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SUN Jia-Hao, CHENG Ru-Min, GUO Kai, YIN Jin-De, QING Du-An, LI Ling, YAN Pei-Guang
2024,43(3):295-301, DOI: 10.11972/j.issn.1001-9014.2024.03.001
Abstract:
This paper introduces a low-thickness sandwich waveguide structure comprising silicon nitride -sapphire -silicon nitride layers. By exploiting its dispersion wave radiation effect and mid-infrared phase matching condition， combined with the waveguide pulse transmission model， this study examines the impact of different physical sizes of the sandwich waveguide on the phase matching point and spectral broadening. Through numerical simulation， a supercontinuum spectrum ranging from 0.5 to 4 μm is generated， producing a farther mid-infrared dispersion wave at a -40 dB level. Moreover， this model provides an in-depth mechanism for nonlinear waveguide pulse transmission. Theoretical analysis reveals that modifying the physical size of the silicon nitride and sapphire interlayer and altering the phase-matching conditions can regulate the position of the dispersion wave across a broader wavelength range.
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XIAO Zheng-Qiong, DAI Hao-Guang, LIU Xin-Yang, CHEN Ping-Ping, ZHA Fang-Xing
2024,43(3):302-306, DOI: 10.11972/j.issn.1001-9014.2024.03.002
Abstract:
The cross-sectional scanning tunneling microscopy （XSTM） technique was used to study the cleaved surface of Hg0.72Cd0.28Te grown by molecular beam epitaxy. Scanning tunnel spectroscopy （STS）’s measurements show that the width of zero current plateau （the apparent tunneling gap） of current-voltage （I/V） spectra is about 130% larger than the practical band gap of the material， implying the existence of obvious tip-induced band bending （TIBB） effect with the measurement. Based on the 3D TIBB model， the STS data can however be interpreted and the calculated I/V spectra are in good agreement with the measurement. Nevertheless， certain deviation appears for those I/V data which were acquired with a large imaging bias. This is because the current TIBB model does not take into account the transport mechanism of the material itself， for which the band-to-band tunneling， trap assisted tunneling etc. could be non-negligible factors for the tunneling.
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Improved liquid phase epitaxy method for in-situ growth of HgCdTe with positive composition gradient
HUO Qin, HAN Hong-Qiang, ZHANG Cheng, JIAO Cui-Ling, WANG Reng, MAO Cheng-Ming, LU Ye, CHEN Xin-Tian, QIAO Hui, LI Xiang-Yang
2024,43(3):307-315, DOI: 10.11972/j.issn.1001-9014.2024.03.003
Abstract:
The influence of growth conditions of liquid phase epitaxy on the composition gradient of HgCdTe was studied， and the growth model of liquid phase epitaxy （LPE） of HgCdTe was established. HgCdTe with positive composition gradient was grown by slider liquid phase epitaxy by changing the mercury loss rate. The positive composition gradient structure of HgCdTe grown under the growth condition of specific mercury loss was confirmed by corrosion thinning spectrum and secondary ion mass spectrometry （SIMS）. The experimental results show that the HgCdTe with positive composition gradient had the similar surface morphology and infrared transmission spectrum curve to the traditional HgCdTe with negative composition gradient. It had high crystal quality， with a full width at half maximum （FWHM） of X-ray diffraction（XRD）double-crystal rocking curve of 28.8 arcsec.
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XING Yan-Hui, HE Wen-Xin, HAN Zi-Shuo, GUAN Bao-Lu, MA Hai-Xin, MA Xiao-Hui, HAN Jun, SHI Wen-Hua, ZHANG Bao-Shun, LYU Wei-Ming, ZENG Zhong-Ming
2024,43(3):316-323, DOI: 10.11972/j.issn.1001-9014.2024.03.004
Abstract:
The photogating effect based on the vertical structure of a two-dimensional material allows high-sensitivity and broad-spectrum photodetector. A high-sensitivity photodetector based on the vertical heterostructure of indium selenide （InSe）/molybdenum ditelluride （MoTe2） is reported， which exhibits excellent broad-spectrum detection capability from 365 to 965 nm. The top layer of InSe was used as the grating layer to regulate the channel current， and MoTe2 was used as the transmission layer. By combining the advantages of the two materials， the photodetector has a fast response time of 21.6 ms and achieves a maximum detectivity of 1.05 × 1013 Jones under 365 nm laser irradiation. Under the illumination of 965 nm， the detectivity still achieves the order of 109 Jones. In addition， the InSe/MoTe2 heterostructure exhibits an external quantum efficiency of 1.03 × 105 %， demonstrating strong photoelectric conversion capability.
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LU Xiao-Sen, WU Xu, WEI Xiao-Ke, WANG Jun-Jie, WANG Qi-Liang, JIN Zuan-Ming, PENG Yan
2024,43(3):324-330, DOI: 10.11972/j.issn.1001-9014.2024.03.005
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This study investigates an asymmetric tip design for a far-infrared metamaterial aimed at enhancing the Q factor and detection sensitivity. Employing the conventional double-split square ring resonator as a model， we conducted theoretical simulations to investigate the impact of different tip angles on the electric field distribution， resonance spectrum， and Q factor. The results show that the asymmetric tip increases the surface electric field of the resonator， decreases the full width at half maximum （FWHM） of the resonance peak， and increases the Q factor to over three times that of the conventional split ring. Our findings offer valuable insights for the development of highly sensitive far-infrared metamaterial sensors. Furthermore， we propose a straightforward and practical optimization approach to enhance the Q factor of conventional split ring metamaterials.
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FENG Rui-Ze, CAO Shu-Rui, FENG Zhi-Yu, ZHOU Fu-Gui, LIU Tong, SU Yong-Bo, JIN Zhi
2024,43(3):331-335, DOI: 10.11972/j.issn.1001-9014.2024.03.006
Abstract:
In this letter， an In0.53Ga0.47As/In0.52Al0.48As InP-based HEMT with fT > 400 GHz was designed and fabricated successfully. A narrow gate recess technology was used to optimize the parasitic resistances. The gate length is 54.4 nm， and the gate width is 2 × 50 μm. The maximum drain current IDS.max is 957 mA/mm， and the maximum transconductance gm.max is 1 265 mS/mm. The current gain cutoff frequency fT is as high as 441 GHz and the maximum oscillation frequency fmax reaches 299 GHz， even at a relatively small value of VDS = 0.7 V. The reported device can be applied to terahertz monolithic integrated amplifiers and other circuits.
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ZHANG Jia-Wen, JIN Jun-Da, SHI Sheng-Cai, LI Jing, GENG Wei, LYU Wei-Tao, LI Zhi, ZHI Qiang, PENG Zhao-Hang
2024,43(3):336-345, DOI: 10.11972/j.issn.1001-9014.2024.03.007
Abstract:
The homodyne mixing system is used to characterizing the performance of terahertz superconducting kinetic inductance detectors （KIDs）. However， homodyne mixing systems still have issues such as mixer imbalance， measurement system integration， and interference signals. The author designed a new single channel homodyne mixing hardware system and software algorithms to achieve integration of the measurement system， calibration of IQ-mixer imbalance， and performance characterization of KID； Furthermore， noise measurement of KIDs in VNA （vector network analyzer） CW mode is achieved； Finally， the method of hardware circuit design by dual channel homodyne mixing system based on autocorrelation algorithm effectively suppresses interference signals. It is worth noting that these research results are applied to characterize the performance of KIDs， which is important in the design of KIDs arrays.
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LI Xu, ZHANG Meng-Yuan, ZHAO Wen-Yue, ZUO Jian, ZHU Wei-Feng, LI Zhe, SHI Yu-Lei, ZHANG Cun-Lin
2024,43(3):346-355, DOI: 10.11972/j.issn.1001-9014.2024.03.008
Abstract:
Generally， the porosity of traditional Chinese medicine is measured by the destructive method of density measurement， but there is a lack of non-destructive quantification methods. As one important non-destructive method， terahertz radiation has been used to non-destructively extract the drugs'' time-domain and frequency-domain optical information. For direct compression traditional Chinese medicine tablets， the effective refractive index of various tablets was obtained by different methods of terahertz time-domain signal processing and frequency-domain signal processing. It was found that the effective refractive indices with either signal processing method show a good linear relationship with the porosities of the tablets. The porosity of Puerariae Lobatae Radix tablets was extracted and modeled by linear regression based on four effective medium theory models. The porosity regression model based on the effective refractive index by time-domain signal processing shows better performance on the model interpretation and cross-validation accuracy， with the best model of the Bruggeman model （RPD=11.3325）. It provides support for the process optimization of porous powder preparation of traditional Chinese medicine.
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LI Hong-Yi, TAN Zhi-Yong, WAN Wen-Jian, CAO Jun-Cheng
2024,43(3):356-360, DOI: 10.11972/j.issn.1001-9014.2024.03.009
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A homodyne detection system to acquire the thickness of silicon wafers is constructed and described. By harnessing the relationship between the transmission phase change of a 4.3-THz light beam and the incident angle controlled by a mechanical rotating stage， the thickness value of sample can be precisely deduced using the standard residual error method. The results indicate that the fitted thickness of the sample differs by only 2.5~3 μm from more accurate results measured by optical microscopes， achieving terahertz non-destructive thickness measurement with micron level accuracy. The experiment validates the effectiveness of terahertz quantum-cascade laser in non-contact and nondestructive measurement.
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XU Zhen, XU De-Gang, LIU Long-Hai, LI Ji-Ning, ZHANG Jia-Xin, WANG Tan, REN Xiang, QIAO Xiu-Ming, JIANG Chen
2024,43(3):361-370, DOI: 10.11972/j.issn.1001-9014.2024.03.010
Abstract:
The current main detection methods for packaging chip defects with small size， dense wiring， and high integration have drawbacks such as low accuracy and long cycle time. To compensate for the shortcomings of traditional detection methods， this study combines terahertz technology with time-domain reflection technology to explore the feasibility of detecting metal wire defects on chips. Firstly， different proportions of convex defects and concave defects were processed on metal microstrip lines of different widths to simulate incomplete opening/short circuits of metal wires in integrated chips. The time-domain reflection signals were collected using a terahertz time-domain reflectometer. Then， qualitative analysis was conducted on different defect degrees and types based on the corresponding time of time-domain reflection pulses， and the defect positions of the metal wires on the chip were accurately calculated. Finally， the finite element analysis method was used to simulate and analyze the metal wires with defects on the silicon substrate， which showed perfect consistency with the experimental results. This research shows that the combined terahertz technology with time-domain reflection technology can achieve the diagnosis and detection of metal wire defects on chips， providing an empirical reference for defect detection in integrated chips.
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2024,43(3):371-376, DOI: 10.11972/j.issn.1001-9014.2024.03.011
Abstract:
Metasurface provide a new platform for studying planar and ultrathin optical components. The traditional geometric-phase-based metalens are limited to the polarization locking， which inevitably hinders its function in multiplexing of multiple functions. Herein， an approach based on the geometric phase is proposed to realize polarization decoupling of metalens. This method can be applied to design metalens that enables functionalities of polarization switchable multi-functions（focusing and vortex beam etc...） multiplexing in the longitudinal direction or both the longitudinal and transverse directions. The results provide a new avenue for multifunctional integrated planar components.
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A simplified parameterization scheme of mid-infrared radiative transfer for satellite remote sensing
YAO Qian, XU Hua, FAN Cheng, LI Li, WANG Si-Heng, ZHENG Yang, XU Wen-Bin, HOU Wei-Zhen, XU Jing-Hai, ZHUANG Qi-Feng, ZHOU Peng, ZHANG Hao, CHEN Zhen-Ting, LI Zheng-Qiang
2024,43(3):377-392, DOI: 10.11972/j.issn.1001-9014.2024.03.012
Abstract:
As the connecting spectral band of visible-near infrared and thermal infrared， mid-infrared （MIR） combines the reflective characteristics of short-wave radiation and the emissive characteristics of long-wave radiation， which is of great importance for application scenarios such as temperature detection and target identification. At present， the radiative transfer （RT） calculation of the MIR spectrum still faces the problem of many input background parameters which are not easy to obtain. Based on this， a simplified parameterization scheme of MIR RT for satellite remote sensing is proposed. Using the MODTRAN model （MM）， the background surface and atmospheric parameters involved in the MIR daytime RT process were quantitatively simulated and analyzed to obtain the key parameters affecting RT， from which an MM-based parameter simplified scheme （SS） was developed. The total radiance calculated by SS and MM is compared and validated at the center wavelength of 6 MIR channels of MODIS， and the RMSE is less than 0.004399 with high accuracy. The SS only relies on surface temperature， surface emissivity， atmospheric profile type， water vapor and cloud optical thickness， and does not require input of aerosol， CO2 and O3 data. Compared with the MM， the SS reduces the input parameters from 8 categories to 5 categories， and the calculation time efficiency increases by 9.02%. With limited computational resources， the SS proposed in this paper can provide support for the application areas such as fast processing of MIR images and remote sensing simulation of large scenes.
