divergence, low-power-consumption, high-thermal-dissipation-efficiency THz-QCLs with enhanced CW operation at elevated temperatures.
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Field-Enhanced Ge-Based PIN Structured Blocked Impurity Band Infrared Detectors in Weakly Ionized Regions
Liu Chixian, Tianye-Chen, Zexin-Wang, Qingzhi-Hu, Wei-Dou, Xiaoyan Liu, Jingwei-Ling, Changyi-Pan, Jiaqi-Zhu, Peng-Wang, Huiyong-Deng, Hong-Shen, Ning-Dai
Abstract:
A novel germanium （Ge） based blocked-impurity-band （BIB） infrared detector with a planar PIN structure was developed, using near-surface processing technique to fabricate the target and electrode contact regions. The detector demonstrates significant rectifying characteristics, exhibiting extremely low dark current under reverse bias, and its working temperature is extended to 15 K. At this temperature, the detector maintains a stable detectivity of 6 × 1012 cm·Hz1/?·W?1 within the reverse bias voltage range of 0 to -5 V. Through band structure analysis, the dark current mechanism and the impact of temperature variation on optical response were discussed in detail, and the working principle based on the low-temperature weak ionization region was proposed. Additionally, tests of the detector’s blackbody response current and detectivity were systematically measured, and the mechanism of maintaining high performance at elevated working temperatures was clarified. The result provides innovative insights for enhancing the temperature performance of Ge-based BIB detectors and offers theoretical and experimental support for the design and application of future infrared detectors.
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Effect of mixed-period gratings on the photoresponse bandwidth of long-wavelength quantum well infrared photodetectors
TIAN Ya-Ping, LI Zhi-Feng, LI Ning, LI Xiang-Yang, XU Jin-Tong
Abstract:
The expansion of response bandwidth is an important direction in the development of quantum well infrared photodetectors. Using quantum well material with the peak response wavelength at 10.55 μm, the diffraction grating structure in the 30 μm center distance quantum well infrared detector is optimized, and six different combinations of the mixed-period gratings are obtained by mixing three grating structures with the period of 2.80, 3.50, and 4.25 μm within a single photosensitive pixel. Photoresponse spectroscopy tests show that the response bandwidth of the mixed-period grating can be broadened from 1.20 μm to 1.91 μm by up to 60% compared to a single-period grating, while the blackbody responsivity decreases by only 12%.
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The Study of Electrical Properties of Type-II InAs/GaSb Superlattices
xiangtaiyi, WANG NAN, HUANG MING, CHAI Xu-Liang, CHEN Jian-Xin
Abstract:
In order to investigate the electrical properties of InAs/GaSb type-II superlattices, a lattice-matched AlAsSb electrical isolation layer was grown between the GaSb substrate and the InAs/GaSb type-II superlattice epitaxial material to suppress the conductive effect of the substrate. Temperature-dependent Hall measurements revealed that the undoped superlattice exhibited N-type conductivity. As the P-type doping concentration increased, a compensation doping phenomenon was observed, with the occurrence of conductivity type transitions at 95 K and 230 K, respectively. Below the transition temperatures, P-type conductivity was exhibited, while above the transition temperatures, the material exhibited N-type conductivity. The phenomenon was analyzed using the Fermi level model, and the results indicated that the transition temperature for conductivity type changes increased with increasing doping concentration.
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High-Resolution Defect Detection in Optoelectronic Device via Scanning Imaging Technique
HU Er-Tao, LIU Jia-Wei, SHAO Peng, XIN Hao, CAI Qing-Yuan, DUAN Wei-Bo, CHEN Liang-Yao
Abstract:
Photocurrent scanning imaging (mapping) technology is a key technique in the research of solar cells and photodetectors. However, traditional galvanometer-driven beam scanning methods are limited by a restricted scanning range and image distortion. To address these shortcomings and meet the need for testing the photocurrent uniformity of large-area optoelectronic devices, an automated photocurrent mapping testing system has been developed based on optical component scanning. This system offers a large imaging range, high spatial resolution, high stability, and low cost. With its high-precision mode, it can achieve sub-micron geometric positioning (subdivision number 6400, scanning step size 0.625 μm), fulfilling both large-area scanning requirements and providing high-resolution testing. Moreover, its simple structure greatly reduces the overall cost of the mapping system. Using a silicon solar cell sample with surface covered by a “南” (south) character paper or a encoder strip mask, it was demonstrated that the scanning range exceeds 10×10 mm2, with a spatial resolution of 0.6 μm. The system was also used to characterize the surface photocurrent images of Cu?ZnSnS? and Cu?ZnSn(S,Se)? solar cells. The results show that the Cu?ZnSnS? cell contains more defects, while the Cu?ZnSn(S,Se)? cell exhibits a more uniform surface photocurrent response with fewer defects. These findings contribute to the optimization of solar cell fabrication processes.
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Research on stress adaptability of InAs/GaSb type Ⅱ superlattice long-wave focal plane infrared detectors
XUE Yong, XU Qing, HUANG Min, WANG Zhen, LIANG Zhao-Ming, XU Qing-Qing, BAI Zhi-Zhong, CHEN Jian-Xin
Abstract:
The superlattice long-wavelength infrared focal plane detectors operate at low-temperatures. The differences in the thermal expansion coefficients among the various material layers of the detectors can lead to deformation and generate thermal stress, which in turn affects the optoelectrical performances of the detector. This study designed two structural modules to achieve the regulation of stress in the superlattice detectors. The changes in dark current and spectral response of InAs/GaSb type II superlattice long-wave infrared focal plane detectors under different stress conditions were explored. The research indicates that within the stress range of -10.7 MPa to 131.9 MPa, the variations in the optoelectrical performance of the detector is small. The detector was subjected to a temperature shock test, and it demonstrated high reliability. Our research results provide guidance for the structural design of InAs/GaSb type II superlattice long-wave infrared focal plane detectors and offer a basis for their performance and reliability assessment.
