Volume 43,2024 Issue 6

Infrared Physics, Materials and Devices

• Enhancement of mid-wavelength infrared absorbance by alkane-grafted Ti₃C₂T_x MXene thin-films

  ZHAO Zhen-Yu, KITAHARA Hideaki, ZHANG Chen-Hao, TANI Masahiko

  2024,43(6):733-737, DOI: 10.11972/j.issn.1001-9014.2024.06.001

  Abstract: (14) HTML (1) PDF (1.84 MKB)(4)

  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 T_x （=O，-OH，-F） so as to introduce intra-flake and inter-flake strains into Ti₃C₂T_x MXene. The electronic microscopy （TEM/AFM） shows obvious edge-fold and tensile/compressive deformation of flake. The alkane termination increases the intrinsic absorbance of Ti₃C₂T_x MXene from no more than 50% up to more than 99% in the mid-wavelength infrared region from 2.5 μm to 4.5 μm. Such an absorption enhancement attributes to the reduce of infrared reflectance of Ti₃C₂T_x MXene. The C-H bond skeleton vibration covers the aforementioned region and partially reduces the surface reflectance. Meanwhile， the flake deformation owing to edge-fold and tensile/compression increases the specific surface area so as to increase the absorption as well. These results have applicable value in the area of mid-infrared camouflage.

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• 12.5 μm 1024×1024 long-wavelength infrared InAs/GaSb Type II superlattice focal plane arrays

  BAI Zhi-Zhong, HUANG Ming, XU Zhi-Cheng, ZHOU Yi, ZHU Yi-Hong, SHEN Yi-Ming, ZHANG Jun-Lin, CHEN Hong-Lei, DING Rui-Jun, CHEN Jian-Xin

  2024,43(6):738-743, DOI: 10.11972/j.issn.1001-9014.2024.06.002

  Abstract: (11) HTML (2) PDF (1.22 MKB)(8)

  Abstract:

  In this paper， the research results of 12.5 μm long-wavelength infrared InAs/GaSb superlattice focal plane arrays were reported. The superlattice structure was grown on GaSb substrate using molecular beam epitaxy （MBE） technology. The respective structure of absorption region is 15ML （ InAs） /7ML （ GaSb）. The detector adopts PBπBN double barrier structure to suppress the dark current. A long-wave focal plane detector with the size of 1 024×1 024 and the pixel center-to-center distance of 18 μm was developed. The detector was packaged by a metal dewar， and a superlattice long-wavelength detector cryocooler assembly was formed by coupling with a refrigerator. Measured at 60 K， the detector has 50% cut-off wavelength of 12.5 μm. The detector has a peak detectivity of 6.6×10¹⁰ cm?Hz^1/2/W ， dead pixels rate of 1.05% and a noise equivalent temperature difference （NETD） of 21.2 mK.The infrared images have been taken clearly using this infrared imaging detector.

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• Extracting the effective mass of fewer layers 2D h-BN nanosheets using the Fowler-Nordheim tunneling model

  QIN Jia-Yi, LUO Man, CHENG Tian-Tian, MENG Yu-Xin, ZU Yuan-Ze, WANG Xin, YU Chen-Hui

  2024,43(6):744-748, DOI: 10.11972/j.issn.1001-9014.2024.06.003

  Abstract: (9) HTML (0) PDF (969.83 KKB)(3)

  Abstract:

  Hexagonal boron nitride （h-BN） is found to have widespread application， owing to its outstanding properties， including gate dielectrics， passivation layers， and tunneling layers. The current studies on the fundamental physical properties of these ultrathin h-BN films and the electron tunneling effect among them are inadequate. In this work， the effective mass in h-BN was successfully determined through a combined approach of experimental and theoretical research methods by fitting the current-voltage curves of metal/insulator/metal structures. It was observed that within a range of 4-22 layers， the effective mass of h-BN exhibits a monotonic decrease with an increase in the number of layers. The physical parameters of the Fowler-Nordheim tunneling model in the context of electron tunneling in h-BN are precisely ascertained by utilizing the extracted effective mass. Additionally， the impact of fixed charges at the metal/h-BN interface and various metal electrode types on Fowler-Nordheim tunneling within this structure is investigated utilizing this physical parameter in Sentaurus TCAD software. This work is informative and instructive in promoting applications in the fields of h-BN related infrared physics and technology.

• 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

  2024,43(6):749-754, DOI: 10.11972/j.issn.1001-9014.2024.06.004

  Abstract: (8) HTML (1) PDF (2.75 MKB)(4)

  Abstract:

  The response wavelength of the blocked-impurity-band （BIB） structured infrared detector can reach 200 μm， 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 110¹³ cm^-2 to 310¹⁵ cm^-2. After implantation， thermal annealing at 450 ℃ 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， however， an irreversible strain induced by implantation still existed at heavily dosed samples.

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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

  2024,43(6):755-761, DOI: 10.11972/j.issn.1001-9014.2024.06.005

  Abstract: (6) HTML (1) PDF (3.06 MKB)(10)

  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， structures featuring a micro-mesa InGaAs photosensitive chip with 10 μm and 5 μm pixel pitch were 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 efficiency of the micro-mesa structure in effectively suppressing crosstalk between adjacent pixels when the isolation trench etched 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 offers a novel perspective for the manufacturing of ultra-small pixel pitch InGaAs focal plane detectors.

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• Research on polarization control of MOPA semiconductor laser

  WANG Hao-Miao, HE Yu-Wen, LI Yi, HU Yao, ZHANG Liang, DU Wei-Chuan, GAO Song-Xin, TANG Chun, MA Xiao-Yu, LIU Su-Ping

  2024,43(6):762-767, DOI: 10.11972/j.issn.1001-9014.2024.06.006

  Abstract: (9) HTML (0) PDF (1.40 MKB)(11)

  Abstract:

  The master oscillator power amplifier （MOPA） laser is receiving increasing attention due to its ability to achieve high power and beam quality output. In order to improve the polarization degree of MOPA laser and reduce the efficiency loss during polarization combining， InGaAs/AlGaAs compressive single quantum well was used in the active region. The optical confinement factor of TE-mode in ridge waveguide was improved by 1.35 μm deep etching， whereas the TE optical gain in tapered amplifier was increased through on-chip metal stress regulation. Combining the two schemes not only improves the degrees of polarization （DOP） of two sections， but also reduces the polarization angle difference. Finally， 11 W@15 A continuous output and over 90% DOP of the MOPA have been achieved by standard process fabrication.

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Millimeter Waves and Terahertz Technology

• 75-110 GHz wideband frequency tripler chip based on planar schottky diode

  CHEN Yan, MENG Fan-Zhong, XUE Hao-Dong, ZHANG Ao, GAO Jian-Jun

  2024,43(6):768-774, DOI: 10.11972/j.issn.1001-9014.2024.06.007

  Abstract: (7) HTML (2) PDF (1.59 MKB)(8)

  Abstract:

  Based on the GaAs planar Schottky diode process， a W band wideband frequency tripler MMIC is designed with a reverse parallel diode pair. By combining the finite element method and equivalent circuit method， an accurate equivalent circuit model of the planar Schottky diode is built in the frequency range of 10-280 GHz. The nonlinear harmonic balance tool is utilized to achieve the optimal frequency tripler design in the W band. The measurement results show that the frequency multiplication loss is less than 15 dB under 17 dBm driving power， and the efficiency up to 6.7%. The chip size is 0.80 mm×0.65 mm×0.05 mm．

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• DIFNet: SAR RFI suppression network based on domain invariant features

  LYU Wen-Hao, FANG Fu-Ping, TIAN Yuan-Rong

  2024,43(6):775-783, DOI: 10.11972/j.issn.1001-9014.2024.06.008

  Abstract: (6) HTML (0) PDF (1.15 MKB)(9)

  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. Whether they still work effectively in cross-sensor experiments needs further verification. Through the time-frequency analysis to interference signals， this work finds that interference holds domain invariant features between different sensors. Therefore， this work reconstructs the loss function and extracts the domain invariant features to improve its generalization. Ultimately， this work 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 hold 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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• Serialized orthogonal matching pursuit fusing image domain information for attributed scattering center extraction in SAR images

  LONG Bo, WANG Feng

  2024,43(6):784-796, DOI: 10.11972/j.issn.1001-9014.2024.06.009

  Abstract: (7) HTML (1) PDF (1.98 MKB)(8)

  Abstract:

  Aiming to address the issue of high complexity in estimating the parameters of the attributed 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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Infrared Spectroscopy and Remote Sensing Technology

• Analysis of emissivity measurement error and instrument parameter configuration for multispectral radiometric method based on slow-change assumption

  LUAN Yi-Fei, WANG Xiang, GU Luo, LIN Yue, YANG Qiu-Jie, HE Zhi-Ping

  2024,43(6):797-805, DOI: 10.11972/j.issn.1001-9014.2024.06.010

  Abstract: (8) HTML (0) PDF (2.47 MKB)(5)

  Abstract:

  As a key parameter for characterizing the radiation characteristics of objects， emissivity has significant value in accurate measurement for high-temperature target identification， material modification， and regulation of metal smelting process. The multispectral radiation method for measuring emissivity has become a research hotspot due to its non-contact and fast measurement speed advantages， and its measurement accuracy is determined by the solution accuracy of the underdetermined equation system. 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%. Taking into account the matching relationship between algorithm errors and spectrometer parameters is the key to effectively controlling system errors and obtaining more accurate emissivity measurement results. This provides a new basis and solution for the precise measurement of emissivity using multispectral radiation methods， which is of great significance for the accurate identification of high-temperature targets and related applications.