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YANG Jian, MA Yue, YU Wen-Bo, LI Shao-Hui, YU Jing, WANG Qian-Yin, LI Song
2024,43(3):393-398, DOI: 10.11972/j.issn.1001-9014.2024.03.013
Abstract:
With the advantage of high sensitivity and high repetition rate， spaceborne photon counting Lidar has shown great application in ocean areas. The photon counting detector can not only respond to the weak echo signal， but is also susceptible to solar radiation. Due to the great impact of background noise on the performance of Lidar systems， as well as the impact on the data volume， accurate estimation of noise level is crucial in the design of satellite Lidar systems. A noise model of oceanic spaceborne photon counting Lidar was proposed that considers the contribution of the atmosphere， water surface， and water column. By inputting the system parameters of the new generation photon counting Lidar ATLAS and the environmental parameters， the MAPEs （mean absolute percentage errors） between estimated noise and the ATLAS measured noise are within 15%， which confirms the effectiveness of the noise model.
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ZHANG Si-Qi, CHEN Peng, ZHANG Zhen-Hua, PAN De-Lu
2024,43(3):399-407, DOI: 10.11972/j.issn.1001-9014.2024.03.014
Abstract:
The spaceborne light detection and ranging （LiDAR）， as a novel active remote sensing technology， offers possibilities for global diurnal research. In this study， global sea surface chlorophyll-a （Chla） concentrations were inverted using satellite data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations （CALIPSO）. A feedforward neural network model based on LiDAR data （FNN-LID） was developed to reconstruct a long-term diurnal dataset of sea surface pCO2 in the Arctic Ocean. Subsequently， verification and analysis were conducted on the polar sea surface Chla concentrations and sea surface pCO2 based on active remote sensing. The results demonstrated that the inversion products generated by this algorithm exhibit high data quality and exhibit favorable consistency with both other passive remote sensing products and buoy observations. Moreover， these products effectively fill data gaps during polar winters. Along the Arctic Ocean， margin seas significantly influenced by terrestrial sources consistently display high sea surface Chla concentrations. The spatial distribution of sea surface pCO2 in the Arctic Ocean manifests meridional variations， with marked seasonal fluctuations， even higher than 80 μatm. Over the past two decades， the Arctic Ocean has consistently acted as a carbon dioxide sink， while areas with substantial sea ice decline such as the East Siberian Sea and Kara Sea exhibit pronounced increases in sea surface pCO2.
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YU Tian-Yan, QIN Yang, JIANG Lin, DUAN Wei-Bo, LIU Ding-Quan
2024,43(3):408-414, DOI: 10.11972/j.issn.1001-9014.2024.03.015
Abstract:
This paper describes the design and fabrication of one kind of dichroic beam-splitter that operates in an ultra-broadband spectral range from visible to longwave infrared regions simultaneously. The use of metal-dielectric coatings makes it implement structures that transmit the visible/near infrared radiation from 0.4 to 1.05 μm and reflect infrared radiation from 1.36 to 13 μm. At the same time， the structures are designed to obtain a low linear polarization sensitivity （LPS） in the visible/near infrared region. The transmission of visible/near infrared region is more than 85% and the average reflection of infrared region is more than 90%. The LPS of the region 0.4-1.05 μm is less than 4%.
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2024,43(3):415-422, DOI: 10.11972/j.issn.1001-9014.2024.03.016
Abstract:
A dual-channel macroscopic imaging system has been developed based on optical methods， which can simultaneously capture the visible light and near-infrared second window （NIR-II） fluorescence. It could provide high-quality bright-field real-time images with the NIR-II fluorescence information， addressing the significant disparity issue between fluorescence and bright-field images in conventional NIR-II macroscopic imaging systems. In the experiment， the anti-scattering capability and imaging performance of NIR-II fluorescence signals of indocyanine green （ICG） were tested using different thicknesses of adipose tissues in the band of 1 100-1 700 nm and 1 300-1 700 nm respectively. Subsequently， the dual-channel macroscopic imaging system was used to obtain lymph node images of mouse and rat models， simulating the lymph node resection surgery and mimicking the process of abdominal lymph node clearance. Finally， different thicknesses of biological adipose tissues were added to the rat model to simulate the presence of adipose tissues covering the lymph nodes during actual surgery， and the penetration capability of the dual-channel system was observed. The visible and near-infrared second window dual-channel fluorescence imaging system provided the intuitive visual information to the operator， reducing surgery time and improving the patient prognosis， and held great potential for application in clinical surgical navigation.
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2024,43(3):423-436, DOI: 10.11972/j.issn.1001-9014.2024.03.017
Abstract:
Image impulse noise removal is essential for obtaining high-quality images. A novel pixel gradients-based adaptive iterative median filter is proposed to remove image impulse noise by utilizing the principles of thermal infrared camera imaging. Firstly， the maximum pixel gradient of the original image is computed based on the camera''s modulation transfer function （MTF）， and a corresponding set of pixel gradients is established. Subsequently， the gradient weight root-mean-square error （GWRMSE） set of the original image and the corresponding pixel gradient filtered image is computed， and the optimal pixel gradient is determined as the one corresponding to the maximum value of Gaussian distribution of the GWRMSE set. Finally， the adaptive window size and number of iterations for the proposed filter are determined according to the density and complexity of the impulse noise in the image. Extensive experimental results demonstrate that the proposed filter exhibits excellent robustness in removing 8-bit and 16-bit single-channel impulse noise images. In comparison with other state-of-the-art methods， the proposed method can remove low-density random-valued impulse noise （RVIN） and salt-and-pepper noise （SAPN） in real thermal infrared camera-acquired images in real-time while preserving more than 99.5% of original pixels during the noise removal process. Additionally， for high-density SAPN removal， the proposed method achieves competitive results， demonstrating better peak signal-to-noise ratio （PSNR） and structural similarity index （SSIM） in comparison with filtering methods of faster running time and faster execution time in comparison with denoising methods of superior PSNR and SSIM. Moreover， it can recover meaningful image details even for images severely damaged by extreme SAPN （99%）.
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Volume 43,2024 Issue 3
Infrared Materials and Devices
Terahertz and Millimeter Wave Technology
Remote Sensing Technology and Application
Infrared Photoelectric Technology and Application
Image Processing and Software Simulation
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LU Dun, FU Wen-Jie, MIKHAIL Glyavin, TANG Xiang-Wei, HU Min, LIU Sheng-Gang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In general， all known applications of high-power microwaves directly use energy to interact with matter. In recent years， with the development of powerful millimeter-wave radiation sources， microwave technology has gradually shifted towards the millimeter-wave frequency band. Due to the wavelength of radiation， millimeter waves have several unique characteristics， which allow for both the active development of existing technologies and the creation of new ones that require high power or radiation energy. This article provides an overview of research on the application of millimeter waves to solve problems in physics， material science， biomedicine， and others， including heating and diagnostics of thermonuclear plasma， processing and analysis of materials， biological effects， etc. The main difficulties arising in the implementation of the described tasks are presented， and the future development is also prospected.
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Zhang Jing, YANG Zhi, ZHENG Liming, ZHU Xiaojuan, WANG Ping, YANG Lin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
This paper discusses the influence of Sb/In ratio on the transport properties and crystal quality of the 200 nm InAsxSb1-x thin film. The Sb content of InAsxSb1-x thin film in all samples was verified by HRXRD of the symmetrical 004 reflections and asymmetrical 115 reflections. The calculation results show that the Sb component was 0.6 in the InAsxSb1-x thin film grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3, which has the highest electron mobility (28560 cm2/V·s) at 300 K. At the same time, the influence of V/III ratio on the transport properties and crystal quality of Al0.2In0.8Sb/InAsxSb1-x quantum well heterostructures also has been investigated. As a result, the Al0.2In0.8Sb/InAs0.4Sb0.6 quantum well heterostructure with a channel thickness of 30 nm grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3 has a maximum electron mobility of 28300 cm2/V·s and a minimum RMS roughness of 0.68 nm. Through optimizing the growth conditions, our samples have higher electron mobility and smoother surface morphology.
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GUO Yuan-Sen, CHEN Li-Gang, YAN Shi-Han, FU Ying, QIU Fu-Cheng, YANG Zhong-Bo, ZHANG Ming-Kun, TANG Ming-Jie, WANG Hua-Bin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Terahertz （THz） technology is undergoing a rapid development in biomedical applications. Researchers have made a series of important achievements in the study of biological samples on various levels such as biomolecules， cells， tissues， and individual organisms， which provide new insights and innovative approaches for biological research and biomedical diagnosis. In this review， the progress of applying THz technology in biomedical studies has been summarized， including three key aspects， namely， spectroscopic detection， imaging， and biological effects. The challenges encountered in THz biomedical applications have been discussed， and the future development directions have also been envisioned.
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ZHAN Jia, ZHA Fang-Xing, GU Yi
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Photoreflectance （PR） has been widely used for the characterization of various semiconductors as well as their surface and interface properties due to its non-destructive and high sensitivity virtues. From the viewpoint of the employment of monochromator， the experimental setup may be classified into front and backside （or dark and bright） configurations， which were applied to characterize the heterostructure of InP/In0.52Ga0.48As/InP grown by molecular beam epitaxy. It reveals that the front configuration well separates the luminescence from the modulation signal while the backside configuration benefits the extraction of weak modulation signals with the employment of high excitation power. Based on the backside configuration， we also observed a below band-gap excitation phenomenon， i.e. that the modulation signal of InP exhibits under the excitation of energetically low modulation light （1064 nm laser）. The result demonstrates that the backside configuration may be employed as a contactless electro-modulation technique for the characterization of wide band gap semiconductor heterostructures.
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Wan Jing, Yu Tingjie, Chen Jiansong, Zhou Rui, Wan Hongdan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Variable optical attenuator （VOA） arrays can be widely applied in optical communication and optoelectronic systems， but few VOA arrays are reported. Here a liquid-stop based microfluidic VOA array is proposed. It uses a spiral orbit to achieve different degrees of synchronous energy attenuation of multiple beams， or uses an annular orbit to achieve a same degree of synchronous energy attenuations， where the clear aperture of liquid stop is regulated by the electrowetting-on-dielectric effect. It has a compact structure， small volume， simple operation and low cost. Meanwhile， the attenuation ratio of beams can be flexibly adjusted to achieve the power equalization. The research results indicate that the VOA array has a wide attenuation range （0-100% attenuation） and very small insertion loss （0.26 dB） over general VOA arrays. The response time is 0.1 ms， and it is insensitive to the polarization. It can also act as an optical switch array. The proposed VOA array demonstrates the potential of integration and high performance， and it can provide a cost-effective way for applications.
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HUI Zhan-Qiang, LI Jia-ying, LI Tian-Tian, HAN Dong-Dong, GONG Jia-Min
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Optical coherence tomography （OCT） technology has the advantages of non-invasive， high-resolution， and real-time imaging， which is widely used in various fields such as biomedicine， material science and infrared sensing. In this paper， a ridge suspended optical waveguide based on silicon nitride （Si3N4） is proposed. The structural parameters of the designed waveguide were optimized by using finite difference time domain （FDTD） method. The characteristics of the supercontinuum spectrum generated in the optimized waveguide were investigated The simulation results show that for the optimized optical waveguide structure with ridge width of 750nm， ridge height of 700nm， plate thickness of 200nm， and upper layer height of 150nm， when a pump light with wavelength of 1.3μm， peak power of 2kW and pulse width of 50fs was injected into the waveguide， a broadband supercontinuum spectrum with wavelength covering the visible to the mid-infrared region （703~4014nm） can be generated. This work plays an important role in promoting the application of on-chip integrated broadband light source in biomedical imaging and related fields.