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Study on the performance and parameters of interdigitated GaAs photoconductive terahertz radiation source
ZHANG yu-song, Shi Wei, LI yi-fan, Hou Lei, LI huan-lin
Abstract:
Optimizing the substrate material and electrode structure of photoconductive antennas is crucial to improving their performance in radiating terahertz waves. Compared with traditional photoconductive antennas (PCA), interdigitated photoconductive antennas (IPCA) can build multiple array elements in a smaller photosensitive area and have superior radiation performance. In this paper, six types of IPCA with different number of array elements and electrode gaps were designed and developed. The reverse electric field between adjacent electrodes was eliminated by blocking metal layers. The radiation characteristics and polarization characteristics of IPCA were compared with traditional PCA (parallel electrode antenna and bowtie antenna). The changes of the radiation characteristics of IPCA with the number of array elements, electrode gap, pump light energy and bias electric field were further studied. Experimental results show that the THz pulse radiation amplitude of the 40-element IPCA is 30 times higher than that of a single antenna.
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A Multi-Attention Mechanism U-Net Neural Network for Image Correction of PbS Quantum Dot Focal Plane Detectors
Hanting Wang, Di Yun-Xiang, Xingyu Qi, Yingzhe Sha, Yahui Wang, Lingfeng Ye, Weiyi Tang, Ba Kun, Wang Xu-Dong, Huang Zhang-Cheng, Chu Jun-Hao, Shen Hong, Wang Jian-Lu
Abstract:
Near-infrared image sensors are widely used in fields such as material identification, machine vision, and autonomous driving. Lead sulfide colloidal quantum dot-based infrared photodiodes can be integrated with silicon-based readout circuits in a single step. Based on this, we propose a photodiode based on an n-i-p structure, which removes the buffer layer and further simplifies the manufacturing process of quantum dot image sensors, thus reducing manufacturing costs. Additionally, for the noise complexity in quantum dot image sensors when capturing images, traditional denoising and non-uniformity methods often do not achieve optimal denoising results. For the noise and stripe-type non-uniformity commonly encountered in infrared quantum dot detector images, a network architecture has been developed that incorporates multiple key modules. This network combines channel attention and spatial attention mechanisms, dynamically adjusting the importance of feature maps to enhance the ability to distinguish between noise and details. Meanwhile, the residual dense feature fusion module further improves the network"s ability to process complex image structures through hierarchical feature extraction and fusion. Furthermore, the pyramid pooling module effectively captures information at different scales, improving the network"s multi-scale feature representation ability. Through the collaborative effect of these modules, the network can better handle various mixed noise and image non-uniformity issues. Experimental results show that it outperforms the traditional U-Net network in denoising and image correction tasks.
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Design and fabrication of pixel-level infrared metalens arrays for light field control
ZHANG Feng, WANG Fang-Fang, ZHOU Jian, YING Xiang-Xiao, ZHOU Yi, CHEN Jian-Xin
Abstract:
Metalenses，with their unique optical field modulation characteristics and remarkable advantages of high integration and miniaturization, have broad applications in the integrated imaging system of lightweight and small-sized optoelectronic chips. In this paper, a metalens structure for pixel-level integrated infrared focal plane applications was designed. The preparation of the structure adopted a method combining stepper lithography technology and Inductively Coupled Plasma (ICP) etching process. Through a systematic optimization of etching parameters, including gas flow rate, working pressure, and power, the loading effect was effectively suppressed and the standard deviation of the etching rate was decreased from 0.205% to 0.073%. Finally, a highly uniform metalens array was fabricated, with a pixel center distance of 30 μm, an array of 640×512, and a maximum aspect ratio of 3.42 of Si pillars. The focusing distance for 4.3 μm wavelength infrared light is 35 μm. The measured optical field convergence efficiencies, within radial ranges of 10 μm and 20 μm in the centra area at the focal length, are 66.4% and 84.9%, respectively. The optical field energy is increased by 5.98 times and 1.91 times, respectively, compared with that without the integrated metalens within the same area range. This study will provide the structural design and processing foundation for the integration of pixel-level metalens arrays with infrared chips.
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High performance multifunction integrated optic circuits base on thin-film lithium niobate
Qu Baiang, GUO Hong-Jie, YANG Yong-Kang, CHEN Wen-Bin, GUO Wen-Tao, TAN Man-Qing
Abstract:
This paper introduces an innovative Multifunction Integrated Optic Circuit (MIOC) design utilizing thin-film lithium niobate, surpassing traditional bulk waveguide-based MIOCs in terms of size, half-wave voltage requirements, and integration capabilities. By implementing a sub-wavelength grating structure, we achieve a Polarization Extinction Ratio (PER) exceeding 29 dB. Furthermore, our electrode design facilitates a voltage-length product (VπL) below 2 V·cm, while a double-tapered coupling structure significantly reduces insertion loss. This advancement provides a pivotal direction for the miniaturization and integration of optical gyroscopes, marking a substantial contribution to the field.