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Infrared Optoelectronic System and Application Technology

• 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

  2024,43(6):806-812, DOI: 10.11972/j.issn.1001-9014.2024.06.011

  Abstract: (10) HTML (0) PDF (1.43 MKB)(9)

  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 introduces 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 showcases 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.

• 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

  2024,43(6):813-819, DOI: 10.11972/j.issn.1001-9014.2024.06.012

  Abstract: (10) HTML (0) PDF (1.23 MKB)(7)

  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.

• Research on 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

  2024,43(6):820-826, DOI: 10.11972/j.issn.1001-9014.2024.06.013

  Abstract: (8) HTML (1) PDF (2.38 MKB)(4)

  Abstract:

  An 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 single pulse energy is 7.28 mJ at the output wavelength of 3.9 μm， which is about 3 times as large as that of the crystal with the length of 10 mm （2.81 mJ）. 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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• High polarization extinction ratio achieved base on thin-film lithium niobate

  YANG Yong-Kang, GUO Hong-Jie, CHEN Wen-Bin, QU Bai-Ang, YU Zhi-Guo, TAN Man-Qing, GUO Wen-Tao, LIU Hai-Feng

  2024,43(6):827-831, DOI: 10.11972/j.issn.1001-9014.2024.06.014

  Abstract: (8) HTML (0) PDF (893.84 KKB)(6)

  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 μm， achieved a measured polarization extinction ratio of 29 dB at 1 550 nm 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 so on.

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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

  2024,43(6):832-845, DOI: 10.11972/j.issn.1001-9014.2024.06.015

  Abstract: (10) HTML (1) PDF (3.85 MKB)(6)

  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 topologicalrelationship 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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Interdisciplinary Research on Infrared Science

• 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

  2024,43(6):846-857, DOI: 10.11972/j.issn.1001-9014.2024.06.016

  Abstract: (9) HTML (2) PDF (1.24 MKB)(8)

  Abstract:

  The encoding aperture snapshot spectral imaging system， based on the compressive sensing theory， can be regarded as an encoder， which can efficiently obtain compressed two-dimensional spectral data and then decode it into three-dimensional spectral data through deep neural networks. However， training the deep neural networks requires a large amount of clean data that is difficult to obtain. To address the problem of insufficient training data for deep neural networks， a self-supervised hyperspectral denoising neural network based on neighborhood sampling is proposed. This network is integrated into a deep plug-and-play framework to achieve self -supervised spectral reconstruction. The study also examines the impact of different noise degradation models on the final reconstruction quality. Experimental results demonstrate that the self-supervised learning method enhances the average peak signal-to-noise ratio by 1.18 dB and improves the structural similarity by 0.009 compared with the supervised learning method. Additionally， it achieves better visual reconstruction results.

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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

  2024,43(6):858-870, DOI: 10.11972/j.issn.1001-9014.2024.06.017

  Abstract: (8) HTML (0) PDF (3.02 MKB)(3)

  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 the 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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• Attention guided by human keypoint for infrared-visible person re-identification

  YU Peng, TIAN Xiao-Jian, QI Nan, PIAO Yan

  2024,43(6):871-878, DOI: 10.11972/j.issn.1001-9014.2024.06.018

  Abstract: (9) HTML (2) PDF (701.39 KKB)(9)

  Abstract:

  Person re-identification is the task of retrieving a specified target from multiple data sources. The difference between infrared （IR） and visible light （VIS） images is large， and cross-modal retrieval of visible light and infrared images is one of the main challenges. In order to have the same retrieval ability even in low light or at night， the judgment needs to be achieved by combining cross-modal modeling of infrared images. In this paper， we propose a new method of guiding attention through human keypoints， where global features are split into local features by keypoint guidance， and then the original model is retrained with the generated local masks to strengthen the attention to different local information. Using this method， the model can better understand and utilize the key regions in the image， thus improving the accuracy of the person re-identification task.

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红外物理与材料器件

• Urban Tree Species Classification with Multispectral Airborne LiDAR

  Hu Peilun, Chen Yuwei, Mohammad Imangholiloo, Markus Holopainen, Wang Yicheng

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (100) HTML (0) PDF (1.27 MKB)(53)

  Abstract:

  Urban tree species provide various essential ecosystem services in cities， such as mediating urban temperature， isolating noise， fixing carbon， and mitigating the urban heat island impact. The quality of these services is influenced by species diversity， tree growth status， and the distribution and composition of trees. Traditionally， data about urban trees has been gathered through field data collection and manual interpretation of remote sensing images. In this study， we evaluate the capacity of using Multispectral Airborne Laser Scanning （ALS） data to classify 24 common urban roadside tree species in Espoo， Finland. We utilized tree crown structure information， intensity features， and spectral information for classification. 8 different machine learning algorithms were used in our study and Extra trees （ET） performed best with an overall accuracy of 71.7% using multispectral LiDAR data， highlighting that combining structural and spectral information in a single frame could enhance classification accuracy. In the future， we will focus on identifying the most important features in species classification and finding algorithms with higher efficiency and accuracy.

• Detection and quantification of water / ice in typical lunar minerals using Raman spectroscopy

  WEN Dao-Yuan-Tian, Zhao Hai-Ting, LIU Xiang-Feng, XU Wei-Ming, XU Xue-Sen, LEI Xin-Rui, SHU Rong

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (115) HTML (0) PDF (1.25 MKB)(51)

  Abstract:

  The water in lunar materials can promote the evolution of lunar geology and environment and provide the necessary conditions for the utilization of lunar resource. Owing to the low resolution of lunar remote sensing methods， it is difficult to obtain direct evidence of water / ice or determine its form of occurrence. Laser Raman spectroscopy can obtain fingerprint information of minerals and water bodies without the need for illumination， sample pretreatment， and non-destructive， providing direct and favorable information regarding the type， distribution range， and content of lunar materials. In this study， Raman spectroscopy was used to detect the water-containing characteristics of typical lunar rocks/minerals and forms such as adsorbed water， ice， crystalline water， and hydroxyl-structured water， and quantitatively analyze the water content. First， a 532 nm laser micro-Raman spectroscopy was used to identify and analyze the water-containing signals of typical lunar minerals and various forms of water in lunar soil simulants. Second， the detection limits of adsorbed water， crystalline water， and hydroxyl-structured water in lunar soil simulants were examined and analyzed， along with the patterns between their content and signal intensity. Finaly， linear regression （LR）， ridge regression （RR）， and partial least squares regression （PLSR） were employed for quantitatively analyze of the contents of three forms of water in the lunar soil simulants. The results show that （1） the characteristic spectral peaks of the four forms of water in the lunar soil simulants can be clearly identified. The peak distribution regions of the lunar soil simulants components and water bodies are located at 100-1700 cm^-1 and 2600-3900 cm^-1， respectively. The characteristic spectral peaks of water are manifested as a combination of broad envelope peaks of hydrogen-bonded OH and sharp peaks of non-hydrogen-bonded OH stretching vibrations in varying proportions. （2） Detection limits of adsorbed water， crystalline water （MgSO₄·7H₂O）， and hydroxyl water （Al₂Si₂O₅（OH）₄） in the lunar soil simulants are 1.3 wt%， 0.8 wt%， and 0.3 wt%， respectively. （3） A linear relationship exists between the intensity of water-containing peaks and the water content in the lunar soil simulants， with root mean square errors of 1.75 wt%， 1.16 wt%， and 1.19 wt% obtained through LR， RR， and PLSR.

Infrared Physics, Materials and Devices

• Simulation design of short-wave infrared heterogeneous phototransistor for weak light detection

  LIAO Ke-Cai, HUANG Min, WANG Nan, LIANG Zhao-Ming, ZHOU Yi, CHEN Jian-Xin

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (75) HTML (0) PDF (1.21 MKB)(44)

  Abstract:

  The sensitivity of the detector is the core technical indicator of the infrared detector. Short-wave infrared detector has low dark current and the sensitivity will be limited by the inherent read-out circuit noise of the detection system. Therefore， it is an effective way to further enhance the sensitivity by introducing internal gain into the detector. Heterogeneous phototransistor takes advantages of high gain， low operating bias， and low excess noise， which provides novel approach for high-sensitive detection. This paper mainly focuses on the simulation design of InGaAs/GaAsSb type-II superlattice short-wave infrared phototransistor， and studies the dependence of the device size on the optoelectronic characteristics. The results show that a higher gain， a lower dark current， and a faster response can be achieved by a smaller base size. Based on the optimization design of size structure， a sensitivity with a noise equivalent photon lower than 10 can be achieved， which provides a new technical approach to achieve high-sensitive heterogeneous phototransistor detector.

Interdisciplinary Research on Infrared Science

• Infrared remote sensing image super-resolution network by integration of dense connection and multi-attention mechanism

  XU Xin-hao, WANG Jun, WANG Feng, SUN Sheng-li

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (54) HTML (0) PDF (1.72 MKB)(64)

  Abstract:

  Space-borne infrared remote sensing images have crucial application value in the fields of environmental monitoring and military reconnaissance. Nonetheless， due to limitations in technologies， atmospheric disturbances， and sensor noise， these images suffer from insufficient resolution and blurred texture details， severely restricting the accuracy of subsequent analysis and processing. To address these issues， a new super-resolution generative adversarial network model is proposed. This model integrates dense connections with the Swin Transformer architecture to achieve effective cross-layer feature transmission and contextual information utilization while enhancing the model"s global feature extraction capabilities. Furthermore， we improve the traditional residual connections with multi-scale channel attention-based feature fusion， allowing the network to more flexibly integrate multi-scale features， thereby enhancing the quality and efficiency of feature fusion. A combined loss function is constructed to comprehensively optimize the performance of the generator. Comparative tests on different datasets demonstrate significant improvements with the proposed algorithm. Additionally， the super-resolved images exhibit higher performance in downstream tasks such as object detection， confirming the effectiveness and application potential of the algorithm in space-borne infrared remote sensing image super-resolution.

