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MA Xiao-Le, GUO Jie, HAO Rui-Ting, WEI Guo-Shuai, WANG Guo-Wei, XU Ying-Qiang, NIU Zhi-Chuan
2021,40(5):569-575, DOI: 10.11972/j.issn.1001-9014.2021.05.001
Abstract:
Using GaSb bulk and InAs/GaSb superlattice as short wave and medium wave infrared absorbing materials respectively， a short/mid dual-band infrared detectors with NIPPIN structure were epitaxial growth and fabricated. HRXRD and AFM tests show the FWHM of zero order peak of InAs/GaSb superlattice and GaSb peak are 17.57 arcsec and 19.15 arcsec， respectively. Surface root mean square roughness RMS is 1.82
under . At 77 K， the maximum product RA of resistance and area of SiO2 passivated device is ， the dark current density is ， and side wall resistivity is . After anodic sulfuration， the maximum RA of the device is ， the dark current density is ， and side wall resistivity is . Sulfurization reduces dark current of the device by more than one order of magnitude and increases side wall resistivity by one order of magnitude under the same bias. The spectral response of the sulfurization device was tested， the device has the bais polarity-dependent dual-band detection performance with low crosstalk. The 50% cutoff wavelengths of the short-wave and medium-wave channels are 1.55 and 4.62 ， respectively. At 1.44 μm， 2.7 μm and 4 μm，the responsivity are 0.415 A/W， 0.435 A/W and 0.337 A/W， respectively. -
SHEN Chuan, YANG Liao, GUO Hui-Jun, YANG Dan, CHEN Lu, HE Li
2021,40(5):576-581, DOI: 10.11972/j.issn.1001-9014.2021.05.002
Abstract:
In this paper， 2-D numerical simulation was used to simulate the structure of MWIR HgCdTe APD， and the structural parameters of APD devices at 80K were obtained by comparing with the experimental results. At the same time， the influence of dark current mechanism on APD devices at different operating temperatures was studied. The performance of APD devices with the change of each parameter under the condition of high operating temperature was studied. We proposed the optimal HgCdTe APD structure for achieving high performance at 150K. The structure provides an important reference for the subsequent development of APD devices with high operating temperature.
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KE Peng-Yu, LIU Meng-Xuan, WANG Xu-Quan, HUANG Song-Lei, ZHANG Yong-Gang, FANG Jia-Xiong
2021,40(5):582-588, DOI: 10.11972/j.issn.1001-9014.2021.05.003
Abstract:
Based on a 512 × 2-element InGaAs spectrum module， a new spectral-sensing IoT node is developed. The detector uses two parallel column structure with 25 μm pixel pitch. In order to reduce the impact on an abnormal response to a single pixel， the data onto two channels is averaged in the circuit. The experimental results show that the test wavelength range of this node is 976~1700 nm， and the spectral resolution is 13.5 nm. The wavelength accuracy is better than 3.2 nm， and the wavelength repeatability is better than 0.3 nm. The dynamic range is 2300：1， and the absorbance repeatability is 0.0011 AU. The baseline stability of light source is better than 0.0001 A/h. The function of the sensor node was verified by using alcoholic beverages samples of different nominal concentrations.
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GUO Jia-wei, TAN Wei, XIE Jian-lan, LIU Jian-jun
2021,40(5):589-594, DOI: 10.11972/j.issn.1001-9014.2021.05.004
Abstract:
One-dimensional photonic quasi-crystal （1D PQC） has continuously shown their superiority in the fields of sub-wavelength focusing， sub-diffraction focusing and super-resolution imaging. In order to enrich and expand the application of its focusing characteristics， a 1D PQC plano-V lens is proposed and the effect of material thickness on its focusing characteristics is studied in this paper. The results show that the lens can achieve sub-wavelength focusing and sub-diffraction focusing in a wide wavelength range of the second band. The results in this paper will provide reference for the design and application of 1D PQC plano-V lens.
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WEI Guo-Shuai, HAO Rui-Ting, GUO Jie, MA Xiao-Le, LI Xiao-Ming, LI Yong, CHANG Fa-Ran, ZHUANG Yu, WANG Guo-Wei, XU Ying-Qiang, NIU Zhi-Chuan, WANG Yao
2021,40(5):595-604, DOI: 10.11972/j.issn.1001-9014.2021.05.005
Abstract:
In this paper， high quality InAs/InAsSb（Ga-free） type-II superlattice were grown on GaSb substrates by molecular beam epitaxy. The superlattice layers structure consists of 100 periods with 3.8 nm thick InAs layers and 1.4 nm InAs0.66Sb0.34 layers. A specific spike-like defect was found during experiment. The epitaxial layer was characterized and analyzed by high-resolution x-ray diffraction （HRXRD）， atomic force microscope （AFM） and Fourier transform infrared spectroscopy （FTIR）. The results show that the optimized sample is almost zero lattice mismatched， the FWHM of the zeroth order SL peak is 39.3 arcsec， the RMS surface roughness achieves around 1.72? over an area of 10 μm×10 μm. The FTIR absorption spectrum shows a 50% cutoff wavelength of 4.28 μm. And PL spectrum shows that the peak of InAs/InAs0.66Sb0.34 SL is at 4.58 μm. These initial results indicate that the grown InAs/InAsSb SL is stable and reproducible， and thus it is worthy of further investigation.