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Moving Mirror Speed Compound Control of the Fourier Transform Spectrometer Based on T-method
HUANG Ying, DUAN Juan, GUO Qian, DING Lei, HUA Jian-Wen
Abstract:
The Fourier transform spectrometer (FTS) is a precision infrared detection instrument. It adopts Michelson interference splitting, and the moving mirror is one of the core components. The uniformity and stability of the moving mirror’s speed directly affect the quality of the subsequent interferogram, so it is necessary to carry out high-precision motion control of the moving mirror. For some FTS with moving mirror in low-speed motion, the traditional M-method can no longer meet the requirements of speed measurement accuracy. In addition, when the moving mirror moves at a low speed, the speed stability is more easily affected by external mechanical disturbance. Based on the stability requirement of the low-speed moving mirror, this paper studies the motion control of the moving mirror based on the T-method measuring speed. It proposes a high-precision algorithm to obtain the measured and expected value of the velocity. By establishing the mathematical model and dynamic equation of the controlled object, the speed feedforward input is obtained, and then the compound speed controller based on the feedforward control is designed. The control algorithm is implemented by the FPGA hardware platform and applied to the FTS. The experimental results show that the error of the peak-to-peak velocity is 0.0182, and the error of the root mean square (RMS) velocity is 0.0027. To test the anti-interference ability of the moving mirror speed control system, 5mg sine excitation force is applied in the motion direction of the moving mirror on the FTS for frequency-fixed scanning. The frequency range is 2-200Hz. The experimental results show that under the excitation, the maximum error of the peak-to-peak velocity is 0.0679, and the maximum error of the RMS velocity is 0.0205. The speed stability of the moving mirror can still meet the performance requirements of the FTS. This design provides a technical means for realizing the speed control of the moving mirror with low speed and high stability. Also it makes the FTS have wider applications.
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Aircraft contrail detection based on satellite-borne hyperspectral images
XIE Shu-Xin, LI Peng-Fei, ZHAO Si-Wei, LIAN Xiao-Ying, SUN De-Xin
Abstract:
Existing methods for detecting aircraft contrails primarily relied on the radiance or temperature differences between specific channels in multispectral images. However, they did not fully exploit the potential of spectral features. The advancement of satellite-borne hyperspectral imaging technology has provided a new data foundation for aircraft contrail detection. This study explored a detection algorithm for potential aircraft contrails using shortwave infrared hyperspectral images from the GF-5 AHSI. A spatial-spectral feature extraction method was proposed, which leveraged the complementary nature of spatial and spectral information in hyperspectral images. The method achieved an accuracy of over 97% and a false alarm rate of less than 2% on GF-5 hyperspectral image data. This work offers valuable insights for future research.
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Bound States in the Continuum for Encoded Imaging
Abstract:
Artificial structures known as metasurfaces are used extensively to control the propagation, phase, amplitude, and polarization of light by finely adjusting the characteristics of electromagnetic waves on a sub-wavelength scale. In this work, we suggest a Bound States in the Continuum (BIC) structure based on a metallic metasurface. We were able to achieve a notable BIC peak at a frequency of 0.8217 terahertz (THz) by carefully modifying the metallic structures utilizing CST and COMSOL tools.We discovered through multi-level expansion analysis that the electric dipole (ED) is primarily responsible for this structure's resonant characteristic. We created and put into operation an image system that operates at 0.8217 THz by utilizing the features of BIC. According to experimental data, the imaging system offers outstanding sensitivity and resolution, indicating great promise for terahertz imaging. In addition to offering fresh concepts for the creation of metasurface-based BIC structures, our research gives useful references for the advancement of high-performance terahertz imaging technologies.
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Cavity-enhance absorption spectroscopy for the measurement of Oxygen concentration
SONG Jun-Ling, RAO Wei, WANG Lin-Yan, ZHU Xiao-Hui, WANG Dian-Kai, FENG Gao-Ping
Abstract:
A high-performance oxygen detection system enables real-time online monitoring of critical parameters such as oxygen concentration and flow velocity within the engine, ensuring optimal operational efficiency. In flow field tests for engines such as scramjet and aviation engines, the complex environment characterized by high temperatures, pressures, and velocities, along with limited measurement space, poses significant challenges for accurate flow field diagnostics. To address these challenges, a device for measuring oxygen component concentration based on cavity-enhanced absorption spectroscopy (CEAS) was developed. The device features an embedded optical probe design and incorporates multi-directional adjustment mechanisms at both the transmitting and receiving ends to facilitate precise optical path alignment, enhancing its applicability in engineering experiments. Experimental results demonstrated that, in a static environment, the measured oxygen concentration was 20.846?0.97%.. In shock tube experiments, the system successfully captured three distinct states: before the arrival of the incident shock wave, after the passage of the incident shock wave but before the reflected shock wave arrived, and after the passage of the reflected shock wave. The measured oxygen concentration data were consistent with theoretical predictions.
