Volume 42,2023 Issue 2

Infrared Materials and Devices

• Simulation on the saturation properties of room-temperature mid-wave infrared HgCdTe detectors

  LI Xiang-Yang, SANG Mao-Sheng, XU Guo-Qing, QIAO Hui, CHU Kai-Hui, YANG Xiao-yang, YANG Peng-Ling, WANG Da-Hui

  2023,42(2):143-148, DOI: 10.11972/j.issn.1001-9014.2023.02.001

  Abstract: (105) HTML (41) PDF (962.67 KKB)(213)

  Abstract:

  The photovoltaic mid-wave infrared HgCdTe detector， which is operated at room temperature， is simulated to explore laser irradiation saturation characteristics. The results reveal that the heating effect on the HgCdTe material and the lowering of the zero-bias impedance due to irradiation， are significant factors affecting the quantum efficiency of the detector. The model of HgCdTe pn junction is established， and a one-dimensional numerical simulation method is adopted to compute the quantum efficiency and zero-bias impedance of device. The device is irradiated under steady-state. Moreover， the temperature field distribution is coupled in the simulation， the thickness of substrate affects the temperature of the detector， which significantly affects the saturation threshold of the device. Furthermore， the calculations show that the zero-bias impedance of device decreases when the light intensity is raised. The result is compared to the measured performance of device. Finally， the computational analysis serves as a foundation for the development of mid-wave IR HgCdTe detectors with high saturation irradiance threshold.

• Analysis and control of abnormal phenomena in HgCdTe surface treatment

  LIU Yan-Zhen, LI Shu-Jie, ZHANG Ying-Xu, XIN Yong-Gang, LI Zhi-Hua, LIN Yang, LI Xiong-Jun, QIN Qiang, JIANG Jun, GUO Jian-Hua

  2023,42(2):149-155, DOI: 10.11972/j.issn.1001-9014.2023.02.002

  Abstract: (100) HTML (19) PDF (2.57 MKB)(167)

  Abstract:

  The surface treatment is the beginning of the manufacturing process of HgCdTe infrared detector chip， and its quality will directly affect the yield of the chip. The mechanisms of four typical surface anomalies in the HgCdTe surface treatment process were explored using metallographic microscope， scanning electron microscope （SEM） and X-ray photoelectron spectroscopy （XPS） analysis methods， and the corresponding control measures are proposed. The water mark defect is triggered by oxygen absorption corrosion， and this defect can be controlled by rapidly drying the HgCdTe surface with a stable nitrogen gas flow. The staining is induced by the corrosive liquid unevenly diluted or contaminated by impurities such as water. To reduce the probability of staining， the contamination should be strictly avoided in the process， and the surface should be quickly rinsed after corrosion finish. The round spot originates from the adsorption of the cleaning solution at the material defect， which can be controlled via using isopropanol to soak the HgCdTe before drying. When toluene is in direct contact with HgCdTe， the surface roughness of HgCdTe will increase， thus this direct contact should be restricted.

• The study of magneto-optical conductivity of monolayer MoS₂

  LI Yue, XIAO Yi-Ming, XU Wen

  2023,42(2):156-161, DOI: 10.11972/j.issn.1001-9014.2023.02.003

  Abstract: (75) HTML (20) PDF (1.19 MKB)(136)

  Abstract:

  The longitudinal magneto-optical conductivity of monolayer molybdenum disulfide （ML-MoS₂） has been theoretically investigated under the quantizing Landau levels induced by applied magnetic field and proximity-induced exchange interaction via using the random-phase approximation （RPA） dielectric function approach. The effects of the proximity-induced exchange interaction and magnetic field on the longitudinal magneto-optical conductivity are examined. There are two magneto-optical absorption peaks induced by the transitions processes within the conduction band in Terahertz （THz） frequency range. The inter-band transitions between conduction and valence bands result in a series of magneto-optical absorption peaks in the visible frequency range. The results indicate that the magnetic field and proximity-induced exchange interaction could have important influence on the longitudinal magneto-optical conductivity of ML-MoS₂ and it could be applied in promising magneto-optics devices for spintronics and valleytronics working from visible to THz frequency range.

• Band alignment engineering of bilayer WS₂/Ga₂O₃ heterostructures with interface-dependent photoluminescence

  YANG Wan-Li, HUANG Tian-Tian, ZHANG Le-Peng, XU Pei-Ran, JIANG Cong, LI Tian-Xin, CHEN Zhi-Min, CHEN Xin, DAI Ning

  2023,42(2):162-168, DOI: 10.11972/j.issn.1001-9014.2023.02.004

  Abstract: (53) HTML (15) PDF (1.84 MKB)(118)

  Abstract:

  The hetero-interface induced anomalous photoluminescence （PL） emissions in the vertical WS₂/Ga₂O₃ heterostructures was demonstrated. The WS₂/Ga₂O₃ hetero-interface varies type-II band structure and brings subsequent PL decline in the bottom WS₂ monolayer contacted with Ga₂O₃ layer. Such hetero-interlayer coupling interaction between oxides and 2D layered transition metal dichalcogenides （TMDs） in the stacked heterostructures impacts interlayer interaction between the bottom WS₂ monolayer and the upper WS₂ monolayer in a WS₂ bilayer， which leads to an anomalous PL enhancement in the bilayer WS₂. Stacked hetero-interface will benefit for controlling the optical or electronic behavior and modulating energy band structures by customizing transformative 2D heterostructures used in next-generation nanoscale optoelectronic detectors and photodetectors.

• Research progress of ultra-broadband photodetectors

  LIU Yu, LIN Zhi-Cheng, WANG Peng-Fei, HUANG Feng, SUN Jia-Lin

  2023,42(2):169-187, DOI: 10.11972/j.issn.1001-9014.2023.02.005

  Abstract: (101) HTML (29) PDF (2.06 MKB)(318)

  Abstract:

  Photodetectors play a key role in many applications， such as remote sensing， night vision， reconnaissance， medical imaging， thermal imaging， and chemical detection. With the increasing complexity of photoelectric detection tasks， photodetectors working in different bands are gradually integrated into broad spectral detection for the same scene. Limited by the volume and task module of the integrated system， conventional broad spectral detection tasks often require multiple detectors working in different bands to perform together， which greatly increases the complexity of detection system. Therefore， photodetector enabling to response ultra-broadband radiation （UV-vis-IR-THz） has gradually become a subject of great interest in recent years. However， there have been no reports on the review of ultra-broadband photodetectors so far. Hence， this review systematically summarizes the research progresses of ultra-broadband photodetectors in the past ten years. The factors affecting the response performance of photodetectors and the main types of common photodetectors are described first， and then the research progress， development status and challenges are reviewed and suggestions about the future research directions of ultra-broadband photodetectors are also provided.

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Terahertz and Millimeter Wave Technology

• Research on the adaptability of space environment about NbN superconducting SIS mixer for high sensitivity terahertz detection module

  ZHANG Kun, YAO Ming, LIU Dong, LIU Bo-Liang, LI Jing, YAO Qi-Jun, SHI Sheng-Cai

  2023,42(2):188-192, DOI: 10.11972/j.issn.1001-9014.2023.02.006

  Abstract: (38) HTML (8) PDF (1.14 MKB)(141)

  Abstract:

  The high sensitivity terahertz detection module （HSTDM） is one of the scientific instruments of the China Sky Survey Telescope. HSTDM is a high-resolution spectrometer and the first space heterodyne receiver using niobium nitride （NbN）-based superconducting tunnel junction （Superconductor - Insulator - Superconductor （SIS）） mixer （the NbN SIS mixer）. The NbN SIS mixer must meet the specification requested for a space environment， such as high operation reliability， robustness to vibration， cosmic irradiation， and thermal variation. This paper presents the space qualification tests performed on the NbN SIS mixer， including sine and random vibration tests， single-particle irradiation test， total dose radiation test， and thermal cycling test. The mixer’s performance analysis confirms that it can meet the space application requirements of HSTDM.

• The THz image resolution enhancement algorithm based on PSF

  XIE Bin

  2023,42(2):193-196, DOI: 10.11972/j.issn.1001-9014.2023.02.007

  Abstract: (60) HTML (11) PDF (1.00 MKB)(112)

  Abstract:

  In recent years， terahertz （THz） imaging technology has received increased attention owing to the promising imaging tools now available for nondestructive testing. However， theoretical models of THz imaging systems are yet to be developed. In this study， we proposed a comprehensive mathematical modeling and simulation theory for the THz imaging system. Gaussian beam distribution was used in the mathematical modeling of the point spread function （PSF）. The target function was convolved using the PSF， and the analog transmission of THz images was realized. The PSF of the imaging system was calculated using the optical imaging method. Next， the image was deconvolution-enhanced using the PSF. The image restoration results revealed that the image resolution improved. The restored image contains more details.

• A 33~170 GHz cascode amplifier based on InP DHBT technology

  WANG Bo-Wu, YU Wei-Hua, HOU Yan-Fei, YU Qin, SUN Yan, CHENG Wei, ZHOU Ming

  2023,42(2):197-200, DOI: 10.11972/j.issn.1001-9014.2023.02.008

  Abstract: (29) HTML (12) PDF (1.56 MKB)(142)

  Abstract:

  In this paper， a wide band cascode power amplifier working at 33~170 GHz is designed， based on the 500 nm InP dual-heterojunction bipolar transistor （DHBT） process. Two pairs of parallel input and output stub lines can effectively expand the working bandwidth. The output coupling line compensates the high frequency transmission. The measured results show that the maximum gain of the amplifier is 11.98 dB at 115 GHz， the relative bandwidth is 134.98 %， the gain flatness is ±2 dB， the gain is better than 10 dB and the output power is better than 1 dBm in the operating bandwidth.

• Study on terahertz spectral properties of pores in glass fiber composites

  XU Tuo, LU Xing-Xing, SHEN Yan, ZHANG Jin-Bo, CHANG Tian-Ying, CUI Hong-Liang, ZHANG Jin

  2023,42(2):201-207, DOI: 10.11972/j.issn.1001-9014.2023.02.009

  Abstract: (38) HTML (7) PDF (2.03 MKB)(105)

  Abstract:

  The interaction mechanism between terahertz waves and pore defect in glass fiber composites is explored， and the interaction relationship between porosity and terahertz characteristic parameters （refractive index， extinction coefficient and transmission coefficient） is analyzed at 0.075 and 0.713 THz frequency points. The experimental results show that the density and refractive index of glass fiber composites decrease with the increase in porosity. When the frequency is 0.075 THz， the extinction coefficient decreases and the transmission coefficient increases with the increase in porosity based on Rayleigh scattering theory. At 0.713 THz， based on Mie scattering theory， the extinction coefficient increases and the transmission coefficient decreases with the increase in porosity. In addition， the complex and changeable pore morphology results in a non-unique correspondence between porosity and terahertz characteristic parameters. When the different samples have the same porosity， the terahertz characteristic parameters are not the same.

• Temperature uniformity and thermal deformation analysis of the cathode with radiation heating in the magnetron injection electron gun

  YANG Ming-Zhe, WANG Xiao-Xia, FAN Yu, MENG Ming-Feng, YANG Chen, GAO Cha, LUO Ji-Run

  2023,42(2):208-214, DOI: 10.11972/j.issn.1001-9014.2023.02.010

  Abstract: (37) HTML (14) PDF (1.72 MKB)(88)

  Abstract:

  Based on the development of a magnetron injection electron gun（MIG） for gyrotron oscillator operating at 140 GHz and with about a megawatt output power， the temperature homogeneity of the cathode and thermal deformation of the MIG were analyzed with ANSYS code. Under an improved temperature homogeneity of the cathode， the geometrical and electrical parameters have been adjusted and optimized to eliminate the effect of thermal deformation on beam trajectory. The simulated temperature of the cathode will be compared with the tested one for evaluating the rationality of the simulation model， which may be helpful for the actual design.