• BDMFuse: Multi-Scale Network Fusion for Infrared and Visible Images Based on Base and Detail Features

  Si Haiping, Zhao Wenrui, Li Tingting, Li Feitao, Fernando Bacao, Sun Changxia, Li Yanling

  DOI:

  Abstract: (89) HTML (0) PDF (1.93 MKB)(45)

  Abstract:

  The fusion of infrared and visible images should emphasize the salient targets in the infrared image while preserving the textural details of the visible image. To meet these requirements, an autoencoder-based method for infrared and visible image fusion is proposed. The encoder consists of a base encoder and a detail encoder, designed according to the optimization objective, to extract low-frequency and high-frequency information from the image. This extraction may lead to some information not being captured, so a compensation encoder is proposed to supplement the missing information. Multi-scale decomposition is also employed to extract image features more comprehensively. The decoder combines low-frequency, high-frequency and supplementary information to obtain multi-scale features. Subsequently, the attention strategy and Fusion module are introduced to perform multi-scale fusion for image reconstruction. Experimental results on three datasets show that the fused images generated by this network effectively retain salient targets while being more consistent with human visual perception.

红外物理与材料器件

• Tidal flats extraction in the coastal zone based on time-series Sentinel-2 imagery and near-infrared tidal flats indices

  ZHOU Ru-Jia, XIA Qing, ZHENG Qiong, ZHU Li-Hong, LI Jian-Hua, LI Bin, SONG Jia

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (89) HTML (0) PDF (2.78 MKB)(50)

  Abstract:

  When extracting coastal zone tidal flats using remote sensing transient images, the influence of tides greatly limits the accuracy of tidal flat spatial distribution extraction. With the purpose of weakening the influence of tides, a method of extracting coastal zone tidal flats by combining time-series Sentinel-2 images and tidal flat index is proposed. First, based on the Sentinel-2 time-series image data, we use the quantize synthesis method to generate high- and low-tide images, and then analyze the spectral reluctance characteristics of different land classes on the high- and low-tide images. A NIR-band tidal flat extraction index that excludes the interference of the tidal transient is constructed. Secondly, the image spectral information and the tidal flat extraction index are input into a machine learning algorithm to realize fast and efficient extraction of the tidal flat. In addition, the study discusses the separability of the tidal flats index and the generalizability of the methodology. The results show that the tidal flat's extraction index constructed in this research had a good separability for tidal flats, the overall accuracy of tidal flats extraction was 93.02%, the Kappa coefficient was 0.86, and the proposed method has good applicability to remote sensing images containing near-infrared bands. This method can realize automatic and rapid tidal flat extraction, and provide data support for the sustainable management and protection of coastal zone resources.

Millimeter Waves and Terahertz Technology

• A High Output Power 340GHz Balanced Frequency Doubler Design Based on Linear Optimization Method

  Liu Zhicheng, Zhou Jingtao, Meng Jin, Wei Haomiao, Yang Chengyue, Su Yongbo, Jin Zhi, Jia Rui

  DOI:

  Abstract: (104) HTML (0) PDF (1.84 MKB)(37)

  Abstract:

  In this paper， a linear optimization method（LOM） for the design of terahertz circuits is presented， aimed at enhancing simulation efficacy and reducing the time of the circuit design workflow. This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations. By optimizing the linear matching circuit with the optimal embedding impedance， the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit， substantially increasing the speed of simulations. The design of on-chip linear matching circuits adopts a modular circuit design strategy， incorporating fixed load resistors to simplify the matching challenge. Utilizing this approach， a 340GHz frequency doubler was developed and measured. The results demonstrate that， across a bandwidth of 330GHz to 342GHz， the efficiency of the doubler remains above 10%， with an input power ranging from 98mW to 141mW and an output power exceeding 13mW. Notably， at an input power of 141mW， a peak output power of 21.8mW was achieved at 334GHz， corresponding to an efficiency of 15.8%.

Infrared Physics, Materials and Devices

• Study on the preparation and spectroscopic ellipsometry of MoTe₂ quantum dot films

  LI Guo-Bin, HU Kun, ZHANG Tai-Wei, YANG Ao, XIA Yi-Ping, LI Xue-Ming, TANG Li-Bin, YANG Pei-Zhi, WANG Shan-Li, CHEN Sheng-Di, YANG Li, ZHANG Yan

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (58) HTML (0) PDF (2.73 MKB)(39)

  Abstract:

  The preparation of quantum dot thin films and the accurate determination of optical constants are particularly important in the development and application of their optoelectronic fields. At present， the optical constants of MoTe₂ single-crystal films prepared by mechanical exfoliation and chemical vapor deposition are relatively mature. However， the optical constants of 2H-MoTe₂ quantum dot films are rarely reported. 2H-MoTe₂ quantum dots were prepared by ultrasonic assisted liquid phase exfoliation， and two sizes of 2H-MoTe₂ quantum dots were prepared by changing the type of solvent and ultrasonic order. The optical constants such as refractive index， extinction coefficient and dielectric constant of quantum dot films of two sizes were studied by B-spline model and Tauc-Lorentz model using ellipsometry. The results show that the two sizes of 2H-MoTe₂ quantum dots have similar refractive index， extinction coefficient and a wider spectral absorption in the visible to near infrared band. And compared with MoTe₂ bulk material， it has a lower dielectric constant.

红外物理与材料器件

• Simulation and Evaluation of Mid-Infrared Sea Surface Sun Glint Directional Radiation

  ZHANG Zhen-Wu, WANG Ning, MA Ling-Ling, ZHANG Bei-Bei, ZHAO Yong-Guang, LI Wan

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (90) HTML (0) PDF (1.68 MKB)(41)

  Abstract:

  The energy received in the mid-infrared (MIR) band at the sensor's aperture includes both reflected solar energy and the emitted energy from Earth's surface. Typically, the reflected solar energy in this band is weak; however, under certain conditions, such as in sun glint regions over the sea surface, the reflected solar energy detected by the MIR channel can be substantial. Currently, the application of sun glints physical models in the MIR band is not well-understood. This study investigates the accuracy of applying different visible light and shortwave infrared sun glint models to the MIR band. The paper selects three models: Breon-Henriot, Ebuchi-Kizu, and Wu, and evaluates the sensitivity of each sun glint model. Subsequently, using four selected MODIS sun glint images as data sources, and combining them with ERA5 reanalysis data matched to satellite data for atmospheric parameter calculations, the solar radiation intensity reflected by the sea surface is computed using the three models. The accuracy of each model is then further validated with an MIR radiation transfer model. The results show that the Breon-Henriot model generally performs best in terms of correlation coefficient and root-mean-square error compared to MODIS measurements. These findings not only extend the application range of sun glint models in the MIR band but also enhance the MIR forward modeling system, providing new theoretical support for MIR radiation transfer and improving the effectiveness and accuracy of MIR remote sensing products in climate change monitoring and sea surface temperature dynamic analysis.

• Waveform frequency domain matching-based positioning method for satellite-borne LIDAR footprints

  ZHOU Si-Han, ZHAO Pu-Fan, HAN Qi-Jin, LUAN Chao, YANG Jian, WANG Heng, MA Yue, ZHOU Hui, LI Song

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (62) HTML (0) PDF (1.65 MKB)(48)

  Abstract:

  The laser altimeter onboard China's Gaofen series satellites is primarily used to provide elevation control points for imagery. During satellite operations, environmental variations can induce laser pointing offsets, which in turn increase the positioning errors of the footprints, thereby directly reducing the elevation accuracy of the control points. This issue is particularly pronounced in complex mountainous terrains. To enhance the reliability of laser altimeter observations from satellites in such regions, this paper proposed a new laser footprint positioning method based on waveform frequency domain matching. This method utilizes high-precision terrain data for waveform simulation and determines the position of the laser footprint by calculating the correlation between the simulated waveform and the waveform received by China's Gaofen series satellite in the frequency domain. Additionally, systematic deviations in laser pointing are derived from the joint computational results of multi-footprint frequency domain matching. Experiments were conducted using in three regions: central Montana, western Wyoming, and eastern Utah in the United States. The results indicate that the standard deviations of footprint planar offset distances, planar true north pinch angles, and equivalent laser pointing deviation angles obtained with this method are all superior to those achieved with the time-domain waveform matching method. The findings underscore the advantages of frequency-domain waveform matching in achieving high-precision footprint localization, thereby providing a robust foundation for enhancing the utility of satellite laser altimeter observations in challenging environments and facilitating the correction of laser altimeter pointing errors.