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Silicon valley photonic crystal Mach-Zehnder thermo -optic modulator
ZHANG Xin-Yan, LIN Han, FEI Hong-Ming
Abstract:
Thermo-optic modulators are key components of optical communication systems, and their performance directly affects system efficiency. With the development of silicon optothermonic technology, silicon thermo-optic modulators have been widely used in optothermonic chips. Conventional silicon optical modulators are large in size and have high losses. In recent years, researchers have proposed to use the slow light effect of photonic crystals to reduce the footprint of modulators. Related studies have shown that these devices have advantages, such as small size and low driving voltage. However, the optical transmittance of thermo-optic modulators based on photonic crystals is still affected by defects caused by fabrication errors. Valley photonic crystal optical waveguides can achieve scattering-immune high-efficiency unidirectional transmission, providing a new venue for realizing high-performance photonic devices. In this paper, a new silicon thermo-optic modulator based on a valley photonic crystal Mach-Zehnder interferometer (MZI) is designed. The electrical heating mechanism is introduced on one of the waveguides of the MZI. The thermo-optic effect modulates the refractive index to achieve precise phase modulation of the transmitted light. The thermo-optic modulator device has a small footprint of only 9.26 μm × 7.99 μm, which can achieve a high forward transmittance of 0.91, an insertion loss of 0.41 dB, and a modulation contrast of 11.75 dB. It can also be experimentally fabricated using complementary metal oxide semiconductor (CMOS) technology, so it will have broad application prospects. This modulation principle can be widely used in designing different thermo-optic modulation devices.
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Study of Dual-Frequency-Band Millimeter-Wave Extended Interaction Klystron Based on Dual-2π Mode
XU Che, LU Jia-Ni, TANG Yong-Liang, TANG Xian-Feng
Abstract:
This paper proposes a novel dual-frequency-band millimeter-wave extended interaction klystron amplifier (EIKA). It is primarily based on the multimode operating mechanism of dual-2π mode. This design integrates a broadband traveling-standing-wave mode input cavity with a dual-2π standing-wave mode output cavity, resulting in a compact slow-wave structure design that efficiently operates within a total circuit length of approximately 24 mm. Particle-in-cell simulation results reveal that under a 15.6 kV, 1 A electron beam and a uniform 0.6 T magnetic field, the device achieves output power for 183-1024 W across a broadly 1.20 GHz bandwidth, spanning 93.76-94.96 GHz. Remarkably, it facilitates dual-band output in both lower-2π and upper-2π bands, delivering maximum gains of 37.09 dB (1024.10 W at 93.90 GHz) and 35.75 dB (752.20 W at 94.84 GHz), with -3 dB bandwidths of 0.33 GHz and 0.20 GHz, respectively. The effectiveness for the dual-2π mode design is further confirmed through a cold-test experiment using the perturbation method. This experiment demonstrated typical dual-2π mode field distribution profiles, affirming the design's efficacy.
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Broadband high-extinction-ratio nonvolatile optical switch based on phase change material
LIANG Kai, YUE Wen-Cheng, XU Fan, ZHU Qian-Nan, ZHANG Jian-Min, WANG Shu-Xiao, CAI Yan
Abstract:
In this paper, we present a broadband, high-extinction-ratio, nonvolatile 2×2 Mach-Zehnder interferometer (MZI) optical switch based on the phase change material Sb2Se3. The insertion loss (IL) is 0.84 dB and the extinction ratio (ER) reaches 28.8 dB at the wavelength of 1550 nm. The 3 dB bandwidth is greater than 150 nm. Within the 3 dB bandwidth, the ER is greater than 20.3 dB and 16.3 dB at bar and cross states, respectively. The power consumption for crystallization and amorphization of Sb2Se3 is 105.86 nJ and 49 nJ, respectively. The switch holds significant promise for optical interconnects and optical computing applications.
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Research progress of active metasurface for intelligent radar stealth
WANG Dong-Shu, LIU Tong-Hao, WANG Liu-Ying, LIU Gu, CHENG Hai-Qing, CHENG Meng-Zhong, GE Chao-Qun, WANG Long, WANG Bing, XU Ke-Jun
Abstract:
The new active metasurface has the advantages of small size, light weight and easy integration, so it has an important application prospect in weapon radar intelligent stealth. Based on this, focusing on the requirements of radar intelligent stealth for current weapons and equipment, this paper expounds the methods, approaches and performance advantages of active metasurface in electromagnetic wave regulation, reviews the development history of various active metasurface, and summarizes the research status and future development direction of active metasurface for radar intelligent stealth. It provides the relevant theoretical basis and design reference for the wide application of active metasurface in intelligent stealth of weapon equipment radar.
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Effect of Extrinsic resistances on Noise performance for Deep Submicron MOSFET
GAO HANQI, Jin Jing, Zhou JianJun
Abstract:
This paper investigates the impact of extrinsic resistances on the noise performance of deep submicron MOSFETs using the noise correlation matrix method. Analytical closed-form expressions for calculating the four noise parameters are derived based on the small-signal and noise-equivalent circuit models. The results show strong agreement between simulated and experimental data for MOSFETs with a gate length of 40 nm and dimensions of 4×5 μm (number of gate fingers × unit gate width).
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Anisotropic Tetratellurium-Iridium-Nibium Terahertz Detector
Liu Yuan, Yang Si-Jia, XU Yong-Jiang, SHEN Yun, DENG Xiao-Hua
Abstract:
Topological semimetal materials have garnered significant interest due to their distinctive electronic structures and unique properties. They serve as a foundation for exploring various physical phenomena, including the anomalous Hall effect, topological phase transitions, and negative magnetoresistance, while also offering potential solutions to the "THz Gap." This study focuses on the type-II Weyl semimetal tetratellurium iridium niobium (NbIrTe4) terahertz detector, which exhibits a responsivity of 4.36 A/W, a noise equivalent power of 12.34 pW/Hz1/2, and an anisotropic resistance ratio of 32 at room temperature. This research paves the way for achieving high-performance terahertz detection at room temperature and serves as a reference for investigating the Weyl semimetal.