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MA Qiu-Jing, DUAN Wei-Bo, YU Tian-Yan, LI Da-Qi, YU De-Ming, LIU Bao-Jian, ZHUANG Qiu-Hui, LIU Ding-Quan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The effects of calcium fluoride （CaF2） doping on the optical and physical and chemical properties of Ytterbium fluoride （YbF3） materials were studied. Pure YbF3 thin films and YbF3 thin films doped with different proportions of CaF2 were deposited by electron beam and thermal evaporation， respectively. The characteristics of single layer were measured by spectrometer， stress measurement system， X-ray Diffraction （XRD）， Atomic Force Microscope （AFM） and other measuring devices. The optical constants were fitted by the classical Lorentz oscillator model. The results show that the single-layer film with better optical and physical and chemical properties is obtained by electron beam deposition， in the condition of 1% CaF2 doping. A long-wave infrared anti-reflection multi-layer sample was designed and fabricated and its spectrum and reliability test were carried out. The results show that its transmittance in the long-wave infrared region is as high as 99%， and the reliability meets the requirements of space application.
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JIANG Lu-Han, MA Han-Song, ZHANG Qin-Yi, TIAN Peng, HAN Yang, WANG Ming-Xu, TAN Jing-Wen, XU Si-Cong, ZHANG Bing, Rehim Uddim, WEI Yi, YANG Xiong-Wei, LI Wei-Ping, YU Jian-Jun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
To meet the high-speed and high-capacity demands of communication, a 300GHz electronic wireless transmission system for terahertz frequencies is proposed, which incorporates Probability Shaping (PS), Discrete Multi-tone Modulation (DMT) and DFT-Spread (DFT-S) techniques. PS increases the Euclidean distance between constellation points, thereby enhancing the receiver sensitivity. In the system at most 55% bit error rate is decreased, enabling to extend transmission range. DFT-S technique reduces 1.68 dB peak-to-average power ratio of Orthogonal Frequency Division Multiplexing (OFDM) signals in the system, thus improving their resistance to nonlinear effects. By integrating these advanced digital signal processing techniques, 12GBaud PS-16QAM OFDM-DMT signals and 10GBaud PS-64QAM DFT-S-OFDM-DMT signals were successfully implemented in 1 m wireless transmission. Finally, the performance advantages of these digital signal processing techniques were compared.
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Li Yunpeng, Luo Jiacheng, Ji Ruonan, Xie Maobin, Cui Wennan, Wang Shaowei, Liu Feng, Lu Wei
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Metasurfaces in the long wave infrared （LWIR） spectrum hold great potential for applications in thermal imaging， atmospheric remote sensing， and target identification， among others. In this study， we designed and experimentally demonstrated a 4 mm size， all-silicon metasurface metalens with large depth of focus operational across a broadband range from 9 μm to 11.5 μm. The experimental results confirm effective focusing and imaging capabilities of the metalens in LWIR region， thus paving the way for practical LWIR applications of metalens technology.
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LIU Mao-Fan, YU Chun-Lei, MA Ying-Jie, YU Yi-Zhen, YANG Bo, TIAN Yu, BAO Peng-Fei, CAO Jia-Sheng, LIU Yi, LI Xue
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The development of InGaAs/InP single-photon avalanche photodiodes （SPADs） necessitates the utilization of a two-element diffusion technique to achieve accurate manipulation of the multiplication width and the distribution of its electric field. Regarding the issue of accurately predicting the depth of diffusion in InGaAs/InP SPAD， simulation analysis and device development were carried out， focusing on the dual diffusion behavior of zinc atoms. A formula of
to quantitatively predict the diffusion depth is obtained by fitting the simulated twice-diffusion depths based on a two-dimensional （2D） model. The 2D impurity morphologies and the one-dimensional impurity profiles for the dual-diffused region are characterized by using scanning electron microscopy and secondary ion mass spectrometry as a function of the diffusion depth， respectively. InGaAs/InP SPAD devices with different dual-diffusion conditions are also fabricated， which show breakdown behaviors well consistent with the simulated results under the same junction geometries. The dark count rate （DCR） of the device decreased as the multiplication width increased， as indicated by the results. DCRs of 2 106， 1 105， 4 104， and 2 104 were achieved at temperatures of 300K， 273K， 263K， and 253K， respectively， with a bias voltage of 3V， when the multiplication width was 1.5 μm. These results demonstrate an effective prediction route for accurately controlling the dual-diffused zinc junction geometry in InP-based planar device processing. -
FU Peng, HE Dao-Gang, LIU Jun, WANG Yue-Ming
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction. In satellite laser communication systems， the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation. However， there are strong non-uniformity and blind pixels in the short-wave infrared image， which makes the image distorted and leads to the decrease of spot centroid positioning accuracy. Therefore， the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance. A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two， further model-based localization error simulations are performed， and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector. The experimental results show that the non-uniformity of the corrected image is reduced from 7% to 0.6%， the blind pixels rejection rate reaches 100%， the frame rate can be up to 2000 Hz， and the spot centroid localization accuracy is as high as 0.1 pixel point， which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.
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WANG Zhong, SUN Shengli, CHEN Rui, MA Yijun, XU Wenjun, ZHANG Yafeng
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Through sufficient investigation and summary， the development trend and representative work of Metaverse and related technologies in the aerospace field since the 1960s have been sorted out， and it is pointed out that multi-satellite networking， digitalization and virtualization will become important development trends of aerospace science and technology. Hence， a new concept called “Aerospace Metaverse” has been proposed. Based on this concept， the fundamentals of mathematics and physics have been analyzed. Necessry technologies to build Aerospace Metaverse such as digital twins of aerospace and wide domain ultra high speed intelligent perceptionhave been proposed， and their implementation approaches are elaborated. Furthermore， combining with the vigorous development of aerospace technology， scenarios that can be first put into use have been predicted. Several existing difficulties in building Aerospace Metaverse and corresponding solutions have been proposed， providing new ideas for the development of aerospace technology. Finally， an outlook has been made on the future development of Aerospace Metaverse
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YANG Yu, LONG Ming-liang, ZHANG Hai-feng, ZHANG Xiao-xiang, HUANG Xing-min, DING Jie, LI Pu, DENG Hua-rong, ZHANG Zhong-ping
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
High-precision space debris measurements can provide more accurate real-time information on debris targets and enhance the effectiveness of satellite avoidance warnings for space debris. Through the modification of the 1.2 m aperture quantum communication telescope (altitude 3200 m) in Qinghai Province, the satellite laser ranging (SLR) and space debris laser ranging (DLR) experiments were carried out by using a single pulse energy of 1.2 mJ and a repetition rate of 1 kHz picosecond laser, in which the detection range of cooperative satellites has been extended from Low Earth Orbit to Geosynchronous Eearth Orbit, and the ranging accuracy was better than 2 cm. The maximum distance of space debris target measurement is 1620.5 km, the radar cross section (RCS) is 2.41 m2, and the ranging accuracy reaches 10.64 cm.A single laser system has been realized, which can not only carry out centimeter-level high-precision ranging of cooperative targets, but also realize space debris observation.. This is the first time in the world to use high repetition frequency and low power laser ranging system to achieve high precision measurement of space debris targets, reflecting the advantages of picosecond laser and high-altitude large-aperture telescope measurement, providing reference for developing space target laser ranging in western China, and providing an effective way for space debris laser ranging system site selection and space debris monitoring capability enhancement.
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DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Remote sensing image scene classification aims to automatically assign a semantic label to each remote sensing image according to its content， and has become one of the hot topics in the field of remote sensing image processing.Methods based on convolutional neural networks （CNNs） and methods based on self-attention mechanism are two mainstream methods in remote sensing image scene classification. However， the former is less effective in exploring long-range contextual information， and the latter has limitations in learning local information and has a large number of parameters and calculations. In order to address these issues， a lightweight method based on knowledge distillation is proposed to solve the problem of scene classification for remote sensing images. The proposed method uses Swin Transformer and lightweight CNNs as the teacher model and the student models， respectively， and integrates the advantages of the two kinds of models by means of knowledge distillation. Furthermore， a novel distillation loss function is proposed to enable the student models to focus on both inter- and intra-class potential information of remote sensing images simultaneously. The experimental results on two large-scale remote sensing image datasets demonstrate that the proposed method not only achieves high classification accuracy compared to existing methods but also has a significantly reduced number of parameters and calculations.
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LI Yi-Qi, SUN Xiao-Bing, HUANG Hong-Lian, LIU Xiao, TI Ru-Fang, ZHENG Xiao-Bing, YU Hai-Xiao, WEI Yi-Chen, WANG Yu-Xuan, WANG Yu-Yao
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Variations of extinction and microphysical properties in the upper haze of Venus will affect the chemistry and radiative balance of the Venus atmosphere. To study their spatial and temporal distribution， solar occultation data from Venus Express SPICAV SOIR instruments between 2006 and 2013 were analyzed. The absorption effects of the Venus" middle and upper atmosphere were first removed using MODTRAN modeling. The extinction profiles of the upper haze between 67～92 km were then retrieved using the onion-peeling method. The results show that： 1） The extinction coefficient of the upper haze generally decreased with increasing altitude. Large variations existed between different regions. The extinction at low latitudes increased sharply early in the mission and the average extinction coefficient of haze changes slightly between day and night. The vertical optical depth of the haze layer was on the order of 10-2. 2） The number density of the upper haze decreased with increasing altitude. From south to north pole， the number density first increased and then decreased. 3） Cloud top altitude is higher in low-latitude regions at 82.7 ± 5.8 km， whereas in polar regions cloud top altitude is lower with the the northern polar region at 73.3 ± 2.4 km， and the southern polar region at 79.5 ± 3.5 km. The average scale height of the upper haze layer in the northern polar region is 4.0 ± 0.9 km.
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CHEN Chen, TONG Xiao-Hua, LIU Shi-Jie, YE Zhen, WU Hao, ZHANG Han
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevitably affected by the orbiter attitude jitter. Therefore, it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching. In this work, an imaging simulation method considering the attitude jitter is presented. The impact analysis of different attitude jitter on terrain undulation is conducted by simulating jitter at three attitude angles, respectively. The proposed simulation method is based on the rigorous sensor model, using the lunar digital elevation model (DEM) and orthoimage as reference data. The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter. Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit. Experimental analyses were conducted by the DEM with the simulated stereo image. The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping. The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison.
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HOU Zhi-Jin, Chen Yan, Wang Xu-Dong, Wang Jian-Lu, Chu Jun-Hao
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Silicon （Si） diffraction microlens arrays are usually used to integrating with infrared focal plane arrays （IRFPAs） to improve their performance. The errors of lithography are unavoidable in the process of the Si diffraction microlens arrays preparation in the conventional engraving method. It has a serious impact on its performance and subsequent applications. In response to the problem of errors of Si diffraction microlens arrays in the conventional method， a novel self-alignment method for high precision Si diffraction microlens arrays preparation is proposed. The accuracy of the Si diffractive microlens arrays preparation is determined by the accuracy of the first lithography mask in the novel self-alignment method. In the subsequent etching， the etched area will be protected by the mask layer and the sacrifice layer or the protective layer. The unprotection area is carved to effectively block the non-etching areas， accurately etch the etching area required， and solve the problem of errors. The high precision Si diffraction microlens arrays is obtained by the novel self-alignment method and the diffraction efficiency could reach 92.6 %. After integrating with IRFPAs， the average blackbody responsity increased by 8.3 %， and the average blackbody detectivity increased by 10.3 %. It indicates that the Si diffraction microlens arrays can improve the filling factor and reduce crosstalk of IRFPAs through convergence， thereby improving the performance of the IRFPAs. The results are of great reference significance for improving their performance through optimizing the preparation level of micro nano devices.