Interdisciplinary Research on Infrared Science

• Analysis of Infrared Polarization Characteristics and Modeling of Operating Distance on Aerostat Platform in Sea Fog

  YE Min-Rui, CUI Wen-Nan, HUANG Xia-Yang, Zhang Tao

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (43) HTML (0) PDF (977.50 KKB)(47)

  Abstract:

  The study aims to reveal the detection advantages of infrared polarization imaging systems deployed on aerostat platforms in sea fog conditions. Firstly, based on the polarization bidirectional reflection distribution function, this research analyzes how polarization characteristics vary with observation angles, demonstrating the applicability of infrared polarization in oblique viewing from aerostats. Secondly, by using the Monte-Carlo method and MRTD model, the study develops a model to determine the maximum operating distance of infrared polarization imaging systems. This model verifies the superiority of infrared polarization imaging over infrared intensity imaging in terms of maintaining features and detection distance under sea fog conditions. The results provide theoretical analysis and simulation evidence supporting the deployment of infrared polarization technology on aerostat platforms.

红外物理与材料器件

• Study on Correlation of Thermal Model to in-Orbit Data for Infrared Optical Payloads on FY-3E/HIRAS-II

  LI Yu-Han, YANG Bao-Yu, ZHANG Qiang, GUO Zhi-Peng, WU Yi-Nong, TANG Xiao, LI Shang-Ju

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (28) HTML (0) PDF (1.60 MKB)(39)

  Abstract:

  The Infrared Hyperspectral Atmospheric Sounder II (HIRAS-II) is the key equipment on Funyun-3E (FY-3E) satellite, which can realize vertical atmospheric detection, featuring hyper spectral, high sensitivity and high precision. To ensure its accuracy of detection, it is necessary to correlate their thermal models to in-orbit data. In this work, an investigation of intelligent correlation method named Intelligent Correlation Platform for Thermal Model (ICP-TM) was established, the advanced Kriging surrogate model and efficient adaptive region optimization algorithm were introduced. After the correlation with this method for FY-3E/HIRAS-II, the results indicate that compared with the data in orbit, the error of the thermal model has decreased from 5 K to within ±1 K in cold case (10℃). Then, the correlated model is validated in hot case (20℃), and the correlated model exhibits good universality. This correlation precision is also much superiors to the general ones like 3 K in other similar literature. Furthermore, the process is finished in 8 days using ICP-TM, the efficiency is much better than 3 months based on manual. The results show that the proposed approach significantly enhances the accuracy and efficiency of thermal model, this contributes to the precise thermal control of subsequent infrared optical payloads.

Infrared Optoelectronic System and Application Technology

• Design and preparation of LWDM AWG for 1.6Tbps and above data center

  HUANG Song, CUI Peng-Wei, WANG Yue, WANG Liang-Liang, ZHANG Jia-Shun, MA Jun-Chi, ZHANG Chun-Xue, GUO Li-Yong, YANG Han-Ming, WU Yuan-Da, AN Jun-Ming, SONG Ze-Guo

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (37) HTML (0) PDF (2.53 MKB)(48)

  Abstract:

  A 16-channel arrayed waveguide grating （AWG） with an 800 GHz channel spacing in the O-band has been developed and fabricated based on silica planar lightwave circuit （PLC） technology. By extending the wavelength allocation from 8 channels to 16 channels as specified in IEEE 802.3bs， we increased the number of channels and boosted transmission capacity to meet the 1.6 Tbps and higher-speed signal transmission requirements for future data centers. Through optimizing the AWG structure， it has achieved insertion loss （IL） better than -1.61 dB， loss uniformity below 0.35 dB， polarization-dependent loss （PDL） below 0.35 dB， adjacent channel crosstalk under -20.05 dB， ripple less than 0.75 dB， center wavelength offset under 0.22 nm and 1 dB bandwidth exceeding 2.88 nm. The AWG has been successfully measured to transmit 53 Gbaud 4-level pulse amplitude modulation （PAM4） signal per channel and the total transmission speed can reach 1.6Tbps and above.

Interdisciplinary Research on Infrared Science

• An Improved Template Matching Algorithm for Infrared Cross-Target Center Positioning Based on Self-Constructed Convolution Kernels

  Yuan Di-jian, Xu Xin-ke, Liu Tong, Wang Jin-wen, Du Yu

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (63) HTML (0) PDF (1.18 MKB)(69)

  Abstract:

  Target center positioning is a critical technology in the calibration process of infrared thermal imagers. Given the relatively complex morphology of target images， we propose a center positioning algorithm based on improved template matching with self-constructed convolution kernels. The algorithm first constructs a normalized template with target image features and performs matching operations on downsampled and preprocessed target images to obtain coarse positioning results. Based on the coarse positioning center， the original image undergoes ROI fine matching， and further correction is achieved through a subpixel subdivision algorithm， ultimately determining the precise target center position. This algorithm effectively detects target images with blurring and indistinct edge features， avoiding interference from blurring， occlusion， complex backgrounds， or indistinct features. It demonstrates good robustness， accurately positions the target center， and operates at high speed. Compared to traditional template matching methods like CCORR， NCC， and Hough transform， it offers significant improvements and meets the positioning requirements in the automatic calibration process of infrared thermal imagers.

• Sparsity and Self-Similarity Priors Guided Deep Learning for Blind Image Super-Resolution

  GE Sun-Yi, LUO Xiao-Wei, FENG Shi-Yang, WANG Bin

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (74) HTML (0) PDF (1.14 MKB)(45)

  Abstract:

  The existing deep learning-based image blind super-resolution algorithms only utilize neural networks to learn the end-to-end mapping from low-resolution (LR) images to high-resolution (HR) images, only allowing the network to implicitly learn image priors, resulting in algorithms that still produce blurry super-resolution results. To address the above issues, a deep learning image blind super-resolution algorithm guided by sparsity and self-similarity priors is proposed. Initially, for various LR image inputs, a dynamic linear kernel estimation module is employed to effectively estimate the corresponding blur kernels; Subsequently, a deep unfolding deconvolution filtering module based on the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) is utilized to explicitly model the sparsity prior of signal, achieving deconvolution restoration of the degraded images; Finally, a dual-path multi-scale large receptive field restoration module leverages the self-similarity prior of images for super-resolution recovery. The experimental results indicate that, compared to existing methods, the proposed algorithm achieves a peak signal-to-noise ratio (PSNR) of 31.66 and a structural similarity index (SSIM) of 0.8725 on the publicly available Gaussian8 dataset, and attains a PSNR of 29.08 and an SSIM of 0.8007 on the DIV2KRK dataset. The images restored by the proposed algorithm not only exhibit the highest restoration metrics but also superior visual quality.

红外物理与材料器件

• Infrared UAV Detection Based on Multi-Channel Interactive Attention Mechanism and Edge Contour Enhancement

  NIE Su-Zhen, CAO Jie, ZHUANG Xu-Ye, HAO Qun

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (37) HTML (0) PDF (1.97 MKB)(53)

  Abstract:

  UAVs have a wide range of applications in agriculture， logistics， rescue and disaster relief because of their compactness， lightness and flexibility. However， if they are used improperly or mismanaged， they may not only cause personal privacy leakage and property loss， but also pose a threat to public safety and even military security. Therefore， real-time and accurate detection and warning of UAVs in the airspace plays an important role. In this regard， a multi-channel interactive attention and edge contour enhancement （MCIAECE） method for infrared UAV detection is proposed. Firstly， the shallow and deep features of the infrared image are extracted by constructing a multi-channel consisting of a multi-channel interactive attention mechanism module and an edge contour enhancement module， after which the attention mechanism enhances the target features while the edge contour enhancement obtains more detailed information. Then the extracted features of each layer are fused and enhanced using the multilevel feature fusion module to obtain the detection results. The experimental results show that better results can be achieved with multi-channel interactive attention and edge contour enhancement on all three datasets. Among them， the best results are obtained on the NUDT-SIRST infrared dataset， with the detection probability and intersection and concurrency ratio of 98.83% and 85.11% respectively compared with the baseline network， and the effect is significant in the edge contour restoration of the target compared with other methods.

Infrared Physics, Materials and Devices

• Research on the Punch-through Phenomenon of Separate Absorption， Charge， and Multiplication Avalanche Photodetectors

  LI Chong, MA Zi-Yi, YANG Shuai, LIU Yue-Wen, WANG Jia-Xuan, LIU Yun-Fei, DONG Yu-Sen, LI Zi-Qian, LIU Dian-Bo

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (34) HTML (0) PDF (1.38 MKB)(42)

  Abstract:

  In this paper, the punch-through phenomenon was studied, based on a fabricated separate absorption, charge, and multiplication avalanche photodetector (SACM APD). The spectral response, capacitance characteristics, and I-V characteristics at different operating temperatures of the APD were measured and analyzed. Meanwhile, the device performance before and after the punch-through phenomenon were compared, and the model of the electric field region formed by external voltage was analyzed, based on the measurement results and the simulated the electric field and energy band distributions by the SILVACO. When the ion implantation energy of the charge layer was 580KeV, the simulated device has a punch-through voltage of -30V and a capacitance reduction of one-third before punch-through. Then, a Si SACM APD was prepared based on CMOS process. The punch-through voltage of the device was -30V and the capacitance was reduced to 1/3@1MHz before punch-through, which exactly match the simulation results. Moreover, the photocurrent after punch-through increases to 2.18 times of the before value at 808 nm. The peak responsivity increases from 0.171 A/W@590 nm to 0.377 A/W@820 nm.