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Strongly Coupled Electro-optical Tunable 780 nm Ultra-Narrow Linewidth Laser Source
Xue Kai, RONG Jia-Min, XING Guo-Hui, XUE Jun-Jie, LIU Wen-Yao, ZHOU Yan-Ru, XING En-Bo, TANG Jun, LIU Jun
Abstract:
Highly matched and precisely locked to the absorption lines of rubidium (Rb) atoms, 780 nm lasers play a crucial role in fields such as quantum computing, precision measurements, and high-sensitivity sensing, with clear requirements for strong coherence and fast tunability. In this paper, based on the self-injection locking and ultra-high quality factor Whispering gallery mode (WGM) cavity, a 780 nm narrow linewidth (23.8kHz) tunable laser with a single longitudinal mode output is verified. More importantly, benefiting from the optimized combined coupling coefficient K and via the lithium niobate electro-optic effect, the laser frequency detuning is effectively improved, with the experimental tuning range reaching 110 pm and the tuning efficiency of 6.4 pm/V. This work provides a high-performance design solution for fast-tunable narrow-linewidth lasers for applications in the near-infrared range, which is expected to play an essential role in the future.
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The Investigation of Concentrated Triple-Junction Solar Cells Based on InGaAsP
ZHANG Jicheng, GUAN Weiwei, SUN Qiangjian
Abstract:
The InGaAsP material with an energy bandgap of 1.05 eV was grown on InP substrates by all-solid-state Molecular Beam Epitaxy (MBE) technique. The material had no mismatch dislocations between the substrate and the epitaxial layer, and also exhibited high interface quality and luminescent quality. Based on InGaAsP material, single-junction InGaAsP solar cells were grown on InP substrates, and GaInP/GaAs dual-junction solar cells were grown on GaAs substrates. These two separate cells were then bonded together using wafer bonding technology to fabricate a GaInP/GaAs/InGaAsP triple-junction solar cell. Under the AM1.5G solar simulator, the conversion efficiency of the GaInP/GaAs/InGaAsP wafer-bonded solar cell is 30.6%, achieving an efficiency of 34% under concentration. The results indicate that MBE can produce high-quality InGaAsP material, and room-temperature wafer bonding technology holds great potential for the fabrication of multi-junction solar cells.
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Research on the Metrological Calibration Technology Scheme of Brightness Temperature for the Space-borne Microwave Radiometer Calibration Target
GAO Qing-Song, LI De-Tian, TAO Yuan, YANG Lei, ZHANG Hu-Zhong, MA Dong-Tao, PENG Miao-Miao, JIN Ming, GUO Qiang, JIANG Shi-Chen, LI Yi-Nan, CHENG Chun-Yue, LI Xue
Abstract:
This paper addresses the application requirements for the brightness temperature calibration of the hot calibration target for spaceborne microwave radiometers. Based on the temperature gradient characteristics of the absorbing coating of the calibration target and the mechanism of brightness temperature deviation, combined with practical temperature measurement methods and experimental means, a brightness temperature metrological calibration technology solution applicable for in-orbit use is studied. Given the current background of high emissivity design and determination technology of the calibration target being basically perfected, the paper focuses on summarizing the methods for determining the temperature gradient characteristics of the calibration target coating. The goal is to construct an in-orbit available brightness temperature calibration method that uses multiple parameters, such as the temperature measurements of the metal inner cone of the calibration target and the temperature measurements near the radiation aperture of the calibration target. Based on feasible electromagnetic simulation technology, thermal simulation technology, platinum resistance and infrared temperature measurement techniques, the paper preliminarily summarizes the implementation path of the brightness temperature calibration technology system for spaceborne calibration targets. This involves first constructing a basic brightness temperature calibration model considering uniform background brightness temperature and improving the mapping relationship from the inner cone temperature of the calibration target and the equivalent background brightness temperature to the longitudinal temperature gradient of the coating. Subsequently, an application model for brightness temperature calibration considering the installation environment is constructed, improving the mapping relationship from the temperature measurements of the inner cone and the radiation aperture area of the calibration target to the brightness temperature deviation of the calibration target. Finally, the validation and application of the brightness temperature calibration model are discussed.This work serves as an important technical basis and reference for further improving the accuracy of the calibration target's brightness temperature and even developing space microwave radiometric measurement benchmarks.
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Review on infrared polarization image fusion methods
zhengjinjiang, LI Xiao-Xia, ZHAO Da-Peng, CHEN Yi, WU Meng-Xing
Abstract:
Infrared polarization image fusion can fully utilize the polarization information of the scene, compensate for the disadvantage of infrared intensity images in describing high-frequency information such as scene contour edges and texture details, and has unique advantages in target detection and recognition, background noise suppression, and counter camouflage. The article summarized the research progress of infrared polarization image fusion technology from two aspects: single algorithm image fusion and multi-algorithm combination image fusion. It analyzed the design ideas of typical algorithms and summarized the advantages and disadvantages of each algorithm. Based on the current trend where single algorithm serves as the mainstream and multi-algorithm combination as the development trend for infrared polarization image fusion, this paper anticipates its potential future development direction.