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Simulation analysis of radiation terahertz wave characteristics of photoconductive antenna materials
HOU Lei, WU Xiao-Bo, YANG Lei, SHI Wei, HANG Yu-Hua
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The photoconductive antenna is a kind of widely used broadband terahertz （THz） radiation source in THz time-domain spectroscopy systems， and the substrate material of the antenna is crucial for the characteristics of generated THz wave. The widely used photoconductive antenna material is the second-generation semiconductor of GaAs， while the third-generation semiconductor has a larger band gap， which is more advantageous for improving the power of THz wave from photoconductive antenna. In this work， the current surge model of large-aperture photoconductive antennas was used to simulate the characteristics of THz waves radiated by the photoconductive antenna made from commonly used SI-GaAs and LT-GaAs， and the third-generation semiconductors （ZnSe， GaN， SiC） that are expected to be used in the future for photoconductive antennas. The results show that under the same bias electric field and their respective highest pump laser flux， LT-GaAs antenna generates THz waves with the highest amplitude and widest frequency. The photoconductive antenna made by the third-generation semiconductor materials can withstand higher bias electric fields， and the intensity of radiated THz waves is much greater than that from GaAs antennas under their respective maximum bias electrical fields. This work provides theoretical guidance for the development of new third-generation semiconductor photoconductive antennas.
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LIU Sheng, SHEN Yuan-Jie, HOU Guang-Ning, ZHA Zhi-Peng, ZHU Yi-Zhen, YU Shuo-Ying, ZHANG Qing-Tian, ZHAO Qiang, LIU Shao-Hua, JING Cheng-Bin, CHU Jun-Hao
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The performance of ABS/Ag-coated terahertz hollow waveguide （HWG） was improved through plasma treatment of the ABS structural tube. The adhesion of the silver （Ag） film to the ABS tube was enhanced from level 5 to level 2 after plasma treatment. The 4.2 mm bore waveguide sample treated with plasma has a more uniform and denser silver film than the untreated sample， which contributes to the reduction of transmission losses from 0.72 dB/m to 0.70 dB/m at 0.3 THz and 1.47 dB/m to 1.44 dB/m at 0.1 THz， respectively. After 200 hours of hydrothermal aging and 16 cycles of high and low temperature cycling testing， the straight loss of the HWG sample treated with plasma increased by less than 0.1 dB/m， while the untreated sample underwent an increase of more than 1.0 dB/m. The results indicate that the ABS/Ag-coated HWG fabricated by plasma treatment has lower loss， higher reliability and better anti-aging performance compared with the untreated sample. It can be potentially used for establishment of next-generation communication， sensing， and THz imaging systems.
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ZHANG Shuang, WANG Lu, WANG Wen-Qing
DOI:
Abstract:
A modified multiple-component scattering power decomposition for analyzing polarimetric synthetic aperture radar （PolSAR） data is proposed. The modified decomposition involves two distinct steps. Firstly， eigenvectors of the coherency matrix are used to modify the scattering models. Secondly， the entropy and anisotropy of targets are used to improve the volume scattering power. With the guarantee of high double-bounce scattering power in the urban areas， the proposed algorithm effectively improves the volume scattering power of vegetation areas. The efficacy of the modified multiple-component scattering power decomposition is validated using actual AIRSAR PolSAR data. The scattering power obtained through decomposing the original coherency matrix and the coherency matrix after orientation angle compensation is compared with three algorithms. Results from the experiment demonstrate that the proposed decomposition yields more effective scattering power for different PolSAR data sets.
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CHEN Ze-Ji, HUANG You-Wen, PU En-Xiang, XIAO Hui-Shan, XU Shi-Chun, QIN Qiang, KONG Jin-Cheng
DOI:
Abstract:
A medium wave （MW） 640×512 （25 μm） Mercury Cadmium Telluride （HgCdTe） polarimetric focal plane array （FPA） was demonstrated. The micro-polarizer array （MPA） has been carefully designed in terms of line grating structure optimization and crosstalk suppression. A monolithic fabrication process with low damage was explored， which was verified to be compatible well with HgCdTe devices. After monolithic integration of MPA， NETD < 9.5 mK was still maintained. Furthermore， to figure out the underlying mechanism that dominated the extinction ratio （ER）， specialized MPA layouts were designed， and the crosstalk was experimentally validated as the major source that impacted ER. By expanding opaque regions at pixel edges to 4 μm， crosstalk rates from adjacent pixels could be effectively reduced to approximately 2%， and promising ERs ranging from 17.32 to 27.41 were implemented.
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MA Yuan, LIN Yu-Zhe, WAN Chen-Yang, WANG Zi-Xian, ZHOU Xu-Yan, ZHANG Jin-Chuan, LIU Feng-Qi, ZHENG Wan-Hua
DOI:
Abstract:
We report on the performance improvement of long-wave infrared quantum cascade lasers （LWIR QCLs） by studying and optimizing the anti-reflection （AR） optical facet coating. Compared to the Al2O3 AR coating， the Y2O3 AR coating exhibits higher catastrophic optical mirror damage （COMD） level， and the optical facet coatings of both material systems have no beam steering effect. A 3-mm-long， 9.5-μm-wide buried-heterostructure （BH） LWIR QCL of λ ~ 8.5 μm with Y2O3 metallic high-reflection （HR） and AR of ~ 0.2 % reflectivity coating demonstrates a maximum pulsed peak power of 2.19 W at 298 K， which is 149% higher than that of the uncoated device. For continuous-wave （CW） operation， by optimizing the reflectivity of the Y2O3 AR coating， the maximum output power reaches 0.73 W， which is 91% higher than that of the uncoated device.
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WANG Zhen, LI Li-Guang, ZHAO Bai-Qing, LI Jia-Geng, HAN Qin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
To address the spatial constraints in unmanned aerial vehicle target detection systems， a scheme for a multi-beam scanning passive Q-switched microchip array solid-state laser is proposed. This system utilizes a six-core semiconductor laser array to compactly pump a strip-shaped Nd：YAG/Cr4+：YAG bonded crystal. At a pumping power of 1.6 W per path， it generates six output laser beams with a wavelength of 1 064.4 nm， pulse width of 2.4 ns， beam quality of 1.39， peak power of 3.75 kW， and a repetition frequency up to 22 kHz. The entire system"s volume is only 2 cm×2 cm ×1.5 cm， and achieves simultaneous output of six laser paths. The study investigated the impact mechanism of the initial transmittance of the Q-switching crystal and the reflectivity of the output mirror on the laser pulse repetition frequency and peak power， with a particular focus on the uniformity of the laser output from the pump source cores. The feasibility of using a single laser-bonded crystal to produce multiple narrow pulse laser beams in the nanosecond range was experimentally verified. The research results demonstrate the miniaturized structure"s ability to achieve multi-beam emission from a passive Q-switched solid-state laser， providing insights for the miniaturization and integration of laser sources in detection systems.
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WU Jia-Hao, QIAO Hui, LI Xiang-Yang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A method for selecting parameters in HgCdTe crystals has been proposed， utilizing Principal Component Analysis （PCA） and clustering methods， with the establishment of a data model for screening the parameters of HgCdTe crystals. Within the model， the initial crystal data undergoes a cleaning and analysis process. PCA is employed for dimensionality reduction， and the Density-Based Spatial Clustering of Applications with Noise （DBSCAN） algorithm is used to identify the densest regions within the crystal data. Furthermore， the high-performance chip data， obtained after post-processing， is utilized to fit boundary ellipses for high-quality HgCdTe crystal parameters. These ellipses act as criteria for identifying high-quality crystals. The model is capable of generating crystal ratings based on input electrical and optical parameters with a coverage rate exceeding 90%.
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DOI:
Abstract:
Infrared small target detection is a common task in infrared image processing. Under limited computational resources. Traditional methods for infrared small target detection face a trade-off between the detection rate and the accuracy. A fast infrared small target detection method tailored for resource-constrained conditions is proposed for the YOLOv5s model. This method introduces an additional small target detection head and replaces the original Intersection over Union （IoU） metric with Normalized Wasserstein Distance （NWD）， while considering both the detection accuracy and the detection speed of infrared small targets. Experimental results demonstrate that the proposed algorithm achieves a maximum effective detection speed of 95 FPS on a 15 W TPU， while reaching a maximum effective detection accuracy of 91.9 AP@0.5， effectively improving the efficiency of infrared small target detection under resource-constrained conditions.
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ZHANG Jian, CHANG Chao, LI Hong-Fu, SHI Yu-Na, YIN Han-Xiang, LI Yan-Hui, YUE Biao, WANG Hai-Peng, YAN Chang-Shan, DAI Xin-Ran, DENG Gong-Rong, KONG Jin-Cheng, ZHAO Peng, ZHAO Jun
DOI:
Abstract:
The lattice-matched XBn structures of InAsSb， grown on GaSb substrates， exhibit high crystal quality， and can achieve extremely low dark currents at high operating temperatures （HOT）. Its superior performance is attributed to the unipolar barrier， which blocks the majority carriers while allowing unhindered hole transport. To further explore the energy band and carrier transport mechanisms of the XBn unipolar barrier structure， this paper systematically investigates the influence of doping on the dark current， photocurrent， and tunneling characteristics of InAsSb photodetectors in the PBn structure. Three high-quality InAsSb samples with unintentionally doped absorption layers （AL） were prepared， with varying p-type doping concentrations in the GaSb contact layer （CL） and the AlAsSb barrier layer （BL）. As the p-type doping concentration in the CL increased， the device’s turn-on bias voltage also increased， and p-type doping in the BL led to tunneling occurring at lower bias voltages. For the sample with UID BL， which exhibited an extremely low dark current of 5×10-6 A/cm2. The photocurrent characteristics were well-fitted using the back-to-back diode model， revealing the presence of two opposing space charge regions on either side of the BL.
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PENG Hong-Ling, WEI Jia-Qi, SONG Chun-Xu, WANG Tian-Cai, CAO Peng, DENG Jie, CHEN Jian, ZHUANG Qian-Dong, ZHENG Wan-Hua
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Based on the current application requirements for wideband response photodetectors， we designed a novel silicon avalanche photodetector （Si APD） with high response in a broad spectral range of 250 -1 100 nm and it could achieve efficient detection of ultraviolet， visible and near-infrared light without splicing. The enhancement of silicon on ultraviolet and infrared bands was separately analyzed. This was followed by simulation on the device structure designs using different methods such as back incidence， to improve short wavelength absorption while maintaining a high infrared absorption. The Si APD shows a peak wavelength at around 940 nm and a high photoresponse at 250 nm and 1100 nm which exceeds 15% of the peak responsivity. This type of device is suitable for multispectral applications and future high-precision detection.
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PEI Jin-Di, CHAI Xu-Liang, WANG Yu-Peng, ZHOU Yi
DOI:
Abstract:
In the realm of near-infrared spectroscopy， the detection of molecules has been achieved using on-chip waveguides and resonators. In the mid-infrared band， the integration and sensitivity of chemical sensing chips are often constrained by the reliance on off-chip light sources and detectors. In this study， we demonstrate an InAs/GaAsSb superlattice mid-infrared waveguide integrated detector. The GaAsSb waveguide layer and the InAs/GaAsSb superlattice absorbing layer are connected through evanescent coupling， facilitating efficient and high-quality detection of mid-infrared light with minimal loss. We conducted a simulation to analyze the photoelectric characteristics of the device. Additionally， we investigated the factors that affect the integration of the InAs/GaAsSb superlattice photodetector and the GaAsSb waveguide. Optimal thicknesses and lengths for the absorption layer are determined. When the absorption layer has a thickness of 0.3 μm and a length of 50 μm， the noise equivalent power reaches its minimum value， and the quantum efficiency can achieve a value of 68.9%. The utilization of waveguide detectors constructed with III-V materials offers a more convenient means of integrating mid-infrared light sources and achieving photoelectric detection chips.