• A near-infrared all-fiber mode monitor based on the mini-two-path Mach-Zehnder interferometer

  ZHU Xiao-Jun, LIU Yu, WU Yue, ZHUANG Hao-Ran, SUN Dan, SHI Yue-Chun, CAO Juan, YANG Yong-Jie

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (57) HTML (0) PDF (1.20 MKB)(38)

  Abstract:

  A novel near-infrared all-fiber mode monitor based on a mini-two-path Mach-Zehnder interferometer (MTP-MZI) is proposed. The MTP-MZI mode monitor is created by fusing a section of no-core fiber (NCF) and a single-mode fiber (SMF) together with an optical fiber fusion splicer, establishing two distinct centimeter-level optical transmission paths. Since the high-order modes in NCF transmit near-infrared light more sensitively to curvature-induced energy leakage than the fundamental mode in SMF, the near-infrared high-order mode light leaks out of NCF when the curvature changes, causing the MTP-MZI transmission spectrum to change. By analyzing the relationship between the curvature, transmission spectrum, and spatial frequency spectrum, the modes involved in the interference can be studied, thereby revealing the mode transmission characteristics of near-infrared light in optical fibers. In the verification experiments, higher-order modes were excited by inserting a novel hollow-core fiber (HCF) into the MTP-MZI. When the curvature of the MTP-MZI changes, the near-infrared light high-order mode introduced into the device leaks out, causing the transmission spectrum to return to its original state before bending and before the HCF was spliced. The experimental results demonstrate that the MTP-MZI mode monitor can monitor the fiber modes introduced from the external environment, providing both theoretical and experimental foundations for near-infrared all-fiber mode monitoring in optical information systems.

Interdisciplinary Research on Infrared Science

• Structural Design of a Wide-ridge Mid-wave Infrared Quantum Cascade Laser Based on a Supersymmetric Waveguide

  DU Shu-Hao, ZHENG Xian-Tong, JIA Han, CUI Jin-Tao, ZHANG Shi-Ya, FENG Yu-Lin, LIU Yuan, LIU ming, ZHANG Dong-Liang

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (56) HTML (0) PDF (1004.59 KKB)(47)

  Abstract:

  In the process of power scaling large-area quantum cascade lasers （QCLs）， challenges such as degradation of beam quality and emission of multilobe far-field modes are frequently encountered. These issues become particularly pronounced with an increase in ridge width， resulting in multimode problems. To tackle this， an innovative multiridge waveguide structure based on the principle of supersymmetry （SUSY） was proposed. This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side. The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design， and the optical loss of the auxiliary waveguides suppresses these modes， thereby achieving fundamental mode lasing of the wider main waveguide. This paper employs the finite difference eigenmode （FDE） method to perform detailed structural modelling and simulation optimization of the 4.6 μm wavelength quantum cascade laser， successfully achieving a single transverse mode QCL with a ridge width of 10 μm. In comparison to the traditional single-mode QCL（with a ridge width at about 5 μm）， the MRW structure has the potential to increase the gain area of the laser by 100%. This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers， which is of considerable significance.

Millimeter Waves and Terahertz Technology

• Performance analysis of electro-optic sampling detection technique with thin GaSe crystal in mid-infrared band

  DU Hai-Wei, WANG Jing-Yi, LI Qiang-Shuang, SUN Chang-Ming

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (45) HTML (0) PDF (646.82 KKB)(31)

  Abstract:

  Electro-optic sampling （EOS） detection technique has been widely used in the terahertz science and technology， and it also can measure the field time waveform of the few-cycle laser pulse. Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse. Here， we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle laser pulse. The shift of the central frequency and change of the bandwidth induced by the EOS detection are calculated， and then the pulse distortions induced in this detection process are discussed. It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth. These changings decrease when the laser wavelength increase from 2 μm to 10 μm. This work can help to estimate the performance of the EOS detection technique in the mid-infrared band and offer a reference for the related experiment as well.

Application of Optical-Biomedical Fusion and Imaging Technology

• Alignment-Optimised Coaxial Visible-NIR-II Dual-Channel Surgical Navigation System and Its Clinical Application in Blood-Supply Assessment

  Zhang Yu-Huang, Liu Xiao-Long, Sun Si-Ying, Fan Xiao-Xiao, Lin Hui, Qian Jun

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (36) HTML (0) PDF (1.64 MKB)(90)

  Abstract:

  Fluorescence imaging in the second near-infrared window (NIR-II, 900-1880 nm) offers high signal-to-background ratio (SBR), enhanced definition, and superior tissue penetration, making it ideal for real-time surgical navigation. However, with single-channel imaging, surgeons must frequently switch between the surgical field and the NIR-II images on the monitor. To address this issue, a coaxial dual-channel imaging system that combines visible light and 1100 nm long-pass (1100LP) fluorescence was developed. The system features a customized coaxial dual-channel lens with optimized distortion, achieving precise alignment with an error of less than ±0.15 mm. Additionally, the shared focusing mechanism simplifies operation. Using FDA-approved indocyanine green (ICG), the system was successfully applied in dual-channel guided rat lymph node excision, and blood supply assessment of reconstructed human flap. This approach enhances surgical precision, improves operational efficiency, and provides a valuable reference for further clinical translation of NIR-II fluorescence imaging.

红外物理与材料器件

• Multi-physics coupling-based multi-parameter joint optimization technique for aerial target infrared detection

  DING Xiang, QIAO Kai

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (55) HTML (0) PDF (1.49 MKB)(33)

  Abstract:

  One of the key areas of advancement in space-based infrared sensing is the high-sensitivity detection of small and weak targets. A major innovation in this regard is the design of the infrared detection system indicator, which is influenced by the characteristics of the target background radiation. The effectiveness of space-based infrared detection is significantly challenged by airborne targets, especially civil aircraft. These targets are active in the upper troposphere and lower stratosphere. They exhibit weak and variable radiation characteristics due to complex background clutter and atmospheric attenuation. Aiming to address this issue, this paper proposes a multi-parameter joint optimization method for an airborne target infrared detection system based on the coupling of the multiple physical effects. Firstly, the initial optimization of the target detection spectral band in the sky is completed based on the spectral radiation characteristics of the target, the background, and the spectral atmospheric transmittance change characteristics of the target-sky-based detection platform. Subsequently, the detection sensitivity requirements are proposed. Then, a system parameter optimization method is established with the target motion speed limit, earth background limit, and detection sensitivity as the three major boundaries. This method facilitates the creation of an infrared detection index system for air targets.

毫米波与太赫兹技术

• Research on low-power consumption， high heat dissipation efficiency terahertz quantum cascade laser

  TAN Cheng, YAN Chuan-Feng, ZANG Shan-Zhi, WANG Kai, GAN Liang-Hua, CAO Chen-Tao, CHEN Bing-Qi, CHEN Hong-Tai, ZHANG Yue-Heng, FANG Yu-Long, XU Gang-Yi

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (49) HTML (0) PDF (1.72 MKB)(45)

  Abstract:

  A single-mode terahertz quantum cascade laser （THz-QCL） with a two-dimensional patch antenna array as a resonant cavity is proposed and realized. The active region of each patch antenna is sandwiched between two metal layers， exhibiting full-scale subwavelength characteristics and exciting a vertical electric quadrupole mode with low radiation loss. The inter-antenna coupling within the array effectively suppresses electromagnetic leakage in the plane， allowing for a high-quality factor and low threshold current density even with only a few antennas in the array. As a result， the laser"s power consumption is reduced to 950 mW. Moreover， the discrete antenna array design provides a larger heat dissipation area compared to the heat-generating area， and with the lateral heat dissipation channels offered by the unpumped regions， the thermal resistance per unit area is as low as 5.6 mK/W/cm². By significantly reducing power consumption and enhancing heat dissipation efficiency， the laser achieves a lasing frequency of 3.18 THz， a side-mode suppression ratio （SMSR） of 19.5 dB， and a beam divergence angle of 35°×35°. It operates continuously at 3.14 mW at 20 K， with a maximum continuous operation temperature of 90 K， notably higher than that of Fabry-Pérot cavity lasers made from the same material. This work provides a novel approach to improve the continuous operating temperature of THz-QCLs.

Interdisciplinary Research on Infrared Science

• Infrared small target detection method based on nonconvex tensor Tuck decomposition with factor prior

  YANG Jun-Gang, LIU Ting, LIU Yong-Xian, LI Bo-Yang, WANG Ying-Qian, SHENG Wei-Dong, AN Wei

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (116) HTML (0) PDF (2.05 MKB)(49)

  Abstract:

  Low-rank and sparse decomposition method （LRSD） has been widely concerned in the field of infrared small target detection because of its good detection performance. However， existing LRSD-based methods still face the problems of low detection performance and slow detection speed in complex scenes. Although existing low-rank Tuck decomposition methods achieve satisfactory detection performance in complex scenes， they need to define ranks in advance according to experience， and too large or too small the estimated ranks will lead to missed detection or false alarms. Meanwhile， the size of rank is different in different scenes. This means that they are not suitable for real-world scenes. To solve this problem， this paper uses non-convex rank approach norm to constrain latent factors of low-rank Tucker decomposition， which avoids setting ranks in advance according to experience and improves the robustness of the algorithm in different scenes. Meanwhile， an symmetric GaussSeidel （sGS） based alternating direction method of multipliers algorithm （sGSADMM） is designed to solve the proposed method. Different from ADMM， the sGSADMM algorithm can use more structural information to obtain higher accuracy. Extensive experiment results show that the proposed method is superior to other advanced algorithms in detection performance and background suppression.