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Lightweight Remote Sensing Multimodal Large Language Model Based on Knowledge Distillation
ZHANG Xin-Yue, FENG Shi-Yang, WANG Bin
Abstract:
Remote sensing multimodal large language models (MLLMs), which integrate rich visual-linguistic modal information, have shown great potential in areas such as remote sensing image analysis and interpretation. However, existing knowledge distillation methods primarily focus on the compression of unimodal large language models, neglecting the alignment of features across modalities, thus hindering the performance of large language models in cross-modal tasks. To address this issue, a lightweighting method for remote sensing MLLMs based on knowledge distillation is proposed. This method achieves effective alignment of multimodal information by aligning the outputs across modalities at the feature level. By introducing the reverse Kullback-Leibler divergence as the loss function and combining optimization strategies such as teacher mixed sampling and single-step decomposition, the generalization and stability of the student model are further enhanced. Experimental results demonstrate that the proposed method achieves higher accuracy and efficiency in four downstream tasks of remote sensing image scene classification, visual question answering, visual localization, and image description, significantly reducing the number of model parameters and the demand for computational resources, thereby providing a new solution for the efficient application of MLLMs in the field of remote sensing.
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2002,21(3):161-166
Abstract:
A segmentation model that combines the Mumford Shah(M S) model and narrow band scheme of level set was presented. The disadvantage of Mumford Shah model is computationally time consuming. In each step of its iteration, the data of whole image have to be renewed, which is unbearable for segmentation of large image or 3D image. Therefore, a fast segmentation model was introduce, which combines the M S model and narrow band scheme by a new initialization method. The new initialization method is based on fast marching method, and the computing time decreases to O(N) . In each step of iteration, the new segmentation model only deals with the data in a narrow band instead of the whole image. The experiments show that the two models can obtain almost the same segmentation result, but the computing time of new narrow band M S model is much less than that of M S model.
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GUO Li Xin 1) KIM Che Young 2)
2003,22(2):132-136
Abstract:
根据粗糙面基尔霍夫小斜率近似研究了脉冲波入射时实际海谱分布的一维分形海面的电磁散射。分析了毫米波入射时不同分维、入射角和入射中心频率下双频散射截面的散射角分布。结果表明分形海面的双频散射截面在镜反射方向有最大的相关带宽，随着海面分维的减小、入射中心频率和入射角的增加，该相关带宽是增大的。对于入射功率为δ函数时的散射波功率是一个具有一定脉冲展宽的散射脉冲，且脉冲展宽与相关带宽成反比关系。
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2001,20(3):184-188
Abstract:
测量了几种不同处理的Cd1-xZnxTe(x=0.04)表面的傅里叶变换拉曼散射光谱和电流－电压（I－V）特性。通过分析拉曼光谱反Stokes分量，并与表面I－V特性进行比较，结果表明与表面处理相联系的晶格声子的行为反映了表面完整性的变化，Te沉淀是影响表面质量的关键因素，并对有关表面处理方法的实际应用进行了讨论。
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FuY ChiragwandiZ GoethbergP WillanderM
2003,22(6):401-405
Abstract:
We have studied the optical spectra of low-dimensional semiconductor systems by calculating all possible optical transitions between electronic states. Optical absorption and emission have been obtained under different carrier population conditions and in different photon wavelengths. The line-shapes of the peaks in the optical spectrum are determined by the density of electronic states of the system, and the symmetries and intensities of these peaks can be improved by reducing the dimensionality of the system. Optical gain requires in general a population inversion, whereas for a quantum-dot system, there exists a threshold value of the population inversion.
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HU Zhi Gao WANG Gen Shui HUANG Zhi Ming CHU Jun Hao
2002,21(3):175-179
Abstract:
采用溶胶－凝胶法在石英玻璃衬底上制备出均匀透明的无定形PbTiO3薄膜，并对其 光学性质进行了详细的研究，发现其折射率的波形符合经典的Cauchy函数。由半导体理论计算得到无定形的PbTiO3薄膜的光学禁带宽度为3．84eV.FTIR透射光 谱研究表明无定形PbTiO3薄膜在中红外波段没有吸收峰出现，对于在550℃下 快速热退火得到的PbTiO3薄膜，通过远红外反射光谱测量，观察到了6个约外活性声子膜。
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ZHANG Qian, TANG Li-Bin, LI Ru-Jie, XIANG Jin-Zhong, HUANG Qiang, LIU Shu-Ping
2019,38(1):79-90 ,DOI: 10.11972/j.issn.1001-9014.2019.01.014
Abstract:
With the rapid development of graphene industry, graphene oxide has attracted much attention as an important intermediate product for the preparation of graphene. Due to its excellent physical and chemical properties, it has been widely used in multitudinous fields. Various structural models, preparation methods, properties and related applications, as well as the reduction of graphene oxide are summarized. The choice of oxidants and reduction agents were found to be important in the reaction. The basic selective principles are discussed after comparing various methods. Finally, it is pointed out that there are still some problems to be solved in the preparation and reduction of graphene oxide. The prospect of graphene oxide on its development and influence will also be evaluated.
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LIU Yu, LIN Zhi-Cheng, WANG Peng-Fei, HUANG Feng, SUN Jia-Lin
2023,42(2):169-187 ,DOI: 10.11972/j.issn.1001-9014.2023.02.005
Abstract:
Photodetectors play a key role in many applications， such as remote sensing， night vision， reconnaissance， medical imaging， thermal imaging， and chemical detection. With the increasing complexity of photoelectric detection tasks， photodetectors working in different bands are gradually integrated into broad spectral detection for the same scene. Limited by the volume and task module of the integrated system， conventional broad spectral detection tasks often require multiple detectors working in different bands to perform together， which greatly increases the complexity of detection system. Therefore， photodetector enabling to response ultra-broadband radiation （UV-vis-IR-THz） has gradually become a subject of great interest in recent years. However， there have been no reports on the review of ultra-broadband photodetectors so far. Hence， this review systematically summarizes the research progresses of ultra-broadband photodetectors in the past ten years. The factors affecting the response performance of photodetectors and the main types of common photodetectors are described first， and then the research progress， development status and challenges are reviewed and suggestions about the future research directions of ultra-broadband photodetectors are also provided.