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SHAN Yi-Fan, WU Dong-Hai, XIE Ruo-Yu, ZHOU Wen-Guang, CHANG Fa-Ran, LI Nong, WANG Guo-Wei, JIANG Dong-Wei, HAO Hong-Yue, XU Ying-Qiang, NIU Zhi-Chuan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
InAs/InAsSb type-II superlattice （T2SL） materials hold great promise for the development of mid-wavelength infrared photodetectors operating at high temperatures， as they avoid the defects caused by Ga atoms in InAs/GaSb T2SL and exhibit long minority carrier lifetime. To reduce the dark current， minority carrier unipolar barrier structures， such as nBn detectors， are commonly employed. In mid-wavelength infrared InAs/InAsSb T2SL nBn photodetectors， the multielement alloy such as AlAsSb is typically utilized as the barrier layer to block the transport of majority carriers. However， the small valence band offset （VBO） between the barrier and absorption layers leads to the saturation of photocurrent at high bias voltage， resulting in increased dark current. In this work， an AlAsSb/InAsSb T2SL barrier was designed to eliminate the VBO and reduce the bias dependency of quantum efficiency. The results show that the fabricated nBn photodetector exhibits a 50% cutoff wavelength of 4.5 μm at 150 K. The optical response of the photodetector saturates under a small bias of -50 mV， achieving a peak responsivity of 1.82 A/W at 3.82 μm and a quantum efficiency of 58.8%. At 150 K and -50 mV applied bias， the photodetector exhibits a dark current density of 2.01×10-5 A/cm2 and a specific detectivity of 6.47×1011 cm·Hz1/2/W.
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YANG Mo-Xuan, ZHAO Yuan-Meng, LIU Hao-Xin, LIU Yi, WU You, ZHANG Cun-Lin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The performance of radiation sources and detectors currently limits terahertz imaging technology， which still requires further improvement in terms of detail resolution， imaging speed， and noise suppression. This paper proposes a terahertz image super-resolution algorithm based on spatial curve filling. The ViT （Vision Transformer） structure backbone network is utilized to extract terahertz image features through an attention mechanism. A Hilbert spatial curve is constructed to reconstruct the image according to the feature map using the curve filling method. Lightweight one-dimensional convolution processing is used for reconstructing image features， while inverse transformation of reconstructed maps restores the image"s spatial structure. Finally， pixel reorganization enables up sampling to obtain an output image with enhanced object contour and details. Experimental results show that compared with conventional ViT structures， this proposed method improves Peak Signal-to-Noise Ratio （PSNR） by 0.81 dB and Structural Similarity Index （SSIM） by 0.0074， which effectively inhibits the noise influence on texture and significantly improves the resolution and image quality.
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CHENG Ru-Min, SUN Jia-Hao, WU Jia-Gui, GUO Deng-Ji, XU Jiao, YANG Jun-Bo, YAN Pei-Guang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The optical frequency comb （OFC） generation of 2 μm silicon nitride microcavity is investigated. Dispersion modulation of silicon nitride waveguides is carried out by geometrical design， appropriate bus waveguide dimensions are selected， and the thermal refraction noise of silicon nitride microcavities at different modulation frequencies is discussed by the thermal absorption theory. The nonlinear Schr?dinger equation is used as the basic model to study the evolution of the cavity under different dispersion effects. The numerical results show that silicon nitride is able to observe the hysteretic state transition of the system， i.e.， the relaxation oscillation phenomenon during the transition of the system to the stable domain， more clearly in the 2 μm band， and at the same time， the cavity is able to transition to the steady state soliton faster under the action of higher-order dispersion， which provides a scheme to study the respiratory soliton.
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BAI Zhi-Zhong, HUANG Ming, XU Zhi-Cheng, ZHOU Yi, LIANG-Zhao Ming, YAO Hua-Cheng, CHEN Hong-Lei, DING Rui-Jun, CHEN Jian-Xin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this paper， we report research results of 1280×1024 dual-color mid-wavelength infrared InAs/GaSb superlattice focal plane arrays. The detector structure is PN-NP epitaxial multilayer and the signal is read out by sequential mode. The superlattice structure was grown on GaSb substrate using molecular beam epitaxy （MBE） technology. The respective structures of each absorption region are Mid-Wavelength 1（MW1）： 6 ML （InAs） /7 ML （GaSb） and Mid-Wavelength 2 （MW2）： 9 ML （InAs） /7 ML （GaSb）. The pixel center distance of the detector is 12 μm. At 80 K measurements， the detector has spectral response wavelength of 3-4 μm and 3.8-5.2 μm respectively； The MW1 detector has a peak detectivity of 6.32×1011 cmHz1/2W-1； The MW2 detector has a peak detectivity of 2.84×1011 cmHz1/2W-1. Infrared images of both wavebands have been taken using infrared imaging test by adjusting the device voltage bias. It’s the first time 1280 × 1024 InAs/GaSb Type II superlattice mid-wave length two-color infrared focal plane detector has been reported in China.
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KANG Ya-Ru, DONG Hui, LIU Jing, HUANG Zhen, LI Zhao-Feng, YAN Wei, WANG Xiao-Dong
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
For the high-electron-mobility transistor （HEMT） terahertz detector with a side-gate structure， a physical model for DC transport and terahertz detection of the device was constructed. Using a self-alignment process， well-shaped and reliable contacts for the side-gate structure were successfully fabricated， effectively solving contact issues between the dual gates and the mesa. Ultimately， terahertz detectors with different gate widths （200 nm， 800 nm， and 1400 nm） of side-gate GaN/AlGaN HEMTs were obtained. DC tests revealed a clear linear relationship between the gate widths of different devices and their threshold voltages， confirming the DC transport model of the side-gate HEMT terahertz detector. These results provide experimental verification and guidance for the theoretical model of the complete side-gate HEMT terahertz detector， offering significant support for the development of side-gate HEMT terahertz detectors.
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WANG Shuai, CHENG Ai-Qiang, GE Chen, CHEN Dun-Jun, LIU Jun, DING Da-Zhi
DOI:
Abstract:
With the analysis of experiment and theory on GaN HEMT devices under DC sweep， an improved model for kink effect based on advanced SPICE model for high electron mobility transistors （ASM-HEMT） is proposed， considering the relationship between the drain/gate-source voltage and kink effect. The improved model can not only accurately describe the trend of the drain-source current with the current collapse and kink effect， but also precisely fit different values of drain-source voltages at which the kink effect occurs under different gate-source voltages. Furthermore， it well characterizes the DC characteristics of GaN devices in the full operating range， with the fitting error less than 3%. To further verify the accuracy and convergence of the improved model， a load-pull system is built in ADS. The simulated result shows that although both the original ASM-HEMT and the improved model predict the output power for the maximum power matching of GaN devices well， the improved model predicts the power-added efficiency for the maximum efficiency matching more accurately， with 4% improved.
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Characteristic analysis of 1.06 μm long-cavity diode lasers based on asymmetric waveguide structures
ZHAO Ren-Ze, GAO Xin, FU Ding-Yang, ZHANG Yue, SU Peng, BO Bao-Xue
DOI:
Abstract:
In long-cavity edge-emitting diode lasers， longitudinal spatial hole burning （LSHB）， two-photon absorption （TPA） and free carrier absorption （FCA） are among the key factors that affect the linear increase in output power at high injection currents. In this paper， a simplified numerical analysis model is proposed for 1.06 μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional （1D） rate equations. The effects of LSHB， TPA and FCA on the output characteristics are systematically analyzed， and it is proposed that adjusting the front facet reflectivity and the position of the quantum well （QW） in the waveguide layer can improve the front facet output power.
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Influence of crystal temperature on femtosecond laser induced ferroelectric domain inversion process
XU Tian-xiang, WANG Sen, LIN Jin-yang, ZHAO Ru-wei, XU Tie-feng, SHENG Yan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The near-infrared femtosecond laser induced ferroelectric domain inversion in an important method in 3D nonlinear photonic crystal fabrication. Using structures produced by this technique， a series of attractive results have been achieved in optical frequency conversion and nonlinear wavefront shaping. At present， the reported laser induced domain inversion were all implemented at room temperature. For ferroelectric crystals， it would reach the Curie point during heating， and many characterizations such as coercive field which relate to domain inversion may change seriously. However， the effect of crystal temperature on femtosecond laser induced domain inversion is undefined. In this work， the strontium barium niobate （SrxBa1-xNbO3） ferroelectric crystal with the Curie point of about 70-80℃ depends on component proportion of Sr and Ba was used for domain inversion. Direct near-infrared femtosecond laser writing was implemented at the temperature of 25-65℃. The domain inversion condition was judged based on the second-harmonic pattern in the far field. The variation tendency of threshold laser power for domain inversion depends on temperature was tested and possible reason was predicted.
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YANG jun, YANG Chun-li, FANG Hui, YUAN Jun, YAN Shan-ru, LI Hua-ying, LI Bingzhe
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
As the cell size of uncooled infrared (IR) detectors progressively shrinks, it becomes increasingly important to increase detector absorption. here, an IMIAM (Insulator-Metal-Insulator-Air-Metal) cavity type metasurface uncooled IR detector structure is proposed, which effectively improves the uniformity of the photosensitive layer while enhancing the absorption of the detector. Utilizing systematic simulation and optimization, it has achieved almost perfect absorption in the Long Wavelength Infrared range (8~14 μm), meanwhile, it also shows excellent absorption performance in Mid Wavelength Infrared band. In this paper, the reliability of the structure is also verified by the process. this research may provide alternatives for optimizing conventional uncooled IR detectors.
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JIN Zhao, RONG Yu, QIAO Li-Ping, YU Jing-Dong, WU Fei, TIAN Dou
DOI:
Abstract:
In this paper， a dual-band graphene-based frequency selective surface （GFSS） is investigated and the operating mechanism of this GFSS is analyzed. By adjusting the bias voltage to control the graphene chemical potential between 0 eV and 0.5 eV， the GFSS can achieve four working states： dual-band passband， high-pass low-impedance， low-pass high-impedance， and band-stop. Based on this GFSS， a hexagonal radome on a broadband omnidirectional monopole antenna is proposed， which can achieve independent 360° six-beam omnidirectional scanning at 1.08 THz and 1.58 THz dual bands. In addition， while increasing the directionality， the peak gains of the dual bands reach 7.44 dBi and 6.67 dBi， respectively. This work provides a simple method for realizing multi-band terahertz multi-beam reconfigurable antennas.
太赫兹与毫米波技术
红外材料与器件
太赫兹与毫米波技术
红外材料与器件
红外光谱与光谱分析
红外材料与器件
太赫兹与毫米波技术
红外材料与器件
红外及光电技术与应用
遥感技术与应用
红外光谱与光谱分析
图像处理及软件仿真
红外材料与器件
太赫兹与毫米波技术
图像处理及软件仿真
红外材料与器件
红外及光电技术与应用
红外材料与器件
图像处理及软件仿真
红外材料与器件
太赫兹与毫米波技术
红外材料与器件
太赫兹与毫米波技术
红外及光电技术与应用
红外材料与器件
太赫兹与毫米波技术
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DIFNet: SAR RFI suppression network based on domain invariant features
Abstract:
Synthetic aperture radar (SAR) is a high-resolution two-dimensional imaging radar, however, during the imaging process, SAR is susceptible to intentional and unintentional interference, with radio frequency interference (RFI) being the most common type, leading to a severe degradation in image quality. To address the above problem, numerous algorithms have been proposed. Although inpainting networks have achieved excellent results, their generalization is unclear, and whether they still work effectively in cross-sensor experiments needs further verification. Through time-frequency analysis to interference signals, we find that interference holds domain invariant features between different sensors. Therefore, this paper reconstructs the loss function and extracts the domain invariant features to improve the generalization. Ultimately, this paper proposes a SAR RFI suppression method based on domain invariant features, and embeds the RFI suppression into SAR imaging process. Compared to traditional notch filtering methods, the proposed approach not only removes interference but also effectively preserves strong scattering targets. Compared to PISNet, our method can extract domain invariant features and holds better generalization ability, and even in the cross-sensor experiments, our method can still achieve excellent results. In cross-sensor experiments, training data and testing data come from different radar platforms with different parameters, so cross-sensor experiments can provide evidence for the generalization.