Infrared Physics, Materials and Devices

• The Research on Polarization-tunable Terahertz GaAs Photoconductive Antenna array

  Dong Chengang, Shi Wei, Han Xiaowei, Wang Zhiquan, Wang Xin, Zhang Xiuxing

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (120) HTML (0) PDF (1.61 MKB)(359)

  Abstract:

  As an important emitter of terahertz radiation, the traditional antenna has limited flexibility due to its fixed polarization state. In response to this issue, we have designed and studied a polarization-adjustable four-element terahertz gallium arsenide photoconductive antenna array, aiming to enhance its versatility and applicability in various applications. By precisely controlling the excitation of each element, the antenna array can achieve precise control of linearly and circularly polarized terahertz waves through in-phase unequal amplitude excitation and phase difference excitation. The results show that with in-phase unequal amplitude excitation, flexible control of linearly polarized terahertz waves within a 360-degree range can be achieved. With a 90-degree phase difference excitation, circularly polarized terahertz waves are generated, with a -10 dB impedance bandwidth range of 0.057 THz to 1.013 THz and a relative bandwidth of 178.69%. The axial ratio bandwidth range is 0.815 THz to 0.947 THz, with a relative bandwidth of 14.98%.

• The study of hyperspectral remote sensing air traffic control monitoring based on contrails cloud proposal

  Yang Lifeng, Feng Yanqing, WangJianyu

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (79) HTML (0) PDF (2.49 MKB)(318)

  Abstract:

  To address the issues of low detection rate and high false alarm rate caused by complex background during sub-pixel aerial aircraft detection in hyperspectral remote sensing image, an aerial aircraft detection method was proposed based on contrails cloud proposal. Firstly, a hyperspectral semantic segmentation model was used to search for the contrails cloud, and ROIs of aircraft were proposed to reduce invalid search ranges and suppress false alarms based on the contrails cloud; Secondly, an endmember extraction algorithm based on dictionary learning and semi-blind non-negative matrix factorization was proposed to improve the accuracy of aircraft endmember extraction for hyperspectral subpixels; Finally, verification experiments were carried out on the hyperspectral remote sensing image dataset of gaofen-5 satellite, and the results demonstrated that the algorithm proposed in this paper can effectively suppress false alarms in complex scenes, and significantly improve the detection rate and detection accuracy of sub-pixel aerial vehicles.

• Infrared small target detection algorithm via Partial Sum of the Tensor Nuclear Norm and direction residual weighting

  SUN Bin, XIA Xing-Ling, FU Rong-Guo, SHI Liang

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (97) HTML (0) PDF (1.86 MKB)(205)

  Abstract:

  Aiming at the problem that infrared small target detection faces low contrast between the background and the target and insufficient noise suppression ability under the complex cloud background, an infrared small target detection method based on the tensor nuclear norm and direction residual weighting is proposed. Based on converting the infrared image into an infrared patch tensor model, from the perspective of the low-rank nature of the background tensor, and taking advantage of the difference in contrast between the background and the target in different directions, we design a double-neighborhood local contrast based on direction residual weighting method (DNLCDRW) combined with the partial sum of tensor nuclear norm (PSTNN) to achieve effective background suppression and recovery of infrared small targets. Experiments show that the algorithm is effective in suppressing the background and improving the detection ability of the target.

Infrared Optoelectronic System and Application Technology

• Research progress on infrared temperature measurement for low emissivity object

  HUANG Shan-Jie, ZHAO Jin-Song, WANG Ling-Xue, SONG Teng-Fei, XU Fang-Yu, CAI Yi

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (100) HTML (0) PDF (1.43 MKB)(337)

  Abstract:

  Smooth objects such as metals， optical mirrors， and silicon wafers generally have extremely low emissivity and high reflectivity， and are called low emissivity objects.The extremely weak radiation from low emissivity objects will be submerged by the environmental radiation reflected from their surface. Infrared temperature measurement of low emissivity objects has always been a challenge in the field of infrared temperature measurement. Due to the continuously growing demand for non-contact temperature measurement of low emissivity objects in fields such as metal smelting， solar telescope thermal control， and semiconductor production， a large number of infrared temperature measurement methods for low emissivity objects have been proposed. First， this paper elaborates on the difficulties of the infrared temperature measurement of low emissivity objects and summarizes the temperature measurement methods currently used for low emissivity objects into five categories. Then， the basic principles and technical routes of each temperature measurement method were summarized， and the advantages and disadvantages of each temperature measurement method were analyzed in detail. Finally， the possible development directions of temperature measurement for low emissivity objects were discussed.

Infrared Physics, Materials and Devices

• Study of time and frequency domain characteristics of a quasi-continuous 2 μm thulium-doped fiber laser

  MEI Xue-Han, CHEN Xiang, XU Gang, YANG Yuan-Zhong, ZHANG Zhong, LEI Cheng, LI Sheng, WANG Xing-Huan, WANG Du

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (144) HTML (0) PDF (947.47 KKB)(473)

  Abstract:

  Lasers near the wavelength of 2 μm are located in the atmospheric transmission window and the strong absorption peak of water， and have important applications in medicine， LIDAR， material processing， and as pump sources for mid-infrared lasers. The thulium-doped fiber laser （TDFL） stands out as a critical light source capable of delivering high power outputs at this wavelength. In this paper， to address the problems of relaxation oscillation and inter-modal four-wave mixing in quasi-continuous wave （QCW） TDFL， the time and frequency-domain output characteristics of the laser are optimized by increasing the bias current， optimizing the length of the gain fiber， and changing the diameter of the fiber coiling， etc. The effects of different gain fiber structures on the fiber transmission modes are also investigated. The developed QCW-TDFL achieves a peak power of 894 W and an average power of 89.4 W at a central wavelength of 1939.2 nm with a pulse width of 100 μs， a repetition frequency of 1 kHz and a duty cycle of 10%， and obtains stable and controllable pulse output waveforms and spectral characteristics.

Interdisciplinary Research on Infrared Science

• A lightweight dark object detection network on infrared images

  Li Zhaoxu, Xu Qingyu, An Wei, He Xu, Guo Gaowei, Li Miao, Ling Qiang, Wang Longguang, Xiao Chao, Lin Zaiping

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (230) HTML (0) PDF (1.24 MKB)(403)

  Abstract:

  Small target detection has been a classic research topic in the field of infrared image processing, and the objects are usually brighter than the local background. However, in some scenarios, the target brightness may be lower than the background brightness. For example, the civil airplanes usually have low-temperature skin when cruising, appearing as dark points on medium spatial resolution thermal infrared satellite images. There are few features of these objects, so the current detection networks are redundant. Hence, authors proposed a lightweight dark object detection network, AirFormer. It only has 37.1K parameters and 46.2M floating-point operations on a 256×256 image. Considering the lack of infrared dark object detection dataset, authors analyzed the characteristics of airplanes on thermal infrared satellite images, and then developed a simulated flying aircraft detection dataset called IRAir. AirFormer achieves 71.0% at recall and 82.6% at detection precision on the IRAir dataset. In addition, after training on simulated data, AirFormer has achieved detection of real flying airplanes on the thermal infrared satellite images.

Infrared Physics, Materials and Devices

• The Research on Aircraft Altitude Estimate Method Based on Multispectral Feature Matching in Thermal Infrared

  Yang Lifeng, Chen Zhuo, Chen Fansheng, WangJianyu

  DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001

  Abstract: (138) HTML (0) PDF (1.36 MKB)(247)

  Abstract:

  The acquisition of aircraft altitude information is crucial for aviation safety and traffic control applications. Infrared remote sensing technology can accurately measure the thermal radiation information of targets, which means there is 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 aircraft方 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.

• YOLO-Fastest-IR: Ultra-lightweight thermal infrared face detection method for infrared thermal camera

  Xicai Li, Jiahe Zhu, Pengxiang Dong, and Yuanqing Wang

  Abstract: (4) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  This paper presents a high-speed and robust dual-band infrared thermal camera based on an ARM CPU. It is composed of a low-resolution long-wavelength infrared detector, a digital temperature and humidity sensor, and a CMOS sensor. In view of the phenomenon of large contrast between face and background in thermal infrared image, this paper we search for a suitable accuracy-latency tradeoff for thermal face detection and propose a tiny-lightweight detector named YOLO-Fastest-IR. Four different scale YOLO-Fastest-IR0 to IR3 thermal infrared face detectors based on YOLO-Fastest are designed. To train and test four tiny-lightweight models, a multi-user low-resolution thermal face database (RGBT-MLTF) is collected, and the four networks are trained. Experiments reveal that the lightweight convolutional neural network can also perform well in the thermal infrared face detection task. And the algorithm is superior to the existing face detection algorithms in positioning accuracy and speed, which is more suitable for deployment in mobile platforms or embedded devices. After obtaining the region of interest in the infrared image (IR), the RGB camera is guided by the results of thermal infrared face detection, to realize the fine positioning of RGB face. The experimental results show that YOLO-Fastest-IR has a frame rate of 92.9 FPS on a Raspberry Pi 4B and can successfully locate 97.4% of the face in the RGBT-MLTF test set. The integration of infrared temperature measurement system with low cost, strong robustness and high real-time performance was ultimately achieved, the temperature measurement accuracy can reach 0.3 degrees Celsius.