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2022,41(2):395-412 ,DOI: 10.11972/j.issn.1001-9014.2022.02.004
Abstract:
The industrialization of copper indium gallium selenide （Cu（In，Ga）Se2， CIGS） solar cells has attracted worldwide attention. As a thin film solar cell with high conversion efficiency， its efficiency can be compared with that of crystalline silicon solar cell， and the highest efficiency reaches 23.35% at present. For small-area laboratory solar cells， the main research focus is to accurately control the stoichiometric ratio and efficiency of absorption layer. For industrial production， besides stoichiometric ratio and efficiency， cost， reproducibility， output and process compatibility are very important in commercial production. The research progress of different preparation processes， gradient control of absorption layer composition， post-deposition treatment of alkali metal， wide band gap cadmium-free buffer layer， transparent conductive layer and flexible substrate were reviewed. From the perspective of the efficiency of CIGS solar cells， the transfer of record-breaking high-efficiency solar cell technology in the laboratory to the average industrial production level brings obvious challenges.
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WU Yan 1), 2) ZHANG Li Ming 2)
2002,21(3):189-194
Abstract:
Based on bias variance model, a novel method of dynamically tuning the regularization coefficient by fuzzy rules inference was proposed. The fuzzy inference rules and membership functions were effectively determined. Furthermore, the method was compared with the traditional BP algorithm and fixed regularization coefficien's method. The result is that the proposed method has the merits of the highest precision, rapid convergence and best generalization capacity. The capacity proposed method is shown to be a very effective method by several examples simulation.
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YE Zhen-Hua, LI Hui-Hao, WANG Jin-Dong, CHEN Xing, SUN Chang-Hong, LIAO Qing-Jun, HUANG Ai-Bo, LI Hui, ZHOU Song-Min, LIN Jia-Mu, PAN Jian-Zhen, WANG Chen-Fei, CHEN Hong-Lei, CHEN Lu, WEI Yan-Feng, LIN Chun, HU Xiao-Ning, DING Rui-Jun, CHEN Jian-Xin, HE Li
2022,41(1):15-39 ,DOI: 10.11972/j.issn.1001-9014.2022.01.001
Abstract:
Infrared photon detection technology usually works in the passive sensing mode and contains the advantages of long acting-distance， good anti-interference， excellent penetration of smoke and haze， and all-day operation， which has been widely used in space remote sensing， military equipment， astronomical detection and other aspects. So far， the second-generation and the third-generation infrared photon detectors have been deployed widely. The high-end third-generation infrared photon detectors have been gradually promoted to practical application. The fourth generation and more forward-looking research including new concept， new technology， and new device has been proposed. This paper focuses on the research status of infrared technology at home and abroad， emphatically introducing the hotspots and development trends of infrared photon detectors. Firstly， the concept of SWaP3 is introduced due to tactical ubiquity and strategic high performance. Secondly， the high-end third-generation infrared photon detectors with ultra-high spatial resolution， ultra-high energy resolution， ultra-high time resolution and ultra-high spectral resolution are reviewed. Technical characteristics and implementation methods of ultimate-performance infrared detectors are analyzed. Then， the fourth-generation infrared photon detector based on the artificial micro-structure is discussed. The realization approaches and technical challenges of multi-dimensional information fusion such as polarization， spectrum and phase are mainly introduced. Lastly， highly innovative trends of future detectors are discussed according to upgradation from on-chip digitization to on-chip intelligence.
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SUN Xiao-Jie, GAO Meng-Yu, ZHENG Yu-Xiang, ZHANG Rong-Jun, WANG Song-You, LI Jing, CHEN Liang-Yao
2022,41(1):230-247 ,DOI: 10.11972/j.issn.1001-9014.2022.01.017
Abstract:
Radiative cooling has been a hotspot for scientific research recently. As a passive cooling method， it uses outer space as heat sink， and has the advantage of low or even zero energy consumption. It has high potential in many applications such as building air conditioning， solar cell cooling， comfortable clothing， etc. This paper briefly reviews the development history and principles of radiative cooling， systematically introduces the structures and materials of radiative cooling， summarizes the design， preparation and characterization methods of radiative cooling materials， and also summarizes relevant application fields. The future of radiative cooling materials and technology is proposed at the end of this paper.
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XU Yun, WANG Yi-Ming, WU Jing-Zhu, ZHANG Xiao-Chao
2010,29(1):53-56
Abstract:
NIRS was used in rapid qualitative and quantitative detection for melamine of pure milk in this paper. Experiment was conducted by preparing two groups pure milk samples which melamine content is different for qualitative analysis and quantitative analysis. By combining NIRS technology with the cluster analysis method, A effective classification can be made on the two kinds of milk samples with and without melamine; To achieve this, spectrum pretreatment and wave length choice methods were employed before model optimization. The results showed that NIR models of predicting melamine content in pure milk has good stability and predictive ability.This paper suggested that NIR could be used as a quick, green and convenient method for predicting melamine content of dairy.