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An adaptive denoising of the photon point cloud based on two-level voxel
WANG Zhen-Hua, YANG Wu-Zhong, LIU Xiang-Feng, WANG Feng- Xiang, XU Wei-Ming, SHU Rong
Abstract:
With a single-photon detector, photon-counting LiDAR (PCL) captures a large amount of background noise along with the target scattered/reflected echo signals, because of the influence of factors such as the background environment, target characteristics, and instrument performance. To accurately extract the signal photons on the ground surface from a noisy photon point cloud (PPC), this paper presents an adaptive denoising approach for PPC using two levels of voxels. First, coarse denoising is performed utilizing large-scale voxels, which are built based on the spatial distribution features of the PPC. The density of the voxel is then used to select the voxels that contained dense signal photons. Second, fine denoising with small-scale voxels is conducted. These voxels are built using the nearest neighbor distance, and a topological relationship between voxels is used to further extract voxels containing signal photons aggregated on the ground surface. Finally, this method is performed on the PPC from ATL03 datasets collected by the Ice, Cloud, and Land Elevation Satellite-2 both during daytime and at night and compared with the improved Density-Based Spatial Clustering of Applications with Noise (DBSCAN), improved Ordering Points to Identify the Clustering Structure (OPTICS), and the method used in the ATL08 datasets. The results show that the proposed method has the best performance, with precision, recall, and F1 score of 0.98, 0.97, and 0.98, respectively.
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The Research on Aircraft Altitude Estimate Method Based on Multispectral Feature Matching in Thermal Infrared
YANG Li-Feng, CHEN Zhuo, CHEN Fan-Sheng, WANG Jian-Yu
Abstract:
The acquisition of aircraft altitude information is crucial for the aviation safety and traffic control applications. Infrared remote sensing technology can accurately measure the thermal radiation information of targets, which means the potential for quantitative observation of certain characteristics of aircraft target. A method for estimating the altitude of airborne targets based on infrared multi-channel feature matching is proposed in this paper. Firstly, a thermal infrared radiation characteristic observation model of aircraft is established, which based on the thermal infrared radiation characteristics of large aircraft and atmospheric radiative transfer models. Secondly, based on the observation model, a spectral database of aircrafts at different altitudes and flight states under different atmospheric condition can be obtained by simulating. Thirdly, target spectral information can be extracted from remote sensing images and the altitude information can be estimated with using spectral angle matching (SAM). Finally, verification and analysis were completed using simulation data and SDGSAT-1 in-orbit data. The results indicate that the proposed method can achieve kilometer-level estimation accuracy for aircraft at cruising altitude. This method provides a new solution for estimating the altitude of aircraft and has important application potential.
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Research on highly sensitive infrared imaging detection technology based on linear avalanche device
Lin Chang-qing, ZHOU Shuang-xi, LI Lu-fang, LIU Gao-rui, SUN Hai-bin, ZHANG Yu, LIN Jia-mu, SUN Sheng-li
Abstract:
With the development of remote sensing technology, the detection sensitivity of infrared system is increasingly required. The infrared imaging detection technology based on linear avalanche device can effectively improve the detection sensitivity in high frame frequency applications. Based on the short-wave infrared linear avalanche detector assembly of 512X512, a small-aperture and lightweight infrared imaging system is designed and its performance is tested under low reverse bias. The test results show that the increase of SNR of the imaging system based on the linear avalanche infrared detector is basically linear with the multiplication factor M under short integration time, and the SNR of the system is 3 times that of the traditional camera of the same caliber.
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Infrared aircraft few-shot classification method based on cross-correlation network
HUANG Zhen, ZHANG Yong, Gong Jin-Fu
Abstract:
In response to the scarcity of infrared aircraft samples and the tendency of traditional deep learning to overfit, a few-shot infrared aircraft classification method based on cross-correlation networks is proposed. This method combines two core modules: a simple parameter-free self-attention and cross-attention. By analyzing the self-correlation and cross-correlation between support images and query images, it achieves effective classification of infrared aircraft under few-shot conditions. The proposed cross-correlation network integrates these two modules and is trained in an end-to-end manner. The simple parameter-free self-attention is responsible for extracting the internal structure of the image while the cross-attention can calculate the cross-correlation between images further extracting and fusing the features between images. Compared with existing few-shot infrared target classification models, this model focuses on the geometric structure and thermal texture information of infrared images by modeling the semantic relevance between the features of the support set and query set, thus better attending to the target objects. Experimental results show that this method outperforms existing infrared aircraft classification methods in various classification tasks, with the highest classification accuracy improvement exceeding 3%. In addition, ablation experiments and comparative experiments also prove the effectiveness of the method.
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Design and validation of RLC equivalent circuit model based on long-wave infrared metamaterial absorber
ZHAO Ji-Cong, DANG Yan-Meng, HOU Hai-Yang, LIN Ye-Fan, SUN Hai-Yan, ZHANG Kun
Abstract:
In this paper, we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures, extend its design, and characterize the parameters of the model in detail. By employing this model, we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers. A comparative analysis with Finite Difference Time Domain (FDTD) simulations demonstrated a remarkable level of consistency in the results. The designed absorbers were fabricated using micro-nano fabrication processes, and was experimentally tested demonstrate absorption rates exceeding 90% at a wavelength of 9.28 μm. The predicted results are then compared with test results. The comparison reveals good consistency in two aspects of the resonance responses, thereby confirming the rationality and accuracy of this model.
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Dual-band narrowband thermal emitter designed based on multi-objective particle swarm optimization
QIU Qianli, ZHANG Jinguo, ZHOU Dongjie, TAN Chong, SUN Yan, HAO Jiaming, DAI Ning
Abstract:
Dual-band thermal emitters with narrow bandwidths are important in various applications in the infrared field, such as in infrared sensing and infrared imaging. However, conditions for narrowband emission in different wavelengths can conflict with each other, making it difficult to achieve dual-band emitter. In this paper, a new type of lithography-free infrared dual-band thermal emitter is proposed, which consists of alternately deposited Ge and YbF3 films on Al films. The narrowband emission characteristics stem from the Tamm plasmon polaritons (TPP) that can be excited by the distributed Bragg reflector and the Al substrate under certain conditions. The geometric parameters are optimized using multi-objective particle swarm optimization. The experiment results confirm thatSdual-band emitterScan simultaneously exhibit narrowband emitter characteristics in bothSmid-wave infrared (MWIR)SandSlong-wave infrared (LWIR)Sregions. The proposed method can be used in the design of multi-band emitssion modulation applications, which can be applied in the fields of multi-gas sensing and multi-band infrared camouflage.
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Synchronous Object Detection and Matching Network Based on Infrared Binocular Vision
ZENG Chang-Wen, YANG Zhi-Yu, DAI Zuo-Xiao, GU Ming-Jian
Abstract:
The three-dimensional perception of road objects in challenging environments is crucial for the development of autonomous vehicles capable of operating in all conditions, at all hours. Infrared binocular vision mimics the human binocular system, facilitating stereoscopic perception of objects in challenging conditions such as dim or zero-light environments. The core technology for stereoscopic perception in binocular vision systems lies in accurate object detection and matching. In response to the inefficiency of the sequential implementation of object detection and matching, a synchronous object detection and matching network (SODMNet) is proposed, which is capable of synchronous detection and matching of infrared objects. SODMNet innovatively combines a object detection network with a object matching module, leveraging the deep features from the classification and regression branches as inputs for the object matching module. By concatenating these features with relative position encodings from the feature maps and processing them through a convolutional network, the network generates feature descriptors for the left and right images. The object matching is then achieved by calculating the Euclidean distances between these descriptors, thus facilitating synchronous object detection and matching in binocular vision. In addition, a novel nighttime infrared binocular dataset, annotated with targets such as pedestrians and vehicles, is presented to support the development and evaluation of the proposed network. Experimental results indicate that SODMNet achieves a significant improvement of over 84.9% in object detection mean average precision (mAP) on this dataset, with a object matching average precision (AP) of 0.5777. These results demonstrate that SODMNet is capable of high-precision, synchronized object detection and matching in infrared binocular vision, marking a significant advancement in the field.
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Wideband and High Power 3D Heterogeneous Integration Photoreceiver
XU Xiangqian, GONG Guangyu, SUN Lei, LI Yu, Kang Xiaochen, LI Simin, PAN Shilong
Abstract:
In this study, we present an innovative three-dimensional (3D) heterogeneously integrated photoreceiver, which is optimized for analog microwave optical links that demand both wide bandwidth and high input optical power. The key of this design is the uni-traveling-carrier photodiode (UTC-PD), which has been flip-chip integrated onto a microwave integrated circuit submount. This integration approach enhances the photoreceiver"s overall performance, making it ideally suitful for applications requiring wide bandwidth and high power handling capabilities. The material doping and epitaxial processes of the UTC photodiode were optimized to augment its power endurance. Meanwhile, the responsivity of the photodiode was improved through the adoption of an integrated back-illuminated lens complemented by the addition of a metallic reflective layer. By establishing a precise model of the photodiode, we have refined the bandwidth characteristics of the photoreceiver using impedance compensation and broadband matching circuit design techniques. Flip-chip bonding the photodiode chip onto the microwave integrated circuit chip has substantially mitigated the impact of interconnect circuits on high-frequency performance. Furthermore, the thermal conductivity and high-power resilience of the detector chip were enhanced via gold-tin alloy micro-bump interconnections and the design of a high thermal conductivity substrate layer. The three-dimensional heterogeneous integrated photoreceiver features a 1-dB bandwidth of 42 GHz, an RF return loss exceeding 11 dB, a responsivity surpassing 0.85 A/W, a dark current below 50 nA, and a saturated input optical power of over 120 mW.By leveraging the distinctive properties of the UTC-PD, our three-dimensional (3D) heterogeneous integrated photoreceiver design achieves superior efficiency and responsiveness, positioning it as a leading solution for cutting-edge microwave photonics applications.
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High Polarization Extinction Ratio Achieved base on thin-film lithium niobate
YANG Yong-Kang, GUO Hong-Jie, CHEN Wen-Bin, QU Bai-Ang, Tan Man-Qing, GUO Wen-Tao, Yu Zhi-Guo, Liu Hai-Feng
Abstract:
This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform, and the chip is formed on the surface of the lithium niobate thin film. The chip, with a length of just 20 micrometers, achieved a measured polarization extinction ratio of 29dB at a 1550nm wavelength. This progress not only proves the possibility of achieving a high extinction ratio on a lithium niobate thin film platform, but also offers important technical references for future work on polarization beam splitters, integrated fiber optic gyroscopes, and beyond.
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Semi-Floating Gate Ferroelectric Phototransistor Optoelectronic Integrated Devices
SHANG Jia-Le, CHEN Yan, YAN Hao-Ran, DI Yun-xiang, HUANG Xin-Ning, Lin Tie, MENG Xiang-Jian, WANG Xu-Dong, CHU-Jun-Hao, WANG Jian-Lu
Abstract:
In the realm of optoelectronics, photodetectors play a pivotal role, with applications spanning from high-speed data communication to precise environmental sensing. Despite the advancements, conventional photodetectors grapple with challenges with response speed and dark current. In this study, we present a photodetector based on a lateral MoTe2 p-n junction, defined by a semi-floating ferroelectric gate. The strong ferroelectric field and the depletion region of the p-n junction in the device are notably compact, which serves to diminish the carrier transit time, thereby enhancing the speed of the photoelectric response. The non-volatile MoTe2 homojunction, under the influence of external gate voltage pulses, can alter the orientation of the intrinsic electric field within the junction. As a photovoltaic detector, it achieves an ultra-low dark current of 20 pA, and a fast photo response of 2 μs. The spectral response is extended to the shortwave infrared range at 1550 nm. Furthermore, a logic computing system with light/no light as binary input is designed to convert the current signal to the voltage output. This research not only underscores the versatility of 2D materials in the realm of sophisticated photodetector design but also heralds new avenues for their application in energy-efficient, high-performance optoelectronic devices.