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WU Qiong, YANG Mei-Lin, YIN Hong-Gang, SHANG Jian
2021,40(5):605-615, DOI: 10.11972/j.issn.1001-9014.2021.05.006
Abstract:
In order to meet the urgent requirement for China spaceborne cloud radar detection and accurate retrieval of cloud microphysical properties， integrating the detecting advantages of dual-frequency 94/220 GHz cloud radars， and combining scattering and attenuation properties of non-spherical ice particles， a dual-frequency retrieval algorithm of cloud microphysical parameters is proposed based on the non-spherical ice particles scattering database. By assuming the gamma particle size distribution of cloud ice and establishing relationships between dual frequency ratio and retrieval variable volume median diameter， three types have been chosen. Based on it， the optimal solutions of particle size distribution parameters are obtained after backward iteratively calculating， then the microphysical parameters of cloud could be retrieved based on particle size distribution， and the error can be calculated and analyzed. By adding system noise and random noise， the retrieval errors are compared with original data and the requirement of signal-to-noise ratio is proposed. As a result， the retrieval of non-spherical ice cloud microphysical parameters based on dual-frequency 94/220GHz and iterative backward retrieval algorithm is well consistent with simulated true data. What’s more， the signal-to-noise ratio cannot be smaller than 11.39dB in order to get 30% retrieval error for ice water content under 0.2g/m3， which gives some references for domestic spaceborne cloud radar design and retrieval research of non-spherical ice cloud microphysical parameters.
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HUI Zhan-Qiang, ZHANG Tian-Tian, HAN Dong-Dong, ZHAO Feng, ZHANG Mei-Zhi, GONG Jia-Min
2021,40(5):616-626, DOI: 10.11972/j.issn.1001-9014.2021.05.007
Abstract:
A novel broadband high birefringence terahertz photonic crystal fiber （PCF） with cascaded hexagonal unit porous core based on Topas cycloolefin copolymer is proposed. The full vector finite difference method is used to analyze the guided wave characteristics. The results show that the ultra-high birefringence of 0.096 5 （close to 10-1）， the ultra-low confining loss of 10-12 dB/cm and the effective material absorption loss less than 1 cm-1 are obtained at the frequency of 3.5 THz. In addition， the proposed PCF exhibits nearly zero flat dispersion of ± 0.2 ps/THz/cm in the frequency of 2.25~5 THz. The birefringence value of the proposed PCF is not only the highest among the reported THz polymer fibers， but also the novel porous core structure effectively reduces the transmission loss of THz wave. Moreover， only circular air holes are used in the fiber， which is feasible for engineering fabrication. This work has certain reference value for the future development of THz PCF.
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Analysis of oscillation-starting characteristics in millimeter wave extended interaction oscillators
XU Che, MENG Lin, YIN Yong, BI Liang-Jie, CHANG Zhi-Wei, LI Hai-Long, WANG Bin
2021,40(5):627-633, DOI: 10.11972/j.issn.1001-9014.2021.05.008
Abstract:
The investigations of the oscillation-starting characteristics of a ladder-type RF circuit are proposed to overcome the limitation of high ohmic loss for development of millimeter-wave extended interaction oscillators （EIOs）. Based on PIC-simulations， quantitative calculations and theoretical analyses， the designed and fabricated W-band EIO is proved to have the possibility of greatly reducing the oscillation-starting current. By optimizing five aspects including the gap number， cavity dimension， field distribution， operation voltage， and surface loss， the oscillation-starting current of the EIO can be reduced to 0.43 A with a beam voltage of 17.5 kV. According to cold test experiment， the output power attenuation is analyzed and predicted.
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NIU Bin, QIAN Jun, FAN Dao-Yu, WANG Yuan-Qing, MEI Liang, DAI Jun-Jie, LIN Gang, ZHOU Ming, CHEN Tang-Sheng
2021,40(5):634-637, DOI: 10.11972/j.issn.1001-9014.2021.05.009
Abstract:
664 GHz sub harmonic mixer for ice cloud detection was designed and fabricated， based on 0.5 μm “T” anode GaAs SBD membrane integrated process with thickness of 5 μm. Parasitic parameters of “T” anode design were analyzed and membrane process was developed to improve high frequency performance. The mixer was characterized in 664 GHz receiver setup. Double side band conversion loss of the mixer was 9.9 dB at 664 GHz room temperature.
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YU Yang, YOU Yan, CHEN Xu-Dong, QIAO Ling-Bo, ZHAO Zi-Ran
2021,40(5):638-646, DOI: 10.11972/j.issn.1001-9014.2021.05.010
Abstract:
Millimeter-wave （MMW） imaging is of interest as it has played an essential role in personal surveillance. The existing MMW short-range imaging mechanisms in personal surveillance can be mainly divided into SISO and MIMO. The SISO mechanism can achieve fast and accurate imaging. However， as the operating frequency increases， the number of antennas required increases rapidly， and the antenna spacing decreases， which not only causes an increase in system cost， but also makes it difficult to suppress antenna coupling. Although the MIMO mechanism reduces the number of antennas required for imaging and increases the antenna spacing， it is currently unable to achieve rapid and accurate reconstruction comparable to the SISO mechanism. In this paper， a MIMO short-range imaging mechanism has been proposed， which is well-suitable for fast and accurate reconstruction， and the applicable conditions of the mechanism were given quantitatively. Unlike the traditional MIMO short-range imaging mechanism， the proposed MIMO imaging mechanism satisfies the principle of equivalent phase center （EPC） in short-range imaging by ingeniously designing MIMO sub-arrays. Therefore， it can directly use various accurate and fast imaging algorithms developed for SISO mechanism to reconstruct images， such as range migration algorithm （RMA）. It means that the algorithm has the advantages of both SISO mechanism and MIMO mechanism. The demonstrations in E-band show that the proposed MIMO mechanism exhibits the