  • 1
• Precise calculation of radiation heat of cryogenic infrared detector Dewar

  zengchanghang, CHEN Jun, LI Si

  Abstract: (5) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The thermal load of the cryogenic infrared detector Dewar is a comprehensive indicator characterizing the adiabatic capacity of the Dewar. Radiative heat is a part of the thermal load. When calculating the radiative heat ,the traditional approach typically simplifies the Dewar to a coaxial cylindrical model. This simplified model differs significantly from the actual one and the traditional approach is incapable of computing the radiative heat transfer between surfaces where emissivity, transmittance, and reflectance vary with wavelength. To enhance the calculation accuracy of the Dewar's radiative heat, based on the Monte Carlo principle, a 3D Studio Max modeling was employed, model information was extracted, and a program was developed, resulting in a set of general calculation programs for the Dewar's radiative heat based on the radiation transfer factor. To preliminarily verify the accuracy of the calculation program, the cold side radiative heat of two types of experimental Dewars was calculated under the gray body assumption and the errors between the calculated and experimental values were 19 mW and 8 mW. After the initial verification of the calculation program's accuracy, considering the variations of the material surface emissivity, transmittance, and reflectance with wavelength and the influence of temperature on the radiation wavelength, the cold side radiative heat of a typical 1K×1K long-wave Dewar for engineering applications was calculated. The error between the calculated and experimental values was 17 mW. Finally, the entire radiative heat of a typical 1K×1K long-wave Dewar, a typical 1K×1K medium-wave Dewar, and a typical 640×512 medium-wave Dewar when the window surface was facing a gray body with an emissivity of 0.9 was calculated. Among them, the calculated radiative heat of the 1K×1K long-wave Dewar was 176 mW, accounting for 52% of the thermal load; the calculated radiative heat of the 1K×1K medium-wave Dewar was 166 mW, accounting for 49% of the thermal load; and the calculated radiative heat of the 640×512 medium-wave Dewar was 74 mW, accounting for 37% of the thermal load.

  • 1
• A novel photonic crystal waveguide multifunctional light-emitting beaming device

  Liu Ze-Kun, Hua Chang-Zhou

  Abstract: (4) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Based on two-dimensional triangular lattice photonic crystal, a multi-functional device of two-dimensional photonic crystal waveguide light-emitting beaming with integrated filtering function is designed, which can realize the fusion of outgoing light beaming and specific wavelength efficient filtering. The beam structure of the emitting light is similar to the grating structure, and the beam is in the state of clustering through the mutual interference principle between the multi-channel, which improves the radiation efficiency and distance of the emitting light. The finite difference time domain method can be used to obtain the effective propagation distance of 450 at the incident wavelength of 1.447. The structure design has a good beaming ability for incident light in the range of 1.435~1.465. At the same time, there are two hexagonal coupled filtering structures on either side of the waveguide, which are close to 98.4% and 97.3% transmission efficiency for incident light waves with a central wavelength of 1.490 and 1.510, respectively.The fusion structure successfully realizes the filtering and clustering functions.

  • 1
• Research on infrared imaging technology of gas plumes based on the vibe gases algorithm

  yangzhen

  Abstract: (10) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  When a gas leaks, it spreads in space by diffusion, and a dynamically stable plume of concentration usually forms near the leak source, presenting an approximate "static" region in the infrared image. This characteristic often leads to the accuracy of the commonly used moving object detection algorithm in these regions is reduced, and it is difficult to obtain the spatial concentration distribution of gas. To solve this problem, an adaptive threshold detection algorithm of Vibe Gases based on background subtraction method is proposed in this paper, and two key phases of gas plume imaging are improved. In the foreground extraction stage, the foreground difference matrix is constructed by gas detection logic and two-dimensional frequency mapping is carried out. Then the difference distribution function is fitted by least square method to calculate the optimal threshold of foreground and background separation. In the background update stage, the signal matrix of the foreground gas is constructed and two-dimensional frequency mapping is carried out. The main signal range is extracted by high-pass filtering, and the pixels located in the gas region and within the main signal range are delayed updated. The infrared detection imaging experiment shows that the detection accuracy index of ethylene at 20 meters is 91.0% and the intersection ratio index is 89.4% when the gas leakage reaches stability. The detection accuracy index of small leakage sulfur hexafluoride at 5 meters is 81.3%, and the intersection ratio index is 80.7%. The algorithm significantly improves the imaging quality of the gas plume, enhances the adaptability of detection to different gases and scenes, and effectively extracts the gas concentration distribution.

  • 1
• Multimodal Remote Sensing Image Fusion Based on Self-supervised Pre-training and Cross-scale Contrastive Learning

  LI Zhao-Wei, FENG Shi-Yang, 王斌

  Abstract: (17) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Self-supervised pre-training methods have strong capabilities in feature extraction and model transfer. However, current pre-training methods in multimodal remote sensing image (RSI) fusion only perform simple fusion operations such as concatenation on the extracted multimodal features without designing dedicated modules for the integration of multimodal information, leading to insufficient fusion of complementary information across modalities. Secondly, these methods do not consider and utilize the cross-scale consistency priors within RSIs, resulting in limited extraction and integration of multimodal remote sensing information, and thus the performance of various downstream tasks needs to be improved. In response to the above issues, a multimodal RSI fusion method based on self-supervised pre-training and cross-scale contrastive learning is proposed, which mainly includes three parts: 1) By introducing a cross-attention fusion mechanism to preliminarily integrate features extracted from different modalities, and then using encoder modules to further extract features, explicit aggregation and extraction of complementary information from each modality are achieved; 2) By introducing a cross-modality fusion mechanism, each modality can extract useful supplementary information from the features of all modalities, and reconstruct each modality’s input after separate decoding; 3) Based on the cross-scale consistency constraints of RSIs, cross-scale contrastive learning is introduced to enhance the extraction of single-modality information, achieving more robust pre-training. Experimental results on multiple public multimodal RSI fusion datasets demonstrate that, compared with existing methods, the proposed algorithm has achieved significant performance improvements in various downstream tasks. On the Globe230k dataset, our method achieves an average intersection over union (mIoU) of 79.01%, an overall accuracy (OA) of 92.56%, and an average F1 score (mF1) of 88.05%, and it has the advantages of good scalability and easy hyperparameter setting.

  • 1
• Research on key technologies of 220 GHz integrated T/R module

  YAO Chang-Fei, WENG Lv-Tao, DONG Wen-Chao, CHEN Si-Yu, WANG Hao, WANG Wen-Wei, LIU Qiang, ZHU Ming

  Abstract: (13) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  A transceiver module operating at the 220 GHz frequency band was developed, consisting of three parts: a local oscillator chain, a transmitter chain, and a receiver chain, featuring high integration. A 218~226 GHz waveguide bandpass filter was designed to suppress spurious signals in the chain. The filter adopts a dual-mode resonant cavity structure to introduce a transmission zero on the left side of the passband, which suppresses the 214 GHz spurious signal by 60 dBc. An improved E-plane magic-T structure was used to form a four-way power combining amplifier to meet the requirement of transmit power. This module achieves a power combining efficiency of 72.5% and the output power is higher than 82 mW. The measured results show that in the 219.5~221 GHz frequency range, the transmit power is 82~95 mW, the noise figure of the receiver is less than 7.1 dB, the receive gain is 5.1~6.0 dB, and the volume of module is 65×70×30 mm3.

  • 1
• Development of an active-detection mid-wave infrared search and track system based on "cat-eye effect"

  ZHOU Pan-Wei, DING Xue-Zhuan, LI Fan-Ming, YE Xi-Sheng

  Abstract: (30) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  In order to meet the urgent need of infrared search and track applications for accurate identification and positioning of infrared guidance aircraft, an active-detection mid-wave infrared search and track system (ADMWIRSTS) based on "cat-eye effect" was developed. The ADMWIRSTS mainly consists of both a light beam control subsystem and an infrared search and track subsystem. The light beam control subsystem uses an integrated opto-mechanical two-dimensional pointing mirror to realize the control function of the azimuth and pitch directions of the system, which can cover the whole airspace range of 360°×90°. The infrared search and track subsystem uses two mid-wave infrared cooled 640×512 focal plane detectors for co-aperture beam expanding, infrared and illumination laser beam combining, infrared search, and two-stage track opto-mechanical design. In this work,the system integration design and structural finite-element analysis were conducted, the search imaging and two-stage track imaging for external scenes were performed, and the active-detection technologies were experimentally verified in the laboratory. The experimental investigation results show that the system can realize the infrared search and track imaging and the accurate identification and positioning of the mid-wave infrared guidance or infrared detection system through the echo of the illumination laser. The aforementioned work has important technical significance and practical application value for the development of compactly-integrated high-precision infrared search and track and laser suppression system, and has broad application prospects in the protection of equipment, assets and infrastructures.

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• A Novel W-band Substrate Integrated Microstrip to Ultra-thin Cavity Filter Transition

  CAO Yi, TANG Xiao-Hong, LIU Yong, CAI Zong-Qi

  Abstract: (14) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Abstract—A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter. The structure is a new method of connecting microstrip circuits and waveguide filters, and this new structure enables a planar integrated transition from microstrip lines to ultra-thin cavity filters, thereby reducing the size of the transition structure and achieving miniaturization. The structure includes a conventional tapered microstrip transition structure, which guides the electromagnetic field from the microstrip line to the reduced-height dielectric-filled waveguide, and an air-filled matching cavity which is placed between the dielectric-filled waveguide and the ultra-thin cavity filter. The height of the microstrip line, dielectric-filled waveguide and the ultra-thin cavity filter are the same, enabling seamless integration within a planar radio-frequency (RF) circuit. To facilitate testing, mature finline transition structures are integrated at both ends of the microstrip line during fabrication. The simulation results of the fabricated microstrip to ultra-thin cavity filter transition with the finline transition structure, with a passband of 91.5-96.5 GHz, has an insertion loss of less than 1.9 dB and a return loss lower than -20 dB. And the whole structure has also been measured which achieves an insertion loss less than 2.6 dB and a return loss lower than -15dB within the filter's passband, including the additional insertion loss introduced by the finline transitions. Finally, a W-band compact up-conversion module is designed, and the test results show that after using the proposed structure, the module achieves 95 dBc suppression of the 84 GHz local oscillator. It is also demonstrated that the structure proposed in this letter achieves miniaturization of the system integration without compromising the filter performance.