• Dual-tunable triple-band absorber based on bulk Dirac semimetal and vanadium dioxide

  HU Bao-Jing, HUANG Ming, DING Hong-Wei, HONG Su-Mei

  2023,42(2):215-222, DOI: 10.11972/j.issn.1001-9014.2023.02.011

  Abstract: (40) HTML (8) PDF (2.76 MKB)(97)

  Abstract:

  In this paper， a dual-tunable triple-band absorber based on bulk Dirac semimetal （BDS） and vanadium dioxide （VO₂） is proposed. The electromagnetic properties of the absorber are analyzed by the finite difference time domain method and equivalent circuit model （ECM）. When the VO₂ is in fully metallic state， the absorption spectrum of the dual-tunable absorber exhibits three obvious absorption peaks with the average absorptance being 98.64%. The resonant frequencies and absorptivity of the absorber can be dynamically controlled by adjusting the Fermi energies of BDS and the conductivities of VO₂. Finally， the relationships between the absorptivity of the dual-tunable absorber and the different thicknesses of the BDS， VO₂ and immediate dielectric layers are further discussed. This work provides potential applications in the designs of multi-banddual-tunable filters and absorbers.

• Millimeter wave high scanning rate quad-beam leaky wave antenna based on spoof surface plasmon polaritons （SSPP）

  PENG Zhen, ZHAI Guo-Hua, HUANG Dai-Xin, REN Ji-Shan, GAO Jian-Jun

  2023,42(2):223-228, DOI: 10.11972/j.issn.1001-9014.2023.02.012

  Abstract: (44) HTML (11) PDF (1.50 MKB)(158)

  Abstract:

  In order to enhance the multi-object detecting and tracking capability， a four-beam millimeter wave frequency scanning leaky wave antenna （LWA） based on spoof surface plasmon polaritons （SSPP） has been proposed. According to the theory of sinusoidally modulated reactance superposing surface （SMRSS）， Quad-beam LWA is realized by etching periodical slots on the top surface of substrate integrated waveguide （SIW）， and uniform slots etched on the bottom layer is used to eliminate the open-stopband effect. The measurement shows that the four beams can scan from -52° to 22° within the frequency band from 29 GHz to 30.2 GHz， achieving a total of 74° scanning range， and the beam scanning is up to 18°/%BW， which not only saves the spectrum source but improvs the multi-target detection efficiency.

• 335 GHz unbalanced Schottky diode frequency tripler

  LI Yu-Hang, ZHANG De-Hai, MENG Jin, QI Lu-Wei

  2023,42(2):229-233, DOI: 10.11972/j.issn.1001-9014.2023.02.013

  Abstract: (40) HTML (7) PDF (1.76 MKB)(123)

  Abstract:

  Based on the hybrid integration method， a 335 GHz unbalanced frequency tripler is designed with a symmetrical tapered gradient line matching structure. Under the condition of ensuring single-mode transmission， the matching structure can not only fix the diode position， but also increase the matching effect， and thus solve the problem of narrow 3dB bandwidth for high-frequency band multiplier. The measured results show that the output power of the frequency tripler is all greater than 5 mW in the frequency range of 330-356 GHz. The maximum output power even reaches 11.2 mW at a driving power of 220 mW. The solid-state terahertz local oscillator， as the core device， can drive the 670 GHz sub-harmonic mixer in the superheterodyne receiver.

• On the design of high conversion efficiency quasi-optical mode converter for 140 GHz high-power gyrotron applications

  JIN Ming, WANG Dan-Yang, ZHANG Yi-Chi, HAN Yu-Nan, BAI Ming

  2023,42(2):234-240, DOI: 10.11972/j.issn.1001-9014.2023.02.014

  Abstract: (34) HTML (11) PDF (3.17 MKB)(87)

  Abstract:

  A high conversion efficiency quasi-optical mode converter prototype is designed for 140 GHz TE_22，6 applications. The Denisov launcher is designed based on the periodic perturbation concept， leading to primary radiation field with low edge diffraction. Full-vector physical optics integration solver is used to model and analyze the 3-mirror system. And the 3-mirror iterative phase correction is applied based on the co-polarization field component， so as to achieve high-quality mode conversion. Specifically， the correction of the 1^st mirror sufficiently refines the non-ideal radiated fields from the launcher. It is then validated by numerical investigations that， comparing to the original quaritic mirrors， the phase-shaped mirror system leads to excellent conversion performance. The Gaussian content （η_v） of the output fields rises from 92.7% to 99.6%， while the power transmission efficiency （η_p） reaches 98.8%.

Remote Sensing Technology and Application

• A new index for low-light-level remote sensing identification of forest fires： the enhanced noctilucent fire disturbance index

  WU Jin-Wen, JI Rui-Peng, ZHANG Yu-Shu, SUN Long-Yu, YU Wen-Ying, FENG Rui, XING Fang

  2023,42(2):241-249, DOI: 10.11972/j.issn.1001-9014.2023.02.015

  Abstract: (42) HTML (12) PDF (3.49 MKB)(113)

  Abstract:

  With the development of optoelectronic technology， low-light-level （LLL） imaging technology and its application have recently become a research focus. In LLL remote sensing images， it is difficult to completely separate forest fires from industrial combustion and urban heat sources based on radiance or temperature alone. Meanwhile， because of frequent data saturation in the low-light band， the existing fire detection products only provide detection information. To identify forest fires among various heterogeneous heat sources with high brightness and further improve the pixel-level characterization of fire detection products， a new spectral index， the enhanced noctilucent fire disturbance index （ENFDI），is proposed based on the principle that surface temperature decreases with the increasing vegetation density by Latent heat transfer. According to the results， ENFDI enhances the differences in spectral characteristics between forest fires and city lights and improves the ability of forest fire identification under low-light conditions. The forest fires’ ENFDI are significantly higher than those of urban heat sources.Moreover， ENFDI can also effectively relieve the impact caused by LLL band’s proneness to saturation. Not only can ENFDI clearly distinguish flame glow differences within potential saturation zones and enhance the distinguishability of forest fire’s pixels， but the correlation （R） between ENFDI and the mid-and far-infrared brightness temperature difference is as high as 0.94–0.97， which is considerably higher than that of NTL （0.82-0.83）.Furthermore， ENFDI is relatively stable —it is not affected by lunar phases in that forest fires at night are identified with or without moonlight. ENFDI recorded an 87.66% forest fire identification accuracy in this study， which is higher than the 83.91% accuracy of the conventional TMIR method. The forest fires identified using the ENFDI show a good overall correspondence with the NPP/VIIRS active fire product （VNP14IMG）， with a positional tolerance within 628 m. Therefore， ENFDI is sensitive， stable and accurate for identifying forest fires. Further， it may serve as a feasible reference for achieving further pixel-level characterization of fires.

• Spaceborne photon counting lidar point cloud denoising method with the adaptive mountain slope

  HE Guang-Hui, WANG Hong, FANG Qiang, ZHANG Yong-An, ZHAO Dan-Lu, ZHANG Ya-Ping

  2023,42(2):250-259, DOI: 10.11972/j.issn.1001-9014.2023.02.016

  Abstract: (51) HTML (16) PDF (4.78 MKB)(119)

  Abstract:

  A large amount of noise will be generated while spaceborne photon counting LIDAR receive signals， and the signal-to-noise ratio is lower in complex mountainous land， which greatly affects the accurate extraction of vegetation point cloud signals. This paper proposes a density clustering algorithm based on the mountain slope to solve this problem. By analyzing the density of point cloud data and the terrain characteristics of forest targets， coarse noise removal is performed by using the maximum density center search method， and then the slope angle is calculated based on the point cloud data to optimize density clustering and complete the data fine noise removal. By classifying the extracted forest region signal， fitting the vegetation canopy profile and the surface profile， the results show that the proposed algorithm has high accuracy in the extraction of vegetation photon signal， and the RMSE of the ground and canopy profiles are 0.3588 m and 3.7449 m， respectively， which is more suitable for vegetation remote sensing point cloud data processing.

Infrared Photoelectric Technology and Application

• Modeling and analysis for imaging characteristics of infrared array-aperture diffractive optical system

  NIU Rui-Ze, QIAO Kai, ZHI Xi-Yang, GONG Jin-Nan, JIANG Shi-Kai, TIAN Chao

  2023,42(2):260-266, DOI: 10.11972/j.issn.1001-9014.2023.02.017

  Abstract: (47) HTML (6) PDF (2.05 MKB)(100)

  Abstract:

  This paper establishes the modulation transfer function （MTF） and signal-to-noise ratio （SNR） characterization models of the infrared array-aperture diffractive optical system based on the diffraction imaging mechanism. Subsequently， the imaging system diffraction efficiency is calculated based on the three-dimensional Finite Difference Time Domain （FDTD） method and the imaging characteristics are represented by combining the MTF and SNR. Finally， the effects of different working wavelengths， field of views and filling factors of the primary lens imaging characteristics are analyzed. The analysis results show that the diffraction efficiency， the MTF and SNR of infrared array-aperture diffractive optical system all have spectral and spatial variation characteristics， which reduce with the decrease of the primary lens filling factor. When the filling factor is 0.6， the integral area of MTF decreases by 45.42% and the SNR decreases by 4.92 dB compared with the ideal full aperture system. The established model can be used to characterize the imaging quality of infrared array-aperture diffractive optical system and provide reference to the imaging system design.

• Optimization of structural parameters of a 1.06 µm non-polarization mode-locked fiber laser

  ZHANG Jia-Rui, WANG Ji, HE Xing-Kai, SHEN Qi-Hao, FAN Qi, ZHOU Ding-Fu, WANG You

  2023,42(2):267-275, DOI: 10.11972/j.issn.1001-9014.2023.02.018

  Abstract: (33) HTML (15) PDF (1.99 MKB)(113)

  Abstract:

  A mode-locked fiber laser using Semiconductor Saturable Absorber Mirrors （SESAMs） is one of the popular candidate seed light sources for the construction of picosecond pulse fiber amplifier. In this paper， the influence of the fiber length of a gain fiber， the reflectance of the Fiber Bragg Grating （FBG）， the modulation depth， the unsaturated loss， and the saturation flux of SESAMs， the mode field radii of single-mode transmission fibers and a single-mode gain fiber， on the output pulse characteristics， have been theoretically analyzed using the nonlinear Schrodinger equations. The characteristics of the pulse and the spectrum of an outputted laser have also been investigated theoretically. According to the simulation results， we built an ytterbium-doped mode-locking fiber laser system based on the non-polarization-maintaining linear cavity and a SESAM. Without any compensation for intra-cavity dispersion and external polarization control， a stable mode-locked pulse laser output has been achieved with the center wavelength of 1.06 μm， the pulse width of less than 12.51 ps， the spectral width of 0.32 nm， the repetition rate of 37 MHz， and the output power of 2 mW， respectively. The spectral edges of laser pulses appear smooth in our experiment， and the spectral distribution is close to the Gaussian shape. Finally， the overall structure of the near-infrared mode-locked fiber laser has been optimized by the systematic simulation. The mode-locked fiber laser introduced in this paper has a compact non-polarization-maintaining fiber structure， simple intra-cavity configuration with fewer components， high-quality output pulse correlation characteristics， which might provide a practical seed light source with the excellent performance for the next-generation picosecond pulse fiber lasers.

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Image Processing and Software Simulation

• Head motion detection based on low resolution infrared array sensor

  CHEN Liang-Qin, ZENG Ming-Xuan, XU Zhi-Meng, CHEN Zhi-Zhang

  2023,42(2):276-284, DOI: 10.11972/j.issn.1001-9014.2023.02.019

  Abstract: (44) HTML (15) PDF (3.20 MKB)(129)

  Abstract:

  People easily get distracted or tired after long-duration actions such as driving and online classes， which can lead to accidents or poor efficiency. To detect such human behaviors， a head motion detection method based on low-resolution infrared array sensors is proposed with the protection of personal privacy. First， prominent areas of the human body are extracted based on image processing techniques. Then a 3D image fusion algorithm is developed to extract the change information in the spatiotemporal domain. Finally， an improved residual network is developed to achieve head motion classification. Ten head movements are designed for driving and online classroom scenarios. Experimental results show that in the detection range of 50 cm to 100 cm， our average recognition rate is 96.76%， and the processing speed is 9 frames per second， which is better than the existing state-of-the-art algorithms. The accuracy of the system is 93.7% when it is applied to the vehicle experiment.