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CAI Hu, CHENG Zu-Hai, ZHU Hai-Hong, ZUO Du-Luo
2006,25(3):165-169
Abstract:
利用场发射扫描电子显微镜对TEA-CO2强激光脉冲辐照的Hg0.8Cd0.2Te晶片表面进行了观察,并利用电镜自带的能谱分析仪对其表面进行了成分分析.在单脉冲能量为1.91J,峰值功率密度为2.63×107W/cm2的脉冲CO2激光辐照下,晶片表面呈现出熔融迹象,且晶片表面的化学组分比发生明显的变化.理论与实验研究结果表明激光急速加热使晶体表面的Hg-Te键破坏,从而导致Hg损失,而Hg损失程度与热作用过程的时间有关.随着脉冲作用次数的增加,多脉冲的连续作用使Hg损失加剧,晶片表面成分变化更加突出.
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CHENG Jian, ZHOU Yue, CAI Nian, YANG Jie
2006,25(2):113-117
Abstract:
The particle filter is an effective technique for the state estimation in non-linear and non-Gaussian dynamic systems. A novel method for infrared object robust tracking based on particle filters was proposed. Under the theory framework of particle filters, the posterior distribution of the infrared object is approximated by a set of weighted samples, while infrared object tracking is implemented by the Bayesian propagation of the sample set. The state transition model is chosen as the simple second-order auto-regressive model, and the system noise variance is adaptively determined in infrared object tracking. Infrared objects are represented by the intensity distribution, which is defined by the kernel-based density estimation. By calculating the Bhattacharyya distance between the object reference distribution and the object sample distribution, the observation probability model is constructed. Experimental results show that our method is effective and steady.
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HE Yang, YANG Jin, MA Yong, LIU Jian-Bo, CHEN Fu, LI Xin-Peng, YANG Yi-Fei
2016,35(5):600-609 ,DOI: 10.11972/j.issn.1001-9014.2016.05.015
Abstract:
Traditional fire detection methods use the high temperature emission characteristics in mid or thermal infrared bands of the MODIS or AVHRR data to extract burning area. It is very hard for these methods to identify small fire regions such as sub-pixel due to the limitation of spatial resolution. Recently researchers have found that shortwave infrared (SWIR) data can also be used to identify and detect high temperature targets. Compared with the thermal infrared data, SWIR has a big discrimination against different features with different temperature. Thus it can identify accurately the location of high temperature targets. In this paper, we acquired fire point products by using Landsat-8 OLI data which has spatial resolution up to 30 m. The main procedure includes two steps. The improved Normalized Burning Ratio Short-wave(NBRS) is calculated at first to adaptively acquire suspected fire points based on the spectral characteristics of fire points in the near infrared and shortwave infrared. Then most false positive points are excluded based on the relationship between peak value in shortwave infrared band of fire points. This algorithm is capable of detecting the burning area around 10% in one pixel. With the premise of avoiding the interference of cloud and constructions, it can also keep a nearly 90% accuracy and low missing rate around 10%.
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JIANG Wei Dong CHEN Zen Ping ZHUANG Zhao Wen GUO Gui Rong
2001,20(2):111-116
Abstract:
The simulation methods of radar clutter with given amplitude distribution and power spectrum were described, and the simulation results of radar clutter were given. A scattering center model of frequency domain of radar target was presented under the clutter environment and its solution method was studied. Finally, the experimental results of simulation data and the measurement data of aircraft scale model were given.
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2001,20(3):207-210
Abstract:
A novel pixel level image fusion scheme was presented based on multiscale decompositon. First, the wavelet transform is used to perform a multiscale decomposition of each image. Then, the wavelet coefficients of fused image are constructed using multiple operators according to different fusion rules. This approach is successfully used to fuse the infrared and visible light images. The experimental results show that the fusion scheme is effective and the fused images are more suitable for human visual or machine perception.
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2008,27(2):123-128
Abstract:
多数传统分类算法应用于高光谱分类都存在运算速度慢、精度比较低和难以收敛等问题.本文从支持向量机基本理论出发建立了一个基于支持向量机的高光谱分类器,并用国产OMIS传感器获得的北京中关村地区高光谱遥感数据进行试验,分析比较了各种SVM核函数进行高光谱分类的精度,以及网格搜寻的方法来确定C和愕闹?结果表明SVM进行高光谱分类时候径向基核函数的分类精度最高,是分类的首选.并且与神经网络径向基分类算法以及常用的最小距离分类算法进行比较,分类的精度远远高于SVM分类算法进行分类的结果.SVM方法在高光谱遥感分类领域能得到广泛的应用.
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2010,29(1):69-74
Abstract:
Image segmentation is one of the difficult problems in computer vision research. Recently spectral clustering has a wide application in pattern recognition and image segmentation. Compared with traditional clustering methods, it can cluster samples in any form feature space and has a global optimal solution. Originating from the equivalence between the spectral clustering and weighted kernel K-means, the authors proposed a spectral clustering algorithm with spatial constraints based on the spatially coherent property of images, also named continuous property. The spatially coherent property means that pixels in the neighbor region should share the same label assignment with the centre one with a high probability. The algorithm adds a term of spatial constraints to the objective function of weighted kernel K-means and makes the minimization of the objective function be equivalent to the spectral clustering through approximation. Experimental results show that our proposed algorithm outperforms the traditional spectral clustering in image segmentation.