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Progressive spatio-temporal feature fusion network for infrared small-dim target detection
ZENG Dan, WEI Jian-Ming, ZHANG Jun-Jie, CHANG Liang, HUANG Wei
Abstract:
To avoid the accumulation of estimation errors from explicitly aligning multi-frame features in current infrared small-dim target detection algorithms, and to alleviate the loss of target features due to network downsampling, a progressive spatio-temporal feature fusion network is proposed. The network utilizes a progressive temporal feature accumulation module to implicitly aggregate multi-frame information and utilizes a multi-scale spatial feature fusion module to enhance the interaction between shallow detail features and deep semantic features. Due to the scarcity of multi-frame infrared dim target datasets, a highly realistic semi-synthetic dataset is constructed. Compared to the mainstream algorithms, the proposed algorithm improves the probability of detection by 4.69% and 4.22% on the proposed dataset and the public dataset, respectively.
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Visible to near-infrared photodetector based on organic semiconductor single crystal
LI Xiang, HU Jin-Han, ZHONG Zhi-Peng, CHEN Yu-Zhong, WANG Zhi-Qiang, SONG Miao-Miao, WANG Yang, ZHANG Lei, LI Jian-Feng, HUANG Hai
Abstract:
Organic semiconductor materials have shown unique advantages in the development of optoelectronic devices due to their ease of preparation, low cost, lightweight, and flexibility. In this work, we explored the application of the organic semiconductor Y6-1O single crystal in photodetection devices. Firstly, Y6-1O single crystal material was prepared on a silicon substrate using solution droplet casting method. The optical properties of Y6-1O material were characterized by polarized optical microscopy, fluorescence spectroscopy, etc., confirming its highly single crystalline performance and emission properties in the near-infrared region. Phototransistors based on Y6-1O materials with different thicknesses were then fabricated and tested. It was found that the devices exhibited good visible to near-infrared photoresponse, with the maximum photoresponse in the near-infrared region at 785 nm. The photocurrent on/off ratio reaches 102, and photoresponsivity reaches 16 mA/W. It was also found that the spectral response of the device could be regulated by gate voltage as well as the material thickness, providing important conditions for optimizing the performance of near-infrared photodetectors. This study not only demonstrates the excellent performance of organic phototransistors based on Y6-1O single crystal material in near-infrared detection but also provides new ideas and directions for the future development of infrared detectors.
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Serialized orthogonal matching pursuit fusing image domain information for attributed scattering center extraction in SAR images
Abstract:
Aiming to address the issue of high complexity in estimating the parameters of the Attribute Scattering Center Model (ASCM) in Synthetic Aperture Radar (SAR) images, a sparse representation parameter estimation method that integrates information from the image domain is proposed. Firstly, the improved watershed algorithm is used to segment the scattering centers of different regions. Subsequently, based on the segmentation results, the frequency domain sparse representation dictionary is decoupled and applied in a serialized manner for scattering center parameter estimation using orthogonal matching pursuit to reduce algorithm complexity. Based on simulated data and measured MSTAR data, the effectiveness and efficiency of the proposed parameter extraction method were validated, and the optimization of theoretical complexity was analyzed. The results indicate that this method can significantly reduce the time and space complexity of the algorithm while achieving results close to those of the conventional orthogonal matching pursuit algorithm. The proposed method can be used for the efficient extraction of scattering center parameters in SAR images.
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Correlation Between the whole small recess offset and Electrical Performance of InP-based HEMTs
GONG Hang, ZHOU Fu-Gui, FENG Rui-Ze, FENG Zhi-Yu, LIU Tong, SHI Jing-Yuan, SU Yong-Bo, JIN Zhi
Abstract:
In this work, we investigate the impact of the whole small recess offset on DC and RF characteristics of InP high electron mobility transistors (HEMTs). Lg = 80 nm HEMTs are fabricated with a double-recessed gate process. We focus on their DC and RF responses, including the maximum transconductance (gm_max), ON-resistance (RON), current-gain cutoff frequency (fT), and maximum oscillation frequency (fmax). The devices have almost same RON. The gm_max improves as the whole small recess moves toward the source. However, a small gate to source capacitance (Cgs) and a small drain output conductance (gds) lead to the largest fT, although the whole small gate recess moves toward the drain leads to the smaller gm_max. According to the small-signal modeling, the device with the whole small recess toward drain exhibits an excellent RF characteristics, such as fT = 372 GHz and fmax = 394 GHz. This result is achieved by paying attention to adjust resistive and capacitive parasitics, which play a key role in high-frequency response.
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Research on error analysis and instrument parameter configuration of emissivity measurement of multispectral radiometric method based on slow-change assumption
Luan Yi-Fei, Wang Xiang, Gu Luo, Lin Yue, Yang Qiu-Jie, He Zhi-Ping
Abstract:
Emissivity, as a key parameter to characterize the radiation properties of an object, and its accurate measurement is of great value for high-temperature target identification, characterization of material modification, and regulation of metal smelting process. The emissivity measurement by multispectral radiation method has become a research hotspot because of its advantages of non-contact and fast measurement speed, and its measurement accuracy is determined by the solution accuracy of the underdetermined system of equations. At present, the research on the solution accuracy of the underdetermined system of equations mainly focuses on the error of the equation solving algorithm, ignoring the measurement error of the spectrometer itself, which leads to the failure of controlling the system error in a reasonable way. In this paper, based on the assumption of retardation with wide application range and high measurement accuracy, the influence of the number of spectral channels and signal-to-noise ratio on the emissivity measurement error under different conditions is simulated, the parameter configurations of the spectrometer under the corresponding conditions are determined, and the effect of emissivity measurement is experimentally verified. The experimental results show that, using the multispectral radiation method based on the slow-change assumption, the number of spectral channels of the spectrometer should be not less than 400 and the signal-to-noise ratio should not be less than 1000 in order to make the blackbody emissivity measurement error less than 1%; for the targets with complex emissivity changes, the spectrometer should have at least 1,000 spectral channels and signal-to-noise ratios of more than 1,200 in order to make the measurement error less than 1%. Comprehensive consideration of the algorithm error and spectrometer parameter matching relationship is the key to rationally control the system error, and more accurate emissivity measurement results can be obtained, which provides a new basis and solution for the application of multispectral radiation method to accurately measure the emissivity, which is of great significance for the accurate identification of high-temperature targets and the application of the related fields.
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Enhancement of mid-wavelength infrared absorbance by alkane-grafted Ti3C2Tx MXene flakes
赵振宇, Hideaki Kitahara, Zhang Chen-Hao, Masahiko Tani
Abstract:
An enhancement of mid-wavelength infrared absorbance is achieved via a cost-effectively chemical method to bend the flakes by grafting two types of alkane octane (C8H18) and dodecane (C12H26) onto the surface terminals respectively. The chain-length of alkane exceeds the bond-length of surface functionalities Tx (=O,-OH,-F) so as to introduce intra-flake and inter-flake strains into Ti3C2Tx MXene. The electronic microscopy (TEM/AFM) shows obvious edge-fold and tensile/compressive deformation of flake. The alkane termination increases the intrinsic absorbance of Ti3C2Tx MXene from no more than 50% down to more than 99% in the mid-wavelength infrared region from 2.5 μm to 4.5 μm. Such an absorption enhancement attribute to the reduce of infrared reflectance of Ti3C2Tx MXene. The C-H bond skeleton vibration covers the aforementioned region and partially reduce the surface reflectance. Meanwhile, the flake deformation owing to edge-fold and tensile/compression increase the specific surface area so as to increase the absorption as well.
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Study on Multi-wavelength Thin Film Thickness Determination Method
SHI Ce, XIE Mao-Bin, ZHENG Wei-Bo, JI Ruo-Nan, WANG Shao-Wei, LU Wei
Abstract:
This work introduces a novel method for measuring thin film thickness, employing a multi-wavelength method that significantly reduces the need for broad-spectrum data. Unlike traditional techniques that require several hundred spectral data points, the multi-wavelength method achieves precise thickness measurements with data from only 10 wavelengths. This innovation not only simplifies the process of spectral measurement analysis but also enables accurate real-time thickness measurement on industrial coating production lines. The method effectively reconstructs and fits the visible spectrum (400-800 nm) using a minimal amount of data, while maintaining measurement error within 7.1%. This advancement lays the foundation for more practical and efficient thin film thickness determination techniques in various industrial applications.
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75-110 GHz wideband Frequency Tripler Chip Based on Planar Schottky Diode
CHEN Yan, MENG Fan-Zhong, XUE Hao-Dong, ZHANG Ao, GAO Jianjun
Abstract:
Based on GaAs planar Schottky diode process, a W band wideband frequency tripler MMIC is designed with a reverse parallel diode pair in this paper. By combining of finite element method and equivalent circuit method, an accurate equivalent circuit model of the planar Schottky diode is built in the frequency range of 10~280GHz. The nonlinear harmonic balance tool is utilized to achieve the optimal frequency tripler design in W band. The measurement results show that the frequency multiplication loss is less than 15dB under 17dBm driving power, efficiency up to 6.7%. The chip size is 0.80mm×0.65mm×0.05mm．
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Research of power improvement of a LD directly-pumped mid-infrared pulse solid-state laser
ZHANG Meng, YANG Xi, GUO Jia-Wei, CAI He, WU Xin-Yang, HAN Ju-Hong, WANG Shun-Yan, WANG You
Abstract:
A LD directly-pumped solid-state laser is considered to be one of the most promising mid-infrared light sources because of its simple principle, small size, and compact structure for the generation of mid-infrared (MIR) lasers in the 3~5 μm band. However, the quantum defect of LD directly-pumped MIR solid-state lasers will be much larger than that of ordinary near-infrared LD pumped solid-state lasers, which may lead to thermal damage and limit their development. In order to solve this problem, the methods of reducing the specific surface area of the crystal and improving the thermal energy released by the crystal structure are discussed, and the optimal length of the laser crystal is determined. The cooling structures of barium yttrium fluoride laser crystals (Ho3+:BY2F8) of different lengths were studied by thermal simulation using COMSOL software. The experimental results show that the output power can be increased and the thermal stress in the laser crystal can be alleviated by using the laser crystal whose length is slightly shorter than that of the cooler. The final experiment shows that when the pump repetition rate is 15 Hz and the pulse width is 90 μs, the output wavelength of the laser is about 3.9 μm and the single pulse energy is 7.28 mJ, which is about 3 times that of the crystal-I. Such results should be another breakthrough of our team since the first directly-pumped solid-state MIR laser was realized more than a year ago. It might pave the way for the construction of a feasible MIR laser in the near future.
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Deep Plug-and-Play Self-Supervised Neural Networks for Spectral Snapshot Compressive Imaging
Zhang Xing-Yu, Zhu Shou-Zheng, Zhou Tian-Shu, Qi Hong-Xing, Wang Jian-Yu, Li Chun-Lai, Liu Shi-Jie
Abstract:
The coded aperture snapshot spectral imaging system, based on compressed sensing theory, functions as an capable of efficiently acquiring compressed two-dimensional spectral data. This data is subsequently decoded into three-dimensional spectral data through a deep neural network. However, training the deep neural network necessitates a substantial amount of clean data, which is often challenging to obtain. To address the issue of insufficient training data for deep neural network, a self-supervised hyperspectral denoising neural network is proposed, leveraging the concept of neighborhood sampling. This network is integrated into the deep plug-and-play framework, enabling self-supervised spectral reconstruction. The study also examines the impact of different noise degradation models on the final reconstruction quality. Experimental results demonstrate that compared with supervised learning method, the self-supervised learning method enhances the average peak signal-to-noise ratio by 1.18dB and improves the structural similarity is improved by 0.009. Additionally, it achieves superior visual reconstruction outcomes without relying on clean data as labels.
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Study on photoelectric performance of ultra-small pixel pitch micro-mesa InGaAs detector
TIAN Yu, YU Chun-Lei, LI Xue, SHAO Xiu-Mei, LI Tao, YANG Bo, YU Xiao-Yuan, CAO Jia-Shen, GONG Hai-Mei
Abstract:
The pursuit of ultra-small pixel pitch InGaAs detectors necessitates a meticulous approach to addressing challenges associated with crosstalk reduction and dark current minimization. By developing the fabrication process technology of micro-mesa InGaAs detector, a test structure featuring a micro-mesa InGaAs photosensitive chip with 10μm and 5μm pixel pitch was successfully prepared. Subsequently, a comprehensive investigation was conducted to analyze the impact of the micro-mesa structure on crosstalk and dark current characteristics of the InGaAs detector. The obtained results revealed the efficacy of the micro-mesa structure in effectively suppressing crosstalk between adjacent pixels when the isolation trench etches into the absorption layer. However, a noteworthy challenge emerged as the fabrication processes induced material damage, leading to a considerable increase in recombination current and ohmic leakage current. This adverse effect, in turn, manifested as a dark current escalation by more than one order of magnitude. The significance of these findings lies in offering a novel perspective for the manufacturing of ultra-small pixel pitch InGaAs focal plane detectors.
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GaSb-based tensile-strained Ge quantum dots for mid-infrared lasers
Cao You-Xiang, Dai Jin-Meng, Zhang Li-Yao
Abstract:
Ge can be converted into direct bandgap material under tensile strain. Pyramid-shaped Ge quantum dots (QDs) on GaSb system is proposed. The strain distribution and band structures are investigated with different QD sizes. Flat Ge QDs are desirable for indirect to direct band gap conversion. Light emission from 1.8 μm to 5.8 μm can be achieved from Ge/GaSb QDs with the width ranges from 4 to 14 nm and the height ranges from 1 to 5 nm. A 3.1 μm laser with Ge/GaSb QDs with height of 3 nm and width of 12 nm is designed and the device performance is simulated at room temperature. The QD size fluctuations are also considered. Under the root mean square of QD size fluctuation of 0.22, the calculated optimal optical confinement factor, thickness of the waveguide, surface density of QDs are 0.013, 0.366 μm and 3.8×1010 cm-2, respectively, while the minimum threshold current density is 28.98 A/cm2. This work provides a feasible way for the fabrication of mid-infrared lasers.
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A HgTe/ZnO Quantum Dots Vertically Stacked Heterojunction Low dark current Photodetector
HUANG Xin-Ning, JIANG Teng-Teng, DI Yun-Xiang, XIE Mao-Bin, GUO Tian-Le, LIU Jing-Jing, WU Bin-Min, SHI Jing-Mei, Qin Qiang, DENG Gong-Rong, CHEN Yan, LIN Tie, SHEN Hong, MENG Xiang-jian, WANG Xu-Dong, CHU Jun-Hao, GE Jun, WANG Jian-lu
Abstract:
Colloidal quantum dots (CQDs) are affected by the quantum confinement effect, which makes their bandgap tunable. This characteristic allows these materials to cover a broader infrared spectrum, providing a cost-effective alternative to traditional infrared detector technology. Recently, thanks to the solution processing properties of quantum dots and their ability to integrate with silicon-based readout circuits on a single chip, infrared detectors based on HgTe CQDs have shown great application prospects. However, facing the challenges of vertically stacked photovoltaic devices, such as barrier layer matching and film non-uniformity, most devices integrated with readout circuits still use a planar structure, which limits the efficiency of light absorption and the effective separation and collection of photo-generated carriers. Here, by synthesizing high-quality HgTe CQDs and precisely controlling the interface quality, we have successfully fabricated a photovoltaic detector based on HgTe and ZnO QDs. At a working temperature of 80 K, this detector achieved a low dark current of 5.23×10-9 A cm-2, a high rectification ratio, and satisfactory detection sensitivity. This work paves a new way for the vertical integration of HgTe CQDs on silicon-based readout circuits, demonstrating their great potential in the field of high-performance infrared detection.
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Angular-tunable on-chip coding metasurface enabled by phase-change material with immersion liquid
LI Xue-Nan, ZHAO Zeng-Yue, YU Fei-Long, CHEN Jin, LI Guan-Hai, LI Zhi-Feng, CHEN Xiao-Shuang
Abstract:
Metasurfaces provide a potent platform for the dynamic manipulation of electromagnetic waves. Coupled with phase-change materials, they facilitate the creation of versatile metadevices, showcasing various tunable functions based on the transition between amorphous and crystalline states. However, the inherent limitation in tunable states imposes constraints on the multiplexing channels of metadevices. Here, this paper introduce a novel approach—a multi-functional metadevice achieved through the two-level control of the encoding phase-change metaatoms. Utilizing the phase-change material Ge2Sb2Se4Te1 (GSST) and high refractive-index liquid diiodomethane (CH2I2), this paper showcase precise control over electromagnetic wave manipulation. The GSST state governs the tunable function, switching it ON and OFF, while the presence of liquid in the hole dictates the deflection angle when the tunable function is active. Importantly, our tunable coding metasurface exhibits robust performance across a broad wavelength spectrum. The incorporation of high refractive-index liquid extends the regulatory dimension of the metadevice, enabling dynamic switching of encoding bit levels. This two-level tunable metadevice, rooted in phase-change materials, presents a promising avenue for the dynamic control of functions.
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Ion Implantation Process and Lattice Damage Mechanism of Boron Doped Crystalline Germanium
HABIBA Um E, CHEN Tian-Ye, LIU Chi-Xian, DOU Wei, LIU Xiao-Yan, LING Jing-Wei, PAN Chang-Yi, WANG Peng, DENG Hui-Yong, SHEN Hong, DAI Ning
Abstract:
The response wavelength of the boron doped germanium (Ge:B) blocked-impurity-band (BIB) structured infrared detector can reach 200μm, which is the most important very long wavelength infrared astronomical detector. The ion implantation method greatly simplifies the fabrication process of the device, but it is easy to cause lattice damage, introduce crystalline defects, and lead to the increase of the dark current of detectors. Herein, the boron-doped germanium ion implantation process was studied, and the involved lattice damage mechanism was discussed. Experimental conditions involved using 80 keV energy for boron ion implantation, with doses ranging from 1×10^13 to 1×10^15cm^-2. After implantation, thermal annealing at 450°C was implemented to optimize dopant activation and mitigate the effects of ion implantation. Various sophisticated characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) were used to clarify lattice damage. At lower doses, no notable structural alterations were observed. However, as the dosage increased, specific micro distortions became apparent, which could be attributed to point defects and residual strain. The created lattice damage was recovered by thermal treatment, but an irreversible strain induced by implantation still existed at the high doses.
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2001,20(3):184-188, DOI:
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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2002,21(3):161-166, DOI:
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, DOI:
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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HU Zhi Gao WANG Gen Shui HUANG Zhi Ming CHU Jun Hao
2002,21(3):175-179, DOI:
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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FuY ChiragwandiZ GoethbergP WillanderM
2003,22(6):401-405, DOI:
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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XU Yun, WANG Yi-Ming, WU Jing-Zhu, ZHANG Xiao-Chao
2010,29(1):53-56, DOI:
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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CHENG Jian, ZHOU Yue, CAI Nian, YANG Jie
2006,25(2):113-117, DOI:
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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2010,29(1):63-68, DOI:
Abstract:
A novel infrared target extraction algorithm based on particle swarm optimization particle filter(PSOPF) was proposed. The problem of infrared target extraction was analyzed and solved in the view of state estimation. In the framework of particle filter, the threshold state space on the gray-variance weighted information entropy and the grey value of each pixel was based on extraction results evaluation function, which integrated grey, entropy, gradient and spatial distribution of pixels. Finally, the weighted average of all the particles was used as target extraction threshold. The experiment results prove that the proposed algorithm is effective and robust.
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2010,29(1):69-74, DOI:
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.
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2008,27(2):123-128, DOI:
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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SUN Jun-Ding, DING Zhen-Guo, ZHOU Li-Hua
2005,24(2):135-139, DOI:
Abstract:
A new image retrieval algorithm based on image entropy and spatial distribution entropy was presented. At first a more robust method, which can remove the influence of the symmetry of entropy, was proposed to extract the global color feature. Then color spatial distribution entropy vector for each color channel was also introduced to represent the spatial color information. After that, the moments were adopted to reduce the dimension of color spatial distribution entropy. In the end, a low dimensional vector which includes the global and spatial information was used as index for color image retrieval. The experiment results show that the new method gives better performance than color histogram.
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EFFECTS OF APODIZATION FUNCTIONS OF IMAGING FOURIER TRANSFORM SPECTROMETER ON RECONSTRUCTED SPECTRUM
ZHANG Wen-Juan, ZHANG Bing, ZHANG Xi, GAO Lian-Ru, ZHANG Wei
2008,27(3):227-233, DOI:
Abstract:
随着搭载干涉成像光谱仪HJY20-1-A的我国环境与减灾遥感卫星HJ-1A即将发射,我国干涉光谱成像研究也从实验室开始走向实用化.在干涉光谱成像过程中,切趾函数处理是干涉成像光谱仪光谱复原过程中的一个重要环节,对复原光谱的精度有着极其重要的影响.根据HJY20-1-A的参数设置,文中首先模拟了24种典型地物对应于HJY20-1-A和其它最大光程差设置的干涉成像光谱仪数据,在不同切趾函数作用下的复原光谱,结果表明Hanning函数是其中最有效、最为稳定的切趾函数,同时发现切趾函数的应用虽然可以提高复原光谱的精度,但与真实光谱仍存在一定差距,尤其对应HJY20-1-A,复原光谱的精度更加有限.在以上分析基础上,提出了基于仪器线型函数标准化的光谱复原改进算法,实验结果证实了该方法可以显著提高复原光谱精度,尤其适用于最大光程差较小的空间调制型干涉成像光谱仪.最后,就HJY20-1-A复原光谱对3种典型植被指数求解,进一步证明了该方法的有效性.
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2001,20(3):207-210, DOI:
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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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, DOI:
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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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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ZHANG Yu-Hong, CHEN Zhan-Guo, JIA Gang, SHI Bao, REN Ce, LIU Xiu-Huan, WU Wen-Qing
2008,27(3):165-169, DOI:
Abstract:
首次测量了硅材料在1.3μm波长处,基于克尔效应和弗朗兹-凯尔迪什效应的电致双折射,进而计算出三阶非线性极化率张量X(3)的分量X(3)xyxy.观测到弗朗兹-凯尔迪什效应引起的折射率变化与入射光的偏振态有关.在实验中,测得了由克尔效应引起的折射率之差为⊿n=5.49×10-16E20,而弗朗兹-凯尔迪什效应引起的折射率之差为⊿n'=2.42×10-16E2.50.
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WU Yan 1), 2) ZHANG Li Ming 2)
2002,21(3):189-194, DOI:
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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WU Xiang, PEI Zhi-Bin, QU Shao-Bo, XU Zhuo, ZHANG Jie-Qiu, MA Hua, WANG Jia-Fu, WANG Xin-Hua, ZHOU Hang
2011,30(5):469-474, DOI:
Abstract:
By adjusting the effective permittivity of the unit cell, a new method of constructing metamaterial band-pass frequency selective surface was proposed. The effective permittivity of continuous conducting wires is negative below the plasma frequency and thus a stop-band occurs. By combining the continuous conducting wires with cut wires, we realized a one-dimensional frequency selective surface. Both the theory analysis and simulation results demonstrated the facility and feasibility of the method. We also designed a wide-angle and polarization-independent frequency selective surface based on this method. Two samples were fabricated to validate the proposed method; the experiment results were fairly consistent with the simulation results. The proposed method eliminates the complicated calculation and excessive parameter optimization process. It paves a new way of designing frequency selective surfaces and is of important reference values for fabricating THz frequency selective surface as well as multi-band, tunable and miniaturized frequency selective surfaces.
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SHI Jun-Sheng 1, 2, JIN Wei-Qi 1, WANG Ling-Xue 1
2005,24(3):236-240, DOI:
Abstract:
With the development and the application of visible-IR image fusion techniques in color vision night, evaluating the performance of image-fused algorithms is becoming an important aspect. In this study, three basic visual evaluation factors, target detection, details and colorfulness, were presented for evaluating perceptual quality of color fused images, and the degree of correlation between the perceptual quality and the three evaluation factors was investigated. Visual evaluation experiment on the color images fused visible and IR images of ten scenes by four fusion algorithms was conducted. The experimental results show that the fuesd images have good performances in target detection, the correlation coefficient between the perceptual qulity and details is 0.89, and the correlation coefficient between the perceptual qulity and colorfulness is 0.75 . It indicates that details are the main factor and the colorfulness plays an important role when targets are beyong the detected level.