Volume 42,2023 Issue 2

太赫兹与毫米波技术

• Numerical simulation of scanning nearfield optical microscopy based on the source dipole model

  WU Chang-Lin, WANG Chang, CAO Jun-Cheng

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

  Abstract: (40) HTML (0) PDF (1.66 MKB)(36)

  Abstract:

  Scanning near-field optical microscopy in the infrared and terahertz ranges has attracted much interest in studying objects far below the diffraction limit. Particularly in the detection of optical properties of structures on the nanoscale. To further understand the tip-sample interaction， analytical and numerical description of the near fields from the probe is essential. Here， we established and analytically solved a more realistic analytical model based on the real probe shape. Based on the combination of the analytical model and numerical simulation to develop the source dipole model （SDM）. A comparison with the new method to full-wave simulation （FWS） results was performed. In simulations combined with the theoretical model， the detection information is obtained directly， and the computational efficiency is improved. Based on simulation results， the antenna effect， tip apex radius influence， and the influence of charge amount are explained. And providing a new perspective to further understand the tip-sample junction in optical nanoscopy.

红外及光电技术与应用

• Infrared small target detection based on clustering idea

  Rao Jun-Min, Mu Jing, Liu Shi-Jian, Gong Jin-Fu, Li Fan-Ming

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

  Abstract: (29) HTML (0) PDF (1.50 MKB)(72)

  Abstract:

  In order to solve the problem of detecting infrared small targets of unknown size in complex background， an infrared small target detection algorithm based on clustering idea is proposed. First， original infrared image is preprocessed by using small target morphological features to generate a new density feature map. Secondly， the potential candidate targets are coarsely localized with an improved density-peak clustering algorithm. Then， the local candidate sets of potential targets are constructed. A weighted fuzzy set clustering algorithm is used to finely segment the target and background regions of the image block， and then the difference between the target and background is adopted to suppress false alarms while enhancing the target. Finally， an adaptive threshold is applied to the processed local candidate set to extract the real target. Experimental results show that the proposed algorithm has good robustness and detection performance for small targets of unknown size in comparison with other seven methods.

太赫兹与毫米波技术

• Research on watt-level power combining technology at terahertz band based on bonding wire compensation

  ZHU Xiang, ZHANG Jun-Jie, CHENG Hai-Feng, GUO Jian, SHI Yong-Rong, WANG Wei-Bo

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

  Abstract: (45) HTML (0) PDF (1.85 MKB)(87)

  Abstract:

  With the application demand of solid-state high power at the terahertz （THz） band， a THz-band watt-level power output is achieved by adopting GaN power amplifier （PA） MMIC and power combining technology. Microstrip-waveguide transition， and the low-loss interconnection based on the gold wire compensation are used to package a PA module composed of two PA MMICs and an E-plane T-junction two-way power splitter/combiner. Maximum output power of 160mW is achieved. Based on the module and an eight-way E-plane combiner， a sixteen-way power combining amplifier is designed across the frequency range of 180 to 238GHz. Output power of more than 300mW is achieved with +10V drain voltage， and the maximum power is 1.03W at 189GHz.

图像处理及软件仿真

• The Infrared Point Target Detection Algorithm based on Modified Random Walker and Non-convex Rank Approximation Minimization Under the Complex Background

  WANG Kun, JIANG De-fu, YUN Li-Jun, Wu ling-fan

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

  Abstract: (52) HTML (0) PDF (1.71 MKB)(42)

  Abstract:

  Infrared point target detection is one of the key technologies of infrared guidance system. On the one hand, due to long observation distance, the point target is often submerged in the background clutter and large noise in the process of atmospheric transmission and scattering, and the signal-to-noise ratio is low. On the other hand, the target in the image appears in the form of fuzzy points, so that the target has no obvious features and texture information. Therefore, due to these two factors, infrared point target detection becomes intensely difficult. In order to address the issue, the relevant algorithms of point infrared target detection are studied, and a combination algorithms of non-convex rank approximation minimization algorithm and the modified random walker algorithm (NRAM-MRW) is proposed, which has a better detection effect of point infrared target detection under complex background.

太赫兹与毫米波技术

• Investigation on broadband terahertz generation based on ultrashort laser pumped AlGaAs multilayer heterostructure

  SUN Chang-Ming, LI Qiang-Shuang, DU Hai-Wei, WU Tao, FU Yan-Jun

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

  Abstract: (36) HTML (0) PDF (1.11 MKB)(40)

  Abstract:

  Semiconductor heterostructures have great ability to bind carriers and the potential to produce high power terahertz radiation. However， the intensity of terahertz radiation was substantially reduced， due to the interference effects of incoherent oscillations of plasma in the heterostructure. Thus in the AlGaAs ） multilayer heterostructure， it is able to adjust the absorption coefficient of the narrow band-gap layer by adjusting the aluminum molar fraction， which makes the excitation carriers number in each narrow band-gap layer approximately the same， achieving the goal of almost completely eliminating the interference effects. Based on the AlGaAs multilayer heterostructure terahertz radiation model， the properties of broadband terahertz radiation are studied with the numerical calculations， the quantitative relationships between the pump laser pulse width and the generated terahertz pulse are obtained， and the influence of pump laser pulse parameters on the parameters of generated terahertz puse are also analyzed. This study provides a good theoretical reference for the development of broadband terahertz radiation sources based on the semiconductor.

红外材料与器件

• Design and fabrication of 40Gbit/s error-free high-speed 850nm VCSEL Using NRZ modulation

  TONG Hai-Xia, WANG Yan-Jing, JIANG Ning, TIAN Si-Cong, TONG Cun-Zhu, WEI Zhi-Peng, WANG Li-Jun

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

  Abstract: (27) HTML (0) PDF (1.48 MKB)(44)

  Abstract:

  850 nm vertical cavity surface-emitting lasers are the core light source of the short-range optical interconnect. With the increasing demands for data center traffic, achieving NRZ modulated high speed error-free transmission is a current research hot topic. This paper designed and fabricated a high-speed 850 nm vertical cavity surface-emitting laser with six oxide limiting layers in a λ/2 short cavity. At room temperature, the -3 dB bandwidth up to 23.8 GHz. Clear eye diagrams were obtained under the test conditions of 50 Gbit/s (1 m) and 40 Gbit/s (100 m). Transmission tests showed that error-free transmission was achieved at transmission distances of 1 m and 100 m and transmission rates of 40 Gbit/s and 30 Gbit/s, respectively, by NRZ modulation without the use of pre-emphasis, equalization, and forward error correction.

太赫兹与毫米波技术

• A Dual-Polarized Active Phased Array Module for 5G Millimeter-Wave Communications

  Zhu Yuanwei, Yu Chao, Lu Rong, Hong Wei

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

  Abstract: (40) HTML (0) PDF (2.91 MKB)(66)

  Abstract:

  A dual-polarized active phased array antenna module is presented for 5G millimeter-wave communications. The array antennas and multi-channel beamforming chips are printed and implemented on the top and bottom layers of the multilayer PCB (2 mm thickness), respectively. Besides the interconnection of the antenna and chip, power supply and digital control are realized within the middle layers of the multilayer PCB. The measured results show that beam-scanning range larger than ± 40 degree (power level declines smaller than 3 dB) and normalized cross-polarization level small than -18 dB are both achieved in E- and H-planes. Besides 42.6-45.7 dBm and 43.5-46.1 dBm transmitting equivalent isotropically radiated powers (EIRPs) for V polarization and H polarization are realized respectively.

红外材料与器件

• Dewar vacuum lifetime estimate based on Langmuir adsorption model

  FAN Cui, WANG Xiao-Kun, JI Peng, ZHANG Lei, YU Jun, SHEN Yi-Zhang, MO De-Feng, LI Xue

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

  Abstract: (59) HTML (0) PDF (823.72 KKB)(37)

  Abstract:

  The main cause of vacuum failure is internal material outgassing. The Langmuir adsorption model outgassing equation was used to the calculation of vacuum lifetime in this pape because of the outgassing mechanism and the long-term degassing procedure of infrared detector dewar. The innovative method which changing the temperature at the end of degassing procedure was proposed to obtain outgassing activation energy. The outgassing rate measured at different temperatures while at the same time， removed the influence of coverage on the outgassing rate. The outgassing rates at storage temperature and the rule of outgassing rate change with time was deduced. The difference among three dewar outgassing activation energy obtained in different conditions is 8.8% . The heat load of the dewar was tracked for 2 years to verify the method. The estimated vacuum lifetime error of the Dewar is 7.2%. It is a non-destructive testing estimation method for the vacuum life of small amount and diversified Dewars.

太赫兹与毫米波技术

• Characterization of electrical parameters of high-purity quartz glass in the 40-110 GHz frequency band

  ZHU Xiang-Bao, SUN Xu, YUE Hai-Kun, QIAN Ling-Xuan, Ni Lei

  DOI:

  Abstract: (35) HTML (0) PDF (937.10 KKB)(33)

  Abstract:

  The transmission line structures such as coplanar waveguide (CPW) and microstrip ring resonator (MRR) were designed on a high-purity quartz substrate (99.9997%) with a thickness of 127 μm. The average insertion loss for the CPW line varied from 0.096 to 0.176 dB/mm in the frequency range of 40-110 GHz. Furthermore, the permittivity and loss tangent of the quartz was extracted by the MRR method. The permittivity of the quartz substrate in the V-band and W-band ranged from 3.7-3.85 and 3.85-4, respectively. The loss tangent value was approximately 0.004 in the V-band and 0.004-0.006 in the W-band. The performance comparison with other substrates shows that this high-purity quartz has excellent and stable electrical properties and its potential for designing high-performance passive and packaging structures.

遥感技术与应用

• Analysis of Eliminating Feature Mismatch in Satellite-Borne Optical Remote Sensing Images

  Xue Sumei, Tang Yuyu, Wei Jun, Huang Xiaoxian

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

  Abstract: (34) HTML (0) PDF (2.44 MKB)(15)

  Abstract:

  Mismatch elimination is an important means of improving the accuracy of feature matching. Due to the large amount of data, texture duplication, light intensity changes, and other characteristics of satellite-borne optical remote sensing images, the performance of existing mismatch elimination methods is degraded. To solve this problem, a method based on local and guided global geometric constraints is proposed to eliminate mismatches. Based on the initial matching set, local consistency of features is used to filter out mismatches. Then, according to the transformation relationship between images, a feature topological structure is constructed, and its geometric attributes are extracted to describe structural similarity. Based on this, a feature global structure consistency constraint model is established, and residual mismatches are eliminated by deriving the optimal solution of the model. A guided matching strategy is adopted for global constraint, and matching points with high local consistency are selected to form a high internal point rate matching set, which is applied as the feature global neighborhood to improve the robustness and efficiency of the algorithm. The experimental results show that, in comparison with existing methods, the proposed method has better matching performance for satellite-borne optical remote sensing images, with an average accuracy and recall of 0.9 and 0.89 respectively. It is robust on the initial matching set with different internal point rates, and the average F score is 0.86.

图像处理及软件仿真

• Sub-Pixel Mapping Based on Spectral Information of Irregular Scale Areas for Hyperspectral Image

  WANG Peng, CHEN Yongkang, ZHANG Gong, WANG Hongying, ZHAO Chunlei Zhao

  DOI:

  Abstract: (21) HTML (0) PDF (2.92 MKB)(20)

  Abstract:

  Sub-pixel mapping technology can analyze mixed pixels and realize the transformation from fractional images to fine a land-cover mapping image at the sub-pixel level. However, the spectral information used by the traditional sub-pixel mapping methods is usually constructed in a specified rectangular local window, and the spectral information of all bands is rarely used, affecting the performance of sub-pixel mapping. To solve this issue, sub-pixel mapping based on spectral information of irregular scale areas (SIISA) for hyperspectral image is proposed in this paper. The experimental results on three remote sensing images show the proposed SIISA outperform the existing sub-pixel mapping methods.

• Registration Method of Far Infrared Aerial Images based on sMLD Feature

  Guo Fan, Li Xiaohu, Zhu Hong, Tang Jin

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

  Abstract: (30) HTML (0) PDF (2.11 MKB)(36)

  Abstract:

  Accurate, robust, and fast feature representation and automatic registration are urgent need for far infrared image in aerial scenes. Since the existing Multiple Line Descriptors (MLD) has the problems of “isolated feature” and “limited scale transformation”, thus a feature description methods that combines feature points and line descriptors partition statistics is proposed. This paper refers to the feature descriptor as the Segmented MLD (sMLD). Combing the characteristics that sMLD feature connect with each other to form a mesh topology structure, a coarse-to-fine branch accelerated matching (RF-BA) algorithm is also proposed. The RF-BA coarse matching improves the matching efficiency by making full use of the topology structure and local optimal algorithm. The RF-BA fine matching improves the registration accuracy by using the minimum circumscribed convex quadrilateral principle and GMS verification principle. Experimental results show that compared with other existing registration methods, the method has better performance in terms of registration accuracy and running time.

红外材料与器件

• A novel ring-shaped top-DBR etched microstructure VCSEL with a hollow beam

  PANG Chao, YAN Chang-Ling, YANG Jing-Hang, QIAN Ran, LI Yi-Fei

  DOI:

  Abstract: (41) HTML (0) PDF (1.04 MKB)(37)

  Abstract:

  The structure of a novel ring-shaped top-DBR etched microstructure VCSEL with a proton implantation high resistance region was designed. A ring column structure was formed from the upper electrode to the active region, which directly generated a hollow laser beam output. The optical field distribution of the etched microstructure VCSEL was calculated by FDTD software, and the obtained ring-shaped patterns maintained the hollow beam characteristics under the different mode numbers. We fabricated the etched microstructure VCSEL with a lasing wavelength of 848 nm at room temperature and investigated its performance. The threshold current was 0.27 A and the peak power was up to 170 mW. The near-field patterns of different currents clearly displayed hollow ring-shaped spots. The distribution curves of far-field light intensity matched the characteristics of a hollow beam as well. This novel VCSEL provides a new approach for the development of hollow beams and even array devices.

• NIR-driven large modulation depth terahertz modulator based on silver/carbon nanoparticles

  GOU Hanguang, ZHU Yu, WU Zongdong, SHI Guanghua, LAI Weien

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

  Abstract: (25) HTML (0) PDF (843.28 KKB)(39)

  Abstract:

  Near-infrared light-driven terahertz modulators are an important component in terahertz/infrared fiber-optic hybrid communication systems. Here， a near-infrared driven terahertz modulator based on silver nanoparticles/carbon quantum dots （Ag NPs/CDs） is proposed. Experimental results show that the combination of silver nanoparticles （Ag NPs） and carbon quantum dots （CDs） induces quantum size effect and dielectric confinement effect of nanoparticles， and the absorption of NIR light by silicon substrate can be enhanced by using Ag NPs/CDs to achieve NIR-driven terahertz wave modulation. The terahertz transmission characteristics of the sample were characterized in the range of 0.22-0.33 THz with the 808 nm NIR modulation excitation source， and the modulation depth of the Ag NPs/CDs NIR terahertz modulator can reach about 83% compared with the reference silicon substrate， which is significantly higher than the modulation depth of the reference silicon substrate （~54%）， realizing the terahertz wave modulation with large modulation depth. This research work has important applications in terahertz/infrared fiber hybrid communication systems.

• Wavelength extended InGaAsBi p-i-n photodetector lattice-matched to InP

  Feng Duo, Dai Jin-Meng, Cao You-Xiang, Zhang Li-Yao

  DOI:

  Abstract: (40) HTML (0) PDF (1.89 MKB)(29)

  Abstract:

  InGaAs photodetector is widely used in SWIR detection. Bi incorporation into InGaAs can reduce the bandgap, extending the detection wavelength. With controlling of the In and Bi compositions, the detection wavelength could be extended to over 3μm from InyGa1-yAs1-xBix, lattice-matched to InP. An In0.394Ga0.606As0.913Bi0.087 p-i-n photodetector is designed and its performance is numerically investigated. Dark currents and responsivity spectra are calculated with different temperatures, absorption layer thicknesses and doping concentrations. A 50% cut-off wavelength of 3μm is achieved. The proposed structure provides a feasible way to fabricated InGaAsBi based SWIR detector with longer detection wavelength.

• The 760nm-vertical cavity surface emitting laser for the oxygen sensing

  LIU Tian-Jiao, XU Yue-Hui, ZHANG Jian-Wei, ZHANG Xing, ZHANG Zhuo, GONG Yu-Xiang, ZHOU Yin-Li, MU Jing-Fei, CHEN Chao, WU Hao, NING Yong-Qiang, WANG Li-Jun

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

  Abstract: (92) HTML (0) PDF (1.30 MKB)(44)

  Abstract:

  A 760 nm single-mode， wavelength-tunable Vertical Cavity Surface-Emitting Laser （VCSEL） for oxygen sensing has been reported， and the design method and device fabrication results of the 760 nm VCSEL has been reported in detail. By analyzing the gain characteristics of AlGaAs quantum wells， the composition and thickness of the quantum wells were determined， and the VCSEL structure with a gain peak and cavity mode mismatch of 10 nm at room temperature was designed. The single-mode power of the VCSEL exceeds 2 mW when the operating temperature is 25°C， the side-mode suppression ratio （SMSR） is 28.1 dB， and the full angle of the divergence angle is 18.6°. As the operating current increases， the divergence angle of the VCSEL laser increases， but the far-field is still a circular and symmetrical spot with a Gaussian shape. By tuning the operating temperature and operating current of the VCSEL laser， the single-mode wavelength of VCSEL can be continuous tuned from 758.740 nm to 764.200 nm. The current tuning coefficient of the laser wavelength changes from 1.120 nm/mA to 1.192 nm/mA and the temperature tuning coefficient changes from 0.072 nm/° C to 0.077 nm/° C when the VCSEL operates at 15-35°C. The side- mode suppression ratios of VCSEL laser reaches 32.6 dB and 30.4 dB near the two characteristic absorption wavelengths of oxygen.

• Research of performance grade and development route of image intensifiers

  LIU Yu, SHI Lihui

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

  Abstract: (32) HTML (0) PDF (720.59 KKB)(19)

  Abstract:

  A method for judging the performance of image intensifiers is described used for night vision devices. Based on operating distance model， some factors affecting the detection ability are analyzed. The difference between test conditions for integral sensitivity， ultimate resolution and actual night vision environment are studied. The influence of night sky radiation spectral characteristics， spectral attenuation characteristics of atmospheric transmission， and spectral difference of background reflection characteristics on detection distance are analyzed. The shortcomings of traditional methods for judging quality of the image intensifiers are sorted out. “Figure of Capability” （FOC） is proposed， which is consists of signal-to-noise ratio， resolution tested in low illumination and low contrast， and technical features. The performance echelon and intergenerational of two major technology routes （including GaAs tubes and multi-alkali tubes） are analyzed with FOC， and one kind of Gen. 3^rd development route is designed. Experimental results show that FOC can accurately reflect the development law of the technical route and grade of image intensifiers.

太赫兹与毫米波技术

• Design of W-band high-order mode extended interaction klystron based on novel multi-gap cavity

  XIE Bing-Chuan, ZHANG Rui, WANG Huan-Huan, WANG Yong, GENG Zhi-Hui, LIAO Yun-Feng, YANG Xiu-Dong

  DOI:

  Abstract: (23) HTML (0) PDF (1.58 MKB)(57)

  Abstract:

  A novel resonator has been proposed for klystron that operates at TM₃₁₀ mode. The electric fields of both the middle cavity and the side cavity are effectively enhanced by discretizing the field in the side cavity. The novel resonator demonstrates a higher characteristic impedance than the traditional barbell shape cavity when both cavities operate at TM₃₁₀ mode. Sensitivity analysis has been performed on these two kinds of cavities. Moreover， an RF circuit in W-band has been designed based on the proposed novel cavity. The RF circuit can achieve a high gain of 52.4 dB and a peak output power of 7.8 kW when 45 mW input power is injected. The circuit is driven by a 25 kV and 2A pencil beam. The electronic efficiency and 3-dB bandwidth are 15.6 % and 120 MHz， respectively.

• High-efficiency AlN/GaN MIS-HEMTs with SiNx insulator grown in-situ for millimeter wave applications

  CHEN Xiao-Juan, ZHANG Yi-Chuan, ZHANG Shen, LI Yan-Kui, NIU Jie-Bin, HUANG Sen, MA Xiao-Hua, ZHANG Jin-Cheng, WEI Ke

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

  Abstract: (61) HTML (0) PDF (1.90 MKB)(174)

  Abstract:

  In this work， high-efficiency AlN/GaN metal-insulator-semiconductor high electron mobility transistors （MIS-HEMTs） have been fabricated for millimeter wave applications. A 5-nm SiN_x insulator is grown in-situ as the gate insulator by metal-organic chemical vapor deposition （MOCVD）， contributing to remarkably suppressed gate leakage， interface state density and current collapse. The fabricated MIS-HEMTs exhibit a maximum drain current of 2.2 A/mm at V_GS=2 V， an extrinsic peak G_m of 509 mS/mm， and a reverse Schottky gate leakage current of 4.7×10^-6 A/mm when V_GS = -30 V. Based on a 0.15 μm T-shaped gate technology， an f_T of 98 GHz and f_MAX of 165 GHz were obtained on the SiN/AlN/GaN MIS-HEMTs. Large signal measurement shows that， in a continuous-wave mode， the MIS-HEMTs deliver an output power density （P_out） of 2.3 W/mm associated with a power-added efficiency （PAE） of 45.2% at 40 GHz， and a P_out （PAE） of 5.2 W/mm （42.2%） when V_DS was further increased to 15 V.

• Correlation between MBE deoxidation conditions and InGaAs/InP APD performance

  GUO Zi-Lu, WANG Wen-Juan, CHEN Ping-Ping, LU Wei, WANG Xing-Jun, QU Hui-Dan, FAN Liu--Yan, ZHU Yi-Cheng, WANG Ya-Jie, ZHENG Chang-Lin

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

  Abstract:

  InP-based InGaAs/InP avalanche photodiodes (APDs) have high sensitivity to near-infrared light, making them ideal optoelectronic devices for weak signal and single-photon detection. However, as device structures become complex and advanced, with thickness and sizes ranging from nano to micro scales, performance is increasingly constrained by defects in the lattice of the material and the process conditions. Solid source molecular beam epitaxy (MBE) technology is used to deoxidize InP substrates under the atmosphere As4 and P2, respectively, and epitaxially grow lattice-matched In0.53Ga0.47As film and InGaAs/InP avalanche APD full-structure materials. The experiment results demonstrate that As4 deoxidation protection has distinct advantages over P2 deoxidation atmosphere in terms of InGaAs materials based on InP substrates, which can make a straight and sharp heterojunction interface, lower carrier concentrations, higher Hall mobilities, longer minority carrier lifetimes, and achieve suppression of dark current caused by point defects or impurity defects in the device. Therefore, As4 deoxidation can be applied effectively to enhance the quality of MBE materials. This work optimizes InP substrate InGaAs/InP epitaxial growth parameters and device fabrication conditions.

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• G-band Quad-port Balanced Multiplier with 111.27mW Continuous-wave Output Power

  HUANG Kun, YANG Hao, LI Ruo-Xue, ZHOU Ren, JIANG Jun, HE Yue, Tian Yao-Ling

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

  Abstract:

  A 215-230GHz Schottky varactor-based frequency doubler utilizing novel four-port balanced configuration has been developed with improved conversion efficiency and power-handling capability. The proposed doubler, featuring doubled number of anodes in conventional balanced ones, could inhibit the odd- and fourth-order harmonics. Thus, better conversion efficiency and doubled power handling capability could be achieved. At room temperature, the fabricated doubler exhibits a ~39.5% peak conversion efficiency (@218GHz) for an input power of 196~340mW, which is proved to be a perfect solution for the generation of high power terahertz waves even at higher frequencies.

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• Evaluation of observation quality of FY-3E/HIRAS-II using the innovation vector method

  ChenHongtao, Guan Li

  Abstract: (2) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  FY-3E/HIRAS-II is the first early mooring orbiting infrared hyperspectral instrument in the world. Evaluating the quality of its observation data plays a very important role in improving the data assimilation and the accuracy of global numerical weather prediction. Based on 35 days of HIRAS-II observations from December 2021 to January 2022 and March 2022, this paper uses the innovation vector method to assess the quality of the on-orbit observation data. The distribution characteristics of O-B deviation and standard deviation are calculated by land and ocean respectively. The results show that the O-B average deviation of long wave and medium wave in most channels is less than 0.5 K, and the standard deviation is within 1 K. The standard deviation on land is larger than that on ocean (especially for window channels). Due to the deviation of ERA5 reanalysis data, the radiation value simulated by RTTOV has systematic error in the 664~665 cm-1 CO2 absorption band and 1300~1680 cm-1 water vapor absorption band, which makes the deviation larger; The large deviation near the 980-1080 cm-1 O3 absorption band and 1300 cm-1CH4 absorption band is caused by the use of fixed climate profile values in RTTOV. The O-B average deviation of short wave in most channels is between – 2 K and 2 K, and the standard deviation is within 2 K. The channels near 1920cm-1 are the junction of medium wave and short wave of the instrument, so different detectors will cause large O-B deviation. The large deviation of 2267~2380 cm-1 is due to the fact of the NLTE effect (Non-local Thermodynamic Equilibrium) is not taken into account when RTTOV simulates the brightness temperature. The deviation and standard deviation of channels greater than 2400 cm-1 increase gradually due to solar pollution. HIRAS-II O-B deviation is asymmetric with the scanning angle, so it is necessary to correct the scanning angle deviation when using HIRAS-II data.

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• Single mode terahertz quantum cascade lasers based on distributed Bragg reflector

  BAI Hong-Zhou, ZANG Shan-Zhi, TAN Cheng, WANG Kai, GAN Liang-Hua, XU Gang-Yi

  Abstract: (1) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  In the conventional semiconductor distributed Bragg reflector (DBR) lasers, to obtain stable single mode emission, the gain section should be short enough to make the free spectrum range larger than half of the bandwidth of the reflection plateau caused by the DBR. This constraint severely limits the threshold and the output power of the lasers. In this work, we realized single mode terahertz DBR quantum cascade lasers (THz-DBR-QCLs) that broke the above constraint. The lasers are based on the ridge waveguide, and exploit a cleaved facet and a DBR mirror to construct the resonator. Exploiting the intrinsic narrow gain spectrum of the THz-QCL, we tailor the reflection spectrum of the DBR so that the high reflection plateau and the gain spectrum are partially overlapped. Such strategy enables single mode emission with a significantly elongated gain section, far beyond the constraint of the free spectrum range. In experiments, we realized single mode THz-DBR-QCLs, whose gain section is as long as 3.6 mm. The emission frequency is about 2.7 THz, and the side mode suppression ratio (SMSR) exceeds 25 dB. The measured threshold and temperature characteristics of the THz-DBR-QCLs are comparable to the Fabry-Perot THz-QCLs fabricated with the same material. Our work suggests a novel approach to realize high performance single mode THz-QCLs.

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• Nonlinear response correction method for on-orbit data of FY-3E hyperspectral infrared atmospheric sounder II

  huangshuo, GU Ming-Jian, HU Yong, YANG Tian-hang, SHAO Chun-Yuan, ZHANG Chun-Ming

  Abstract: (2) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The Infrared Hyperspectral Atmospheric Sounder II (HIRAS-II) mounted on Funyun-3E satellite (FY-3E) can realize vertical atmospheric detection, featuring hyperspectral, high sensitivity and high precision. When the satellite has been on-orbit, nonlinear response would occur due to instrument attenuation and environmental change, which affects the accuracy of on-orbit calibration. For nonlinear response problems, a nonlinear correction method based on in-band spectrum is proposed. Firstly, the nonlinear correction coefficient was solved based on the nonlinear characteristics of the out-of-band in low-frequency spectrum, and the coefficient was input into the radiological calibration model as the initial value. The deviation between the black-body spectrum measured on board and the ideal spectrum was taken as the objective function, and the nonlinear correction coefficient was optimized by iterative calculation. Radiation calibration experiments show that the blackbody brightness temperature deviation of the proposed method is significantly lower than uncorrected result and the out-of-band correction method. Based on the simultaneous nadir overpass method, After matching the observed data of HIRAS-II with IASI and calculating the mean brightness temperature deviation and the absolute value of the deviation, the mean brightness temperature deviation after nonlinear correction by the in-band correction method is -0.13K, which is better than the out-of-band correction method.

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• Recent Advances in On-chip Infrared Polarization Detection

  ZHEN Yu-Ran, ZHOU Jing

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

  Abstract:

  Polarization is an intrinsic degree of freedom of light. The detection of polarization light provides more information in addition to light intensity and wavelength. Infrared polarization detectors play a vital role in numerous applications, such as imaging, communication, remote sensing, and cosmology. However, traditional polarization detection systems are bulky and complex, hindering the miniaturization and integration of polarization detection. Recently, the development of on-chip infrared polarization detectors has become an area of great interest. In this review, we focus on two recent advanced research areas of on-chip infrared polarization detectors: polarization-sensitive materials and integration of polarization-selective optical coupling structures. We discuss the current research status, future challenges and opportunities for the development of on-chip infrared polarization detectors.

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• Study on photocurrent and quantum efficiency of interband cascade infrared photodetectors

  BAI Xue-Li, CHAI Xu-Liang, ZHOU Yi, ZHU Yi-Hong, LIANG Zhao-Ming, XU Zhi-Cheng, CHEN Jian-Xin

  Abstract: (12) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The interband cascade infrared photodetector (ICIP) can achieve high operating temperature by using the multistages cascade absorption region. But different design of absorption region will cause the mismatch of photogenerated carriers, which will affect the quantum efficiency of the device. In order to better understand the influence of the stages and thickness of ICIP on quantum efficiency, we measured the performance of ICIP based on type-II InAs/GaSb superlattice at different operating temperature. And based on the “average effect” of photocurrent, a quantum efficiency model operating at reverse bias voltage is established. Compared with the measured results, it is found that the experimental data and the calculated results are in good agreement at low temperature. It is verified that the photocurrent is the average of current at all stages based on the electrical gain. However, the experimental photocurrent at high temperature is lower than the calculation. This may be due to the short minority carrier lifetime at high temperature, and the photogenerated carrier recombination mechanism exists at the interface of the absorption region and the relaxation region.

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• Ultra-broadband terahertz generation from few-cycle laser pulse interaction with gas plasma filament

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

  Abstract: (6) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Strong few-cycle laser pulse interaction with the gas plasma filament can generate strong and broadband terahertz radiation. Here, we investigate the detail of plasma current and its terahertz radiation produced by the few-cycle laser pulse interaction with the gas plasma based on the calculations. The ionization during the plasma filamentation is in the transition between the tunnel ionization and the multiphoton ionization. The results show that this scheme can generate ultra-broadband terahertz pulse with frequency up to several tens of terahertz, and the amplitude of terahertz pulse is the period function of carrier-envelope phase of the few-cycle laser pulse. The frequency of terahertz pulse is determined by the duration of the laser pulse, the time evolution of the ionization and the plasma current, but not the density of the plasma. This work might give a useful clue to carry out the experiment of terahertz generation from the few-cycle laser pulse interaction with the gas plasma filament.

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• An unsupervised few-shot infrared aerial object recognition network based on deep-shallow learning graph model

  LI Yu-Ze, ZHANG Yan, CHEN Yu, YANG Chun-Ling

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

  Abstract:

  In the field of military aerial object recognition, due to the lack of samples, current artificial intelligence algorithms cannot perform well. This paper uses the existing sufficient auxiliary domain images to assist the application domain with few samples for cross-domain object recognition and solves the problem of weak generalization ability and poor recognition performance of the recognition model caused by the lack of label information and sparse samples. A cross-domain object recognition algorithm named Deep-Shallow Learning Graph Model (D-SLGM) is proposed. Firstly, a deep-shallow two-stream feature extraction algorithm is proposed to solve the problem of feature representation under unsupervised few-shot conditions. At the same time, a feature fusion algorithm based on graph model is proposed to realize high precision fusion between features. Then, a recognition model is trained based on the fused features, the generalization ability of object recognition algorithm is improved. The self-built aerial object dataset is adopted with three application scenarios. The experimental results show that the mean average recognition accuracy of D-SLGM reaches 78.2 %, which is better than the comparison methods and has great application potential in actual aerial object recognition applications.

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• Coronene enhanced CMOS image sensor

  LUO Lei, SONG Li-Yuan, Tang Li-Bin, WANG Shan-Li, CAI Yu-Hua, LI Jun-Bin

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

  Abstract:

  The responsiveness of typical silicon-based CMOS image sensors in the UV band is barely since the limited penetration depth of UV light in silicon and the absorption of polysilicon gates by UV light. A low-cost down-conversion method was used in this work to enhance the UV response of a CMOS image sensor. Vacuum thermal evaporation was used to deposit coronene films on quartz substrates and CMOS image sensors, respectively. The films' optical characteristics, infrared spectrum, light stability, and thermal stability were investigated. The experimental results reveal that the Coronene coating absorbs UV light and emits green fluorescence at 500 nm, which closely matches the spectral response peak of the CMOS image sensor. At the same time, it is found that the experimental value of infrared absorption spectrum of Coronene is in good agreement with the calculated value, and the fluorescence intensity of the emission peak of the film remains 95.7% after annealing at 200 ℃ for 20 minutes. After approximately 60 minutes of exposure at 280 nm excitation wavelength, the fluorescence intensity decreased exponentially to 64% of the initial value. The UV enhancement effect of the film was qualitatively analyzed by using CMOS monochromatic camera under visible light (400-780nm) and ultraviolet light (365nm) radiation. It is found that the sensitivity of the CMOS monochromatic camera to UV light can be improved after the deposition of Coronene film.

  • 1
• Studies of resonator-enhanced mid-infrared interband cascade light emitting diode

  ZHANG Wang-Lin, CHAI Xu-Liang, ZHOU Yi

  Abstract: (8) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The mid-infrared light emitting diodes based on interband cascade structure and resonant cavity structure are simulated and designed. Based on the traditional interband cascade LED, a distributed Bragg reflector (DBR) structure is introduced outside the device to form a resonant interband cascade LED. The parameters of the resonant cavity are simulated and optimized, including the number of DBR cycles, the length of the resonator, the position of the active region in the resonator, and the optimized device structure is obtained. Simulation results show that the device using ZnS/Ge DBR with one period as the upper mirror of the resonator has the highest output power. When the active region is located at the peak of the electric field intensity in the resonant cavity, the device will have the highest output power. The output power of the three-stage resonant cavity interband cascade LED device is equivalent to that of the 55-stage device without resonant cavity. Meanwhile, the output light has better directionality, and the full width at half peak of the far field distribution can be reduced from 92 degrees to 52 degrees. Combined with the test results of the fabricated 5-stage interband cascade LED device, the simulation results after adding a resonant cavity structure indicate that the radiance of the peak wavelength is increased by 11.7 times, the integrated radiance is increased by 5.43 times, and the full-width at half-maximum is narrowed by 6.45 times.

  • 1
• Analysis of the operating distance of an infrared polarimetric imaging system considering the non-ideality of the detector

  TAN Chang, WANG Shi-yong, GAO Si-li

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

  Abstract:

  Abstract: To compare the detection capabilities of traditional infrared imaging systems and infrared polarization imaging systems, models for the operating distance of each system were established based on the minimum resolvable temperature difference and the minimum resolvable polarization degree difference. The effects of parameters of non-ideal detectors on the detection capabilities of the systems were discussed, and corresponding experiments were designed to verify the reliability of the established models. This provides a reference for the selection of imaging systems in different application scenarios in actual detection.

  • 1
• Faraday rotation in nitrogen-doped single crystal diamond measured by polarized terahertz time-domain spectroscopy in the presence of strong magnetic field

  XIAO Huan, WEN Hua, XU Wen, ZHANG Jing, CHENG Xing-Jia, XIAO Yi-Ming, DING Lan, LI Hao-Wen, CHENG Yan-Zhe, HE Bin, Francois M. Peeters

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

  Abstract:

  Nitrogen (N) doped single crystalline diamond (N-SCD) is one of the most important carbon-based electronic materials and has many interesting and unique features in terms of physics owing to the presence of N related color centers. In this paper, the terahertz (THz) magneto-optical (MO) physical properties of N-SCD grown by plasma chemical vapor deposition (MPCVD) are studied. By using polarized THz time-domain spectroscopy (TDS) in the presence of magnetic field from 0 to 8 T, the THz transmission through N-SCD in Faraday geometry is measured at 80 K. The variation patterns of Faraday rotation angle and ellipticity, and complex transverse or Hall MO conductivity with magnetic field for N-SCD are obtained. The results show that N-SCD has excellent THz MO Faraday rotation effect.

  • 1
• Ultra-high detection efficiency InGaAsP/InP single photon avalanche diodes at room temperature

  QI Yu-Fei, WANG Wen-Juan, SUN Jing-Hua, WU Wen, LIANG Yan, QU Hui-Dan, ZHOU Min, LU Wei

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

  Abstract:

  We described a high-performance planar InGaAsP/InP single-photon avalanche diode (SPAD) with a separate absorption, grading, charge and multiplication (SAGCM) heterostructure. By electric field regulation and defects control, the SPAD operated in the gated-mode at 293 K with a photon detection efficiency (PDE) of 70%, a dark count rate (DCR) of 14.93 kHz and an after-pulse probability (APP) of 0.89%. Furthermore, when operated in the active quenching mode with a dead time of 200 ns, a PDE of 12.49% and a DCR of 72.29 kHz were achieved at room temperature.

  • 1
• The photon detection mode and performance analysis of SIPM photon counting Lidar under different discrimination thresholds

  Liu Xin-yuan, Xiao Yi, MA Yue, Xiang Yu-yan, Guo Gao-feng, Wang Jia-wei, Huang Wei-yi, Tan Chong-tao, LI Song

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

  Abstract:

  Silicon photomultiplier (SiPM) is a silicon array structure based on Geiger mode avalanche photodiode. It not only has extremely high photon counting sensitivity and response speed, but also has the characteristics of high dynamic range and linear response under the multi-photon condition, which makes it have unique advantages in the application of photon counting LIDAR. However, due to the multi-pixel, single-time channel working mode of SiPM, its output voltage has a greater probability of pulse pile up compared with other single-photon detectors. Therefore, the detection process of SiPM under different discrimination thresholds is more complicated. To solve this problem, a SiPM photon event response model is established in this paper. Based on this, the time-domain distributions of the shielding effect and the triggering effect caused by pulse pile up are discussed. Finally, the semi-analytic detection probability and false alarm probability models of SiPM are established. At the same time, a photon counting LIDAR system based on SiPM detector was built, and the theoretical model was verified by observing that the measured output voltage waveform and point cloud distribution were consistent with the theoretical model (R2^>0.95). Furthermore, the distribution of SiPM photon point cloud with different discrimination thresholds is quantitatively evaluated by the recall and precision ratio, and the optimal discrimination threshold interval is given, which has important guiding significance for the design and theoretical analysis of photon counting LIDAR system based on SiPM.

  • 1
• A whole chain automatic simulation method for the on-orbit stray light effect of optical payloads

  YIN Kai, NIU Xin-Hua, ZHANG E

  Abstract: (9) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The temperature inversion inconsistency phenomenon is analyzed for the on-orbit IR calibration of Visible and InfraRed Radiometer (VIRR) which is a payload onboard polar-orbiting meteorological satellite FY-3C. A specific methodology, i.e., the whole chain automatic simulation and analysis, is proposed. This method involves the orbital parameters and the satellite platform environment. By means of the ray trace of the opto-mechanical structure with high precision, the quantified effect of solar stray light are obtained. The simulation includes on-orbit IR calibration and solar incidence, resulting in the identification of the incidence path of solar stray light as well as the explanation for the temperature inversion inconsistency. Through the comparison between the simulated results and the on-orbit data of satellite, the effectiveness and the validity of the method is verified. This method can be applied to the simulation and analysis of on-orbit stray light effect of the same-typed payloads. This work can also provide reference to the recalibration of historical data.

  • 1
• Study on Material Characterization and Device Performance of Non-uniform GaAs/AlGaAs Quantum Well Infrared Detectors

  SU Jia-Ping, ZHOU Xiao-Hao, TANG Zhou, FAN Liu-Yan, XIA Shun-Ji, CHEN Ping-Ping, CHEN Ze-Zhong

  Abstract: (40) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  In this paper, the GaAs/AlGaAs non-uniform quantum well infrared detector material was successfully grown by molecular beam epitaxy (MBE), and the microstructure was characterized in detail. The performance difference between the non-uniform quantum well structure and the conventional quantum well infrared detector is analyzed and compared, and the performance change of the non-uniform quantum well infrared detector under different well widths is comparatively studied. The microstructure of non-uniform quantum well infrared detector materials was analyzed by high resolution transmission electron microscopy (HRTEM) combined with energy dispersive spectroscopy (EDS), and the non-uniform well doping was characterized by secondary ion mass spectrometry (SIMS). The results show that the crystal quality of the non-uniform quantum well epitaxial material is very good, and the non-uniform quantum well structure and doping concentration are also in good agreement with the design values. The unit quantum well infrared detector has been successfully fabricated. The research results show that for non-uniform quantum well infrared detectors, the electric field distribution of the quantum well can be changed by changing the doping concentration and barrier width of each well. Compared with traditional uniform quantum well infrared detectors, their dark current significantly decreases (by about an order of magnitude). Moreover, under different well widths, the transition modes of non-uniform quantum wells can change, and devices with bound state to quasi-bound state transition modes (B-QB) have better blackbody response and lower dark current.

  • 1
• Enhancing terahertz waves generation in air-plasma induced by femtosecond three-color harmonic pulses

  Wang Han-Qi, Fan Wen-Hui, Chen Xu, Yan Hui

  Abstract: (9) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Terahertz waves generation from air-plasma induced by femtosecond three-color harmonic pulses with frequency ratio of 1:2:m (m is a positive integer), based on the transient photocurrent model and the sawtooth-like electric field formed via multi-color harmonic pulses superposition, has been theoretically investigated. It can be seen even in the case of air is saturated ionized and the electron density reaches the same maximum, for the same number of harmonic pulses, THz conversion efficiency is not always higher when the electric field shape in the composed pulse envelope is closer to sawtooth waveform and more asymmetric. Besides, the specific wavelength combination schemes of femtosecond three-color harmonic pulses with the frequency ratios of 1:2:3 and 1:2:4 have also been simulated, which can significantly enhance terahertz waves generation, and are realized by adding only a set of optical parametric amplifier on the basis of the conventional two-color laser pulses case at the frequency ratio of 1:2. Our study will be helpful to obtain intense terahertz source and provide guidance for experiment operation.

  • 1
• Clinical Advances on Fluorescence Imaging in the Second Near-Infrared Window

  NI Hu-Wei, QIAN Jun

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

  Abstract:

  Near-infrared fluorescence bioimaging is a vital technology that enables image-guided surgery. In recent years, the maturation of the optical bioimaging theory in the second near-infrared window (NIR-II, 900-1700 nm) has led to the emergence of NIR-II fluorescence imaging as a significant research area in imaging-guided surgery. This paper provides a succinct overview on the current development state of NIR-II fluorescence probes and imaging systems based on the NIR-II optical bioimaging theory. Furthermore, it reviews the studies conducted on NIR-II fluorescence imaging in small animal and clinical surgery, and discusses the potential and challenges of this technology in clinical surgery, including the difficulties that need to be addressed in future clinical translation.

  • 1
• Effects of Gamma Irradiation on Performance of InGaAsP/InP Single-photon Avalanche Diodes

  SUN Jing-Hua, WANG Wen-Juan, ZHU Yi-Cheng, GUO Zi-Lu, QI Yu-Fei, XU Wei-Ming

  Abstract: (9) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  InGaAsP/InP single-photon avalanche diodes (SPADs) were gamma-irradiated with total doses of 10 k and 20 krad (Si) and tested in situ and shift methods. After irradiation, the dark currents and dark count rates were degraded slightly, whereas the photon detection efficiency and the afterpulse probability were basically unchanged. After a certain period of annealing at room temperature, these degradations were essentially recovered, indicating that transient ionization damage dominated in the gamma irradiation of InGaAsP/InP single-photon avalanche diodes.

  • 1
• Surface potential alignment in MoS2 and MoTe2 homo- and hetero-junctions

  JIANG Cong, ZHANG Shuai-Jun, LI Yu-Ying, WANG Wen-Jing, XIA Hui, LI Tian-Xin

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

  Abstract:

  In transition metal dichalcogenides (TMD) flakes, the geometry, such as layer thickness, significantly tune the electronic properties, including bandgap, electron affinity and Fermi level. Such characteristic offers a high degree of freedom to tune the functionality of semiconductor device, once the volatile electronic properties are precisely determined. However, to date, there are still significant uncertainties in determining the Fermi-level alignment of a TMD homo- or hetero- junction, which might lead to significant deviations of band-bending and thus device performance. Here, we utilize the Scanning Kelvin Probe Microscopy (SKPM) to characterize the surface-potential/Fermi-level alignment of TMD homo- or hetero- junctions. Through this effort, a distinct phenomenon is verified where the Fermi-levels of MoS2 and MoTe2 shift towards the intrinsic level with an increasing layer thickness (in other words, the background doping concentration is continuously lowering). Moreover, we show the significant impact of surface contamination (molecular scale) on the surface potential of monolayer TMD. Finally, we fabricate a MoTe2/MoS2 heterojunction, in which we observe the wide depletion region and large photoresponse. Together, those findings might offer a reference to precisely stack van der Waals(vdW) layers as designed for both electronic and optoelectronic applications.

  • 1
• High Performance and Broadband photodetectors Based on SnS2/InSe Heterojunction

  WANG Bing-Hui, XING Yan-Hui, HE Wen-Xin, GUAN Bao-Lu, HAN Jun, DONG Sheng-Yuan, LI Jia-Hao, FANG Pei-Jing, HAN Zi-Shuo, ZHANG Bao-Shun, ZENG Zhong-Ming

  Abstract: (21) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  We reported a broadband photodetector with a spectral range of 365-965 nm, based on a SnS2/InSe vertical heterojunction. In this device, InSe serves as the optical absorption layer, effectively extending the spectral range, while SnS2 functions as the transmission layer, forming a heterojunction with InSe to facilitate separation of electron-hole pairs and enhance the responsivity. The photodetector exhibits a responsivity of 813 A/W under 365 nm. Moreover, it still maintained a high responsivity of 371 A/W, an external quantum efficiency of 1.3 × 10（5）%, a specific detectivity of 3.17 × 10（12） Jones, and a response time of 27 ms under 965 nm illumination. The above investigation provides a new approach for broadband photodetectors with high responsivity.

  • 1
• Novel local calibration optimization from soil mid-infrared spectral library

  SHEN Jia-li, CHEN Song-Chao, HONG Yong-Sheng, LI Shuo

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

  Abstract:

  Soil mid-infrared (MIR) can provide a rapid, non-polluting, and cost-efficient method for estimating soil properties, such as soil organic carbon (SOC). Although there is a wide interest in using the soil spectral library (SSL) for soil analysis at various scales, the SSL with a general calibration often produces poor predictions at local scales. Therefore, developing methods to ‘localise’ the spectroscopic modelling is a reliable way to improve the use of SSL. In this study, we proposed a new approach that aims to rapidly build the optimal local model from the SSL by calculating spectral similarity and developing local calibration, in order to further improve prediction accuracy. The distance matrix was constructed by three distance algorithms, namely Euclidean distance, Mahalanobis distance, and Cosine distance, which were compared and used to measure the similarity between the local samples and the SSL. The capacity curve, which was taken from the distance matrix, was used with a method called “continuum-removal” to find the feature points. Partial least-squares regression was used to build the spectroscopic models for SOC estimation. We found that for all three distance algorithms combined with the continuum-removal, the local calibration derived from the first feature point gave us a good idea of how accurate the prediction would be. The Mahalanobis distance can effectively develop the optimal local calibration from the MIR SSL, which not only achieved the best accuracy (R2 = 0.764, RMSE = 1.021%) but also used the least number of samples from SSL (14% SSL). On local scales, the approach we proposed can significantly improve both the analytical cost and the accuracy of soil MIR technique.

  • 1
• Research on Hyperspectral Image Classification Method Based on Deep Learning

  ZHANG Bin, LIU Liang, LI Xiao-Jie, ZHOU Wei

  Abstract: (23) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  To improve the classification accuracy of current hyperspectral image classification methods, this study presents a hyperspectral image classification method based on Spectral-spatial transformer (SST) network. Hyperspectral images are firstly preprocessed into one-dimensional feature vectors, and the SST classification network with spectral-spatial attention module (SSAM) and Pooling residual block (Pool ResBlock) are designed. Among them, the spectral-spatial attention module is used to capture the correlation between spectral channels and spatial positions. The pooled residual module adds a pooled layer before the residual module to extract the Patch global features on the spectral channels. Finally, maximum pooling and average pooling are adopted to further improve the model robustness. Overall accuracies of the presented method on Indian Pines data set and Pavia University data set are 98.67% and 99.87%, respectively, suggesting that the presented method achieves a satisfactory performance.

  • 1
• Effects of embedded low-dimensional materials on resonant mode of distributed Bragg reflector cavity

  CUI Zhuang-Zhuang, LIU Qing-Quan, XIE Mao-Bin, WANG Shao-Wei, LU Wei

  Abstract: (24) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Low-dimensional material embedded cavities have been widely used in nano-lasers and detectors etc. The effects of embedded materials on cavity resonant mode need to be intensively studied for achieving efficient coupling between the gain material and cavity. Influence of embedded material thickness and position, cavity layer thickness and number of distributed Bragg reflector pairs on cavity resonant mode are discussed in this work. Results show that cavity resonant mode changes periodically with different embedded positions and there is a maximum peak shift with in a period of λ/2 optical path. The maximum peak shift decreases with increasing cavity thickness and is proportional to embedded material thickness. The number of distributed Bragg reflector pairs does not affect cavity resonant mode. These results provide a guidance for optical device design and analysis of experimental phenomena, which can be applied to different wavelength ranges of distributed Bragg reflector cavity structures.

  • 1
• A Self-calibration Method of the Boresight Angles of Airborne Hyperspectral VNIR/SWIR Imager

  Guo, WANG Yue-Ming

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

  Abstract:

  External field-of-view (FOV) stitching is an effective way to achieve an airborne hyperspectral imaging system with both a large field-of-view and a wide spectral sampling range. However, due to the independent installation of each module, the boresight angles between the corresponding VNIR module and SWIR module will change after a long period of equipment operation, and the change of boresight angles will negatively affect the data fusion effect. The overlap of FOV makes the calibration method based on the epipolar geometry and homography constraints ineffective in solving the boresight angles between the corresponding VNIR/SWIR modules. In this paper, an algorithm based on reprojection error is proposed for an airborne hyperspectral imaging system with external field-of-view stitching to achieve self-calibration of the boresight angles and focal length between the VNIR/SWIR backends. The algorithm has been applied to the AMMIS. Experimental results show that the average error of the method is less than 0.1 pixel, and it is also well adapted to tilt-placed modules.

  • 1
• Wavelength tunable fiber laser for CARS imaging

  ZHAO Ming-Ze, LI Jia-Ying, LIU Liang, LI Dian-Dian, HAO Qiang, YANG Kang-Wen

  Abstract: (37) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Coherent anti Stokes Raman scattering (CARS) microscopy showed great potential in rapid pathological analysis, pharmacokinetics and other fields. However, the non-resonant background (NRB) signals generated during imaging will affect the detection of CARS signals. By tuning the wavelength, the signal can be generated at the coexistence of resonance and NRB, or at the place where there is only NRB. The influence of NRB can be eliminated to a certain extent by cancelling the two signals. In this paper, a wavelength tunable erbium-doped fiber laser system based on divided pulse amplifier and crystal frequency doubling was built. It was proposed to control the pump power of two-stage amplifiers to achieve wavelength tuning. Finally, 110.8 mW and 136 fs pulses were output at 779.1-784.5 nm, 777.5-786.1 nm and 784.5-790.5 nm. The laser and ytterbium-doped laser system can be used for CARS imaging through passive synchronization.

  • 1
• Study on spectral ellipsometry of SnTe nanofilm

  SONG Li Yuan, Tang Li bin, Wang Shan Li, Hao Qun, Kong Ling de, Li Jun bin

  Abstract: (27) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The accurate acquisition of optical constants of SnTe nanofilm is of great significance for the design of high performance optoelectronic devices and their potential applications in the field of optoelectronics. However, there are still few reports about the methods to obtain the optical constants of the nanofilm. SnTe nanofilm was prepared on quartz substrate by magnetron sputtering with SnTe single target. Under the conditions of without heating the substrate and annealing treatment, using the appropriate process parameters, the crystalline and compositive controlled face-centered cubic SnTe nanofilm has been obtained. The thickness, composition, refractive index, extinction coefficient and other optical constants of SnTe nanofilm were studied by using spectral ellipsometry (SE). Different fitting model structures were established. SnTe material data lists in SE database and Tauc-Laurents model were used for fitting analysis respectively. The results show that the SnTe nanofilm with such thickness has a higher refractive index in the visible band and a wider spectral absorption from visible to near infrared.

  • 1
• Large zoom ratio infrared zoom imaging system based on linear motion mechanism

  ZHOU Pan-Wei, YU Yang, LI Fan-Ming, YE Xi-Sheng

  Abstract: (24) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  In order to meet the urgent need of large-scale search and accurate target recognition, a large zoom ratio infrared zoom imaging system is developed. Two independently moving zoom lenses and one compensating lens are designed, the large zoom ratio can be obtained by cascade of two zoom lenses. According to the characteristics of multiple moving lenses and complex zoom curve, the zoom motion is realized by linear motion mechanism, and driven by linear motor integrated encoder and thread screw rod. The mechanical analysis of system is carried out by finite element simulation, and the maximum displacement of the lenses is 3.04×10-^{3 mm.} The imaging system is suitable for the medium-wave infrared cooled 640×512 focal plane area-array detector, and the zoom ratio is 55. The results of laboratory imaging and outfield imaging show that the system has clear and good imaging quality in the process of continuous zoom from 6 mm focal length to 330 mm focal length, which verifies the performance of the system. The design is reasonable and reliable. The research findings of this paper have broad application prospects in search, tracking, reconnaissance and surveillance.

  • 1
• Progress in the study of nonlinear dynamic characteristics based on quantum cascade lasers

  f, m, m, r, w, Cao Jun-Cheng

  Abstract: (29) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Quantum Cascade Laser (QCL) is a unipolar semiconductor laser that relies on the excitation of photons radiated by electrons leaping between subbands of quantum wells. Numerous theoretical and experimental studies have demonstrated that slight external perturbations (optical feedback, optical injection) or sufficiently strong internal nonlinear mode coupling can induce nonlinear output of semiconductor lasers. QCL, as a new type of semiconductor device, is characterized by high intracavity strength, strong inter-subband optical nonlinearity and fast electron relaxation time, which has stimulated the interest in studying its nonlinear dynamics. In this paper, we review in detail the progress of the study of nonlinear dynamical characterization in QCL, explore the mechanism of the generation of nonlinear dynamical properties of QCL, and summarize the applications of nonlinear properties of QCL.

  • 1
• Research on Emissivity Directionality of Radiometric Calibration Sites for Optical Sensors

  LIU Jia-Xin, YANG Zhi-Wei, GAO Cai-Xia, MA Hui-Ya, ZHAO En-Yu, DUAN Si-Bo

  Abstract: (28) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The research on the surface emissivity directionality is a hot and difficult issue in the international thermal infrared quantitative remote sensing area. The existing emissivity directional models of sandy area in thermal infrared bands have some disadvantages, such as too many prior parameters, low accuracy and poor applicability. Therefore, with the aid of long-time series (2018-2020) multi-angle observation data from geostationary-orbit MSG/SEVIRI and polar-orbit AQUA/MODIS, after data pre-processing related to inter-sensor calibration, atmospheric correction, spatial and temporal matching, we retrieved the directional emissivity under different viewing zenith angles (VZAs) between 0~65°over five pseudo-invariant calibration sites based on the thermal infrared radiation transfer equation, including Algeria3_1km, Algeria5_1km, Libya1_1km, Mauritania1_1km and Mauritania2_1km. Subsequently, a model for retrieving the kilometer-scale directional emissivity was established, and its uncertainty was evaluated. The result shows that the surface emissivity decreases with the increase of VZA, and the directional effect decreases with the increase of the MODIS band central wavelength; Algeria5_1km has the smallest directional effect, and Mauritania1_1km has the strongest effect, the uncertainty of the directional emissivity model in each region increases with VZA, and is better than 3%.

  • 1
• Effect of Be doping in active region on the performance of 1.3μm InAs quantum dot lasers

  DU An-Tian, CAO Chun-Fang, HAN Shi-Xian, WANG Hai-Long, GONG Qian

  Abstract: (46) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  InAs DWELL quantum dot lasers were grown on GaAs(100) substrate by molecular beam epitaxy technology, and the effect of Be doping in active region on the performance of InAs quantum dot lasers has been studied. The results show that Be-doped in the active region could effectively reduce the threshold current density, improve the output power, and increase the temperature stability of the InAs quantum dot laser. The threshold current of Be-doped InAs quantum dot laser was reduced to 12mA, and the corresponding threshold current density was 100A/cm2. The highest output power of the laser was 183mW, and the highest operating temperature reaches 130℃. This is of great significance for the application of InAs quantum dot laser device in optical communication system.

  • 1
• Study of Zinc-diffused InGaAs/InP planar infrared detector processed with rapid thermal annealing

  CaoJiasheng, Li Tao, Yu Yi-Zhen, Yu Chun-Lei, Yang Bo, Ma Ying-Jie, Shao Xiu-Mei, Li Xue, Gong Hai-Mei

  Abstract: (31) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  The function of rapid thermal annealing on zinc-diffused In0.53Ga0.47As/InP PIN detector was systemically studied. By using electrochemical capacitance-voltage and secondary ion mass spectroscopy techniques, Zn and net acceptor concentration profiles were investigated, indicating that the annealing process would affect the dopant concentration but not affect the diffusion depth. In0.53Ga0.47As/InP PIN detectors under different annealing conditions were fabricated, the results showed that the detector without annealing process outperformed in terms of lower device capacitance and higher activation energy from 260 to 300K. By analyzing the mechanism of dark current, the unannealed sample exhibited lower Shockley-Read-Hall generation-recombination and diffusion currents, explaining the higher peak detectivity at room temperature. Therefore, for the purpose of fabricating high-performance planar InGaAs detectors with low-doped absorption layer, annealing process is inadvisable.

  • 1
• ACE-STDN: An infrared small target detection network with adaptive contrast enhancement

  YE Xin-Yi, GAO Si-Li, Li Fan-Ming

  Abstract: (45) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Due to the long distance and complex background, it is hard for the infrared detecting and tracking system to find and locate the dim-small targets in time. The proposed method, ACE-STDN, aims to tackle this difficult task and improve the detection accuracy. First of all, an adaptive contrast enhancement subnetwork preprocesses the input infrared image, which is conducive for the low-contrast dim targets. Next, a detection subnetwork with a hybrid backbone takes advantage of both convolution and self-attention mechanisms. Besides, the regression loss is designed based on 2D Gaussian distribution representation instead of Intersection over Union measurement. To verify the effectiveness and efficiency of our method, we conduct extensive experiments on two public infrared small target datasets. The experimental results show that the model trained by our method has a significant improvement in detection accuracy compared with other traditional and data-based algorithms, with the average precision reaching 93.76%. In addition, ACE-STDN achieves outstanding detection performance in a multiclass object dataset and a general small object dataset, verifying the effectiveness and robustness.

  • 1
• Depth estimation of thermal infrared images based on self-supervised learning

  Ding Meng, GUAN Song, LI Shuai, YU Kuai-Kuai, XU Yi-Ming

  Abstract: (50) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract:

  Depth estimation based on unsupervised learning is one of the important issues in the field of computer vision. However, existing algorithms of depth estimation are mainly designed based on visible images. Compared with visible images, thermal infrared images have the disadvantages of low contrast and insufficient detail information. To this end, this paper constructs a depth estimation network and proposes an unsupervised depth estimation method for thermal infrared images according to their characteristics. The network consists of three parts: feature extraction module, feature aggregation module, and feature fusion module. Firstly, a feature aggregation module is designed to improve the network"s ability to acquire the edge information of target objects and small object information of the image. Secondly, the channel attention mechanism is introduced in the feature fusion module to effectively capture the interaction relationship between different channels. Finally, a depth estimation network for thermal infrared images is established. In this network, the model parameters are trained by thermal infrared sequence images to achieve pixel-level depth estimation of a single thermal infrared image. The results of ablation studies and comparative experiments fully demonstrate the performance of the proposed method in pixel-level depth estimation of the thermal infrared image outperforms the other representative methods.

  • 1

Volume 42,2023 Issue 2

• 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: (1462) HTML (139) PDF (262.82 KKB)(49455)

  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 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: (7607) HTML (465) PDF (411.06 KKB)(19982)

  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 Spectral Analysis

• 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: (10424) HTML (415) PDF (221.64 KKB)(13698)

  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: (7200) HTML (402) PDF (271.63 KKB)(13177)

  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.

Image Processing and Software Simulation

• IMAGE SEGMENTATION BY SPECTRAL CLUSTERING ALGORITHM WITH SPATIAL COHERENCE CONSTRAINTS

  JIA Jian-Hua, JIAO Li-Cheng

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

  Abstract: (11118) HTML (387) PDF (808.83 KKB)(10714)

  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.

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

  ZHOU Yue, MAO Xiao-Nan

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

  Abstract: (11149) HTML (439) PDF (750.21 KKB)(10062)

  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.

• HYPERSPECTRAL REMOTE SENSING IMAGE CLASSIFICATION BASED ON SUPPORT VECTOR MACHINE

  TAN Kun, DU Pei-Jun

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

  Abstract: (2835) HTML (936) PDF (735.00 KKB)(10031)

  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.

• 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: (11615) HTML (435) PDF (1.12 MKB)(9618)

  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.

• 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: (1267) HTML (99) PDF (380.01 KKB)(9213)

  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.

• 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: (7696) HTML (181) PDF (466.11 KKB)(8289)

  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.

Terahertz and Millimeter Wave 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: (2425) HTML (131) PDF (1.09 MKB)(8023)

  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.

• Passive millimeter wave focal plane array imaging technology

  WANG Nan-Nan, QIU Jing-Hui, ZHANG Peng-Yu, DENG Wei-Bo

  2011,30(5):419-424, DOI:

  Abstract: (3468) HTML (195) PDF (1.64 MKB)(7882)

  Abstract:

  Under the background of safety inspection, the key technologies of near-range passive millimeter wave focal plane array imaging are studied. The analysis of the system quasi-optics were carried out using fundamental Gaussian beam method combined with geometrical optics method. A multi-beam wide-angle scanning lens antenna was designed. A new dielectric rod antenna was devised, which is prone to be aligned in close arrays and provide good radiation to the lens. Miniaturized direct-detection radiometers were fabricated with high-sensitive in Ka-band . Experimental results of the 20-channel passive millimeter wave focal plane array imaging system are presented, which can be used to detect hidden objects on human bodies in near range indoors.

Image Processing and Software Simulation

• HYPERSPECTRAL ANOMALY DETECTION ALGORITHM BASED ON BACKGROUND RESIDUAL ERROR DATA

  LI Jie, ZHAO Chun-Hui, MEI Feng

  2010,29(2):150-151, DOI:

  Abstract: (2441) HTML (62) PDF (571.44 KKB)(7748)

  Abstract:

  In order to overcome the serious background interferences for small target detection of hyperspectral imagery, a nonlinear anomaly detection algorithm based on the background residual error data was proposed. After the background endmembers were extracted, spectral unmixing technique was applied to all mixed spectral pixels to separate target information from complicated background clutter.Then, the unmixing residual error data that included abundant target information was mapped into a high-dimensional feature space by a nonlinear mapping function. Nonlinear information between the spectral bands of hyperspectral imagery was exploited and the anomaly targets could be detected by using RX operator in the feature space. Thus, the ninlinear statistical characteristics between the hyperspectral bands were used effectively on the basis of suppressing the large probability background information. Numerical experiments were conducted on real AVIRIS data to validate the effectiveness of the proposed algorithm. The detection results were compared with those detected by the classical RX algorithm and KRS which did not suppress the backguound information. The results show that the proposed algorithm has better detection performance, lower false alarm probability and lower computational complexity than other detection algorithms.

Infrared Materials and Devices

• Temperature dependent characteristics of HgCdTe variable-area photovoltaic detectors on Si substrates

  ZHANG Shan, HU Xiao-Ning

  2011,30(5):412-414, DOI:

  Abstract: (5073) HTML (160) PDF (704.75 KKB)(7555)

  Abstract:

  The variable-area HgCdTe/Si photovoltaic detector was investigated in this paper. By analyzing the relationship of dark current density (J) and the ratio of perimeter to area (p/A) under different reverse bias, it is indicated that the n-on-p type HgCdTe/Si photovoltaic detector has a significant surface leakage current under larger reverse bias. The minority carrier diffusion length at different temperature can be obtained by fitting the relationship between the product of zero-bias resistance and area (R0A) and p/A. It shows that the minority carrier diffusion length increases with the increase of temperature below 200 K, while the minority carrier diffusion length decreases with the increase of temperature above 200 K. The minority carrier lifetime of Hg-vacancy p-type HgCdTe on Si substrate was calculated from the minority diffusion length at different temperature. It was concluded that the lifetime of HgCdTe/Si minority carrier and its relationship with the temperature is the same as that of HgCdTe/CdZnTe material by comparing the minority carrier lifetime for these two kinds of materials.

• ANISOTROPIC GAUSSIAN FILTERING FOR INFRARED IMAGE

  WANG Huai-Ye, ZHANG Ke, LI Yan-Jun

  2005,24(2):109-113, DOI:

  Abstract: (1767) HTML (111) PDF (363.60 KKB)(7407)

  Abstract:

  为了在抑制噪声时尽可能保留图像边缘信息，提出一种自适应各向异性高斯滤波器设计方法．该方法由独立强度传播(IDS)模型决定滤波器的长轴尺度，由像素的邻域平滑度决定长短轴的比例，然后根据该处的灰度梯度方向自适应决定各向异性滤波器的长轴方向．仿真实验表明，提出的自适应各向异性滤波器具有很强的噪声抑制和边缘保持能力．

• INFLUENCE OF DEPOSITION POWER ON THE COMPOSITION, STRUCTURE AND PROPERTIES OF PZT THIN FILMS PREPARED BY RF SPUTTERING

  LI Xin-Xi 1, LAI Zhen-Quan 1, WANG Gen-Shui 2, SUN Jing-Lan 2 ZHAO Qiang 2, CHU Jun-Hao 2

  2004,23(4):313-316, DOI:

  Abstract: (1458) HTML (109) PDF (520.22 KKB)(7406)

  Abstract:

  用射频(RF)溅射法在镀LaNiO3(LNO)底电极的Si片上沉积PbZr0.52 Ti0.48 O3(PZT)铁电薄膜，沉积过程中基底温度为370℃，然后在大气环境中对沉积的PZT薄膜样品进行快速热退火处理(650℃，5min)．用电感耦合等离子体发射光谱(ICP-AES)测量其组分，X射线衍射(XRD)分析PZT薄膜的结晶结构和取向，扫描电子显微镜(SEM)分析薄膜的表面形貌和微结果，RT66A标准铁电综合测试系统分析Pt／PZT／LNO电容器的铁电与介电特性，结果表明，PZT薄膜的组分、结构和性能都与溅射沉积功率有关．

Terahertz and Millimeter Wave Technology

• Development and application of the millimeter wave SAR

  WANG Hui, ZHAO Feng-Jun, DENG Yun-Kai

  2015,34(4):452-459, DOI: 10.11972/j.issn.1001-9014.2015.04.013

  Abstract: (3168) HTML (165) PDF (3.92 MKB)(7366)

  Abstract:

  Synthetic aperture radar (SAR) is a microwave remote sensing radar with capability of all-day and all-weather imaging. Millimeter-wave SAR has become important for development of SAR with the advantage of small volume, light weight, and high resolution. The basic principle for high resolution imaging of millimeter-wave SAR is analyzed, and the advantage of millimeter-wave SAR is present. The state-of-art in the development of millimeter-wave SAR technologies and systems are illustrated with some typical millimeter-wave SAR systems. The application prospects, some issues, and future development trend of millimeter-wave SAR are also discussed.

Image Processing and Software Simulation

• INFRARED IMAGING MODEL FOR SCENE SIMULATION AND ITS VALIDATION

  LI Hong-Ning, BAI Ting-Zhu, CAO Feng-Mei, MA Shuai, XU Kai-Da, YANG Wei-Ping, FENG Jie

  2010,29(1):57-62, DOI:

  Abstract: (2844) HTML (136) PDF (472.80 KKB)(7293)

  Abstract:

  Based on the illumination model which is widely used in computer graphics and the radiance transfer law, a simplified thermal infrared imaging model is derived by: 1) adding the surface temperature distribution and the material parameters to the geometric model, 2) introducing the self emission and the detector property into the Illumination model. Using this model, the ray tracing method is applied to construct an infrared imaging system which can get the synthetic infrared images from any angle of view of the 3D scenes. Three typical 3D scenes are made to validate the infrared imaging model, and the infrared images are calculated to compare and contrast with the real infrared images obtained by a middle infrared band imaging camera. It shows that the thermal infrared imaging model is capable of producing infrared images which are very similar to those received by thermal infrared camera. Quantitative analysis shows that the absolute brightness does not match well, and the reasons are analyzed.

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: (3192) HTML (239) PDF (5.05 MKB)(7247)

  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%.

• STUDY ON HIGH RESOLUTION TIME INTERVAL MEASUREMENT MODULE IN PULSED LASER RANGING SYSTEM

  WU Gang, LI Chun-Lai, LIU Yin-Nian, DAI Ning, WANG Jian-Yu

  2007,26(3):213-216221, DOI:

  Abstract: (2111) HTML (213) PDF (268.18 KKB)(7223)

  Abstract:

  The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement. Therefore, a high resolution time interval measurement module was developed. The module is based on the special time-to-digital conversion chip which adopts the delay line interpolation method. The maximum measuring time of the module is 200ms, and the maximum time resolution is 125ps, of which the corresponding distance resolution is 18.75mm. The module is especially suit for the large distance measurement. The hardware and the software of the module as well as the testing results are also presented.