  • 1
• Design of a wideband non-uniform microstrip line for complex impedance matching at automotive radar frequency

  ZHANG Shuang-Gen, YU Tao, WANG Yu-Lan, CHENG Zhi-Hua, YAO Jian-Quan

  Abstract: (18) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly impacts on the radiation efficiency and bandwidth of the antenna. Here, a wideband non-uniform wavy microstrip line for complex impedance at automotive radar frequency range is proposed. Different to the gradient transmission line, the wavy structure is composed of periodically semi-circular segments. By adjusting the radius of the semi-circular, the surface current varied and concentrated on the semi-circular segments, allowing a wider tunability range of the resonant frequency. The results reveal that the bandwidth of the loaded wavy transmission line antenna improves up to 9.37 GHz, which is 5.81 GHz wider than that of the loaded gradient line. The gain and the half power beam width of the loaded antenna are about 14.69 dB and 9.58°, respectively. The proposed non-uniform microstrip line scheme may open up a route for realizing wideband millimeter wave automotive radar applications.

  • 1
• Fabrication and characterization of InGaAs/InAlAs photoconductive terahertz detection antenna with dynamic range exceeding 75 dB

  JIANG Qing-Nan, TAN Zhi-Yong, WAN Wen-Jian, FU Zhang-Long, XIA Yu, LI Min, CAO Jun-Cheng

  Abstract: (26) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The photoconductive antenna is a very important device in the terahertz region and is widely used in terahertz time-domain spectroscopy technology. This article uses the molecular beam epitaxy method to grow Be-doped InGaAs/InAlAs superlattice as light absorbing materials for 1550 nm laser pumped photoconductive antenna for terahertz detection. The prepared materials have a sheet resistance greater than 106 ^{Ω/sq and an electron mobility of 216 cm}2^{/(Vs); The active} mesa and electrode structure of the detection antenna are prepared using wet etching and magnetron sputtering processes, and the antenna chip is packaged on a PCB board. A detection antenna measurement system is built by employing a domestically produced 1550 nm femtosecond pump laser, and the detection antennas with electrode gaps of 40 μm and 60 μm were characterized; The measurement results indicate that the 60 μm antenna has a wider spectral width and power dynamic range, reaching 4.0 THz and 77.0 dB, respectively.

  • 1

Volume 43,2024 Issue 6

• SEGMENTATION BASED ON MUMFORD-SHAH MODEL COMBINED WITH NARROW BAND

  Abstract

  2002,21(3):161-166, DOI:

  Abstract: (2442) HTML (123) PDF (392.26 KKB)(87673)

  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.

• TWO-FREQUENCY SCATTERING CROSS SECTION AND PULSE BROADINGENING FOR THE FRACTAL SEA SURFACE WITH PULSE BEAM INCIDENCE

  GUO Li Xin 1) KIM Che Young 2)

  2003,22(2):132-136, DOI:

  Abstract: (998) HTML (132) PDF (396.69 KKB)(54818)

  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。

• LOW-TEMPERATURE RAMAN SCATTERING SPECTRA AND ELECTRICAL PROPERTIES OF Cd_1-xZn_xTe(x=0.04) OF DIFFERENT SURFACE TREATMENTS

  PEI Hui-Yuan

  2001,20(3):184-188, DOI:

  Abstract: (1688) HTML (139) PDF (262.82 KKB)(53069)

  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。

• OPTICAL SPECTRA OF LOW-DIMENSIONAL SEMICONDUCTORS

  FuY ChiragwandiZ GoethbergP WillanderM

  2003,22(6):401-405, DOI:

  Abstract: (1018) HTML (128) PDF (483.11 KKB)(22941)

  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.

• OPTICAL PROPERTIES OF PbTiO3 THIN FILMS PREPARED BY A MODIFIED SOL-GEL PROCESSING

  HU Zhi Gao WANG Gen Shui HUANG Zhi Ming CHU Jun Hao

  2002,21(3):175-179, DOI:

  Abstract: (7745) HTML (465) PDF (411.06 KKB)(22006)

  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。

Infrared Spectroscopy and Remote Sensing Technology

• DETECTING THE MELAMINE OF PURE MILK BY NEAR INFRARED SPECTRA

  XU Yun, WANG Yi-Ming, WU Jing-Zhu, ZHANG Xiao-Chao

  2010,29(1):53-56, DOI:

  Abstract: (10577) HTML (415) PDF (221.64 KKB)(15884)

  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.

• INFRARED OBJECT TRACKING BASED ON PARTICLE FILTERS

  CHENG Jian, ZHOU Yue, CAI Nian, YANG Jie

  2006,25(2):113-117, DOI:

  Abstract: (7359) HTML (402) PDF (271.63 KKB)(15225)

  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.

• A NOVEL NEURAL NETWORK LEARNING METHOD OF DYNAMICALLY TUNING REGULARIZATION COEFFICIENT ACCORDINT TO FUZZY RULES

  WU Yan 1), 2) ZHANG Li Ming 2)

  2002,21(3):189-194, DOI:

  Abstract: (1422) HTML (94) PDF (450.58 KKB)(14886)

  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.

• HYPERSPECTRAL REMOTE SENSING IMAGE CLASSIFICATION BASED ON SUPPORT VECTOR MACHINE

  TAN Kun, DU Pei-Jun

  2008,27(2):123-128, DOI:

  Abstract: (2979) HTML (936) PDF (735.00 KKB)(13030)

  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.

Interdisciplinary Research on Infrared Science

• INFRARED TARGET EXTRACTION ALGORITHM BY USING PARTICLE SWARM OPTIMIZATION PARTICLE FILTER

  ZHOU Yue, MAO Xiao-Nan

  2010,29(1):63-68, DOI:

  Abstract: (11398) HTML (439) PDF (750.21 KKB)(12746)

  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.

Remote Sensing Technology and Application

• A method for fire detection using Landsat 8 data

  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: (3775) HTML (239) PDF (5.05 MKB)(12731)

  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%.

Interdisciplinary Research on Infrared Science

• IMAGE SEGMENTATION BY SPECTRAL CLUSTERING ALGORITHM WITH SPATIAL COHERENCE CONSTRAINTS

  JIA Jian-Hua, JIAO Li-Cheng

  2010,29(1):69-74, DOI:

  Abstract: (11442) HTML (387) PDF (808.83 KKB)(12708)

  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.

• IMAGE FUSION SCHEME OF PIXEL-LEVEL AND MULTI-OPERATOR FOR INFRARED AND VISIBLE LIGHT IMAGES

  LIU Gui Xi YANG Wan Hai

  2001,20(3):207-210, DOI:

  Abstract: (1273) HTML (111) PDF (196.71 KKB)(12677)

  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.

Infrared Physics, Materials and Devices

• Graphene oxide: progress in preparation, reduction and application

  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: (3305) HTML (215) PDF (4.42 MKB)(12578)

  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.

• IMAGE RETRIEVAL BASED ON IMAGE ENTROPY AND SPATIAL DISTRIBUTION ENTROPY

  SUN Jun-Ding, DING Zhen-Guo, ZHOU Li-Hua

  2005,24(2):135-139, DOI:

  Abstract: (1442) HTML (99) PDF (380.01 KKB)(11775)

  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.

• 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: (11800) HTML (435) PDF (1.12 MKB)(11773)

  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.

• METHOD OF SCATTERING CENTER ESTIMATION BY RADAR TARGET FREQUENCY RESPONSE DATA IN CLUTTER ENVIRONMENT

  JIANG Wei Dong CHEN Zen Ping ZHUANG Zhao Wen GUO Gui Rong

  2001,20(2):111-116, DOI:

  Abstract: (922) HTML (103) PDF (331.55 KKB)(11648)

  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.

Millimeter Waves and Terahertz Technology

• Design and experimental verification of band-pass frequency selective surface based on metamaterial effective medium theory

  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: (2757) HTML (131) PDF (1.09 MKB)(10439)

  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.

• RESEARCH ON ELECTRO-INDUCED BIREFRINGENCE IN CRYSTAL SILICON

  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: (7901) HTML (181) PDF (466.11 KKB)(10341)

  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.

• SURFACE COMPONENT CHANGE OF Hg0.8Cd0.2Te INDUCED BY HIGH POWER PULSED TEA-CO2 LASER

  CAI Hu, CHENG Zu-Hai, ZHU Hai-Hong, ZUO Du-Luo

  2006,25(3):165-169, DOI:

  Abstract: (978) HTML (109) PDF (434.30 KKB)(10125)

  Abstract:

  利用场发射扫描电子显微镜对TEA-CO2强激光脉冲辐照的Hg0.8Cd0.2Te晶片表面进行了观察,并利用电镜自带的能谱分析仪对其表面进行了成分分析.在单脉冲能量为1.91J,峰值功率密度为2.63×107W/cm2的脉冲CO2激光辐照下,晶片表面呈现出熔融迹象,且晶片表面的化学组分比发生明显的变化.理论与实验研究结果表明激光急速加热使晶体表面的Hg-Te键破坏,从而导致Hg损失,而Hg损失程度与热作用过程的时间有关.随着脉冲作用次数的增加,多脉冲的连续作用使Hg损失加剧,晶片表面成分变化更加突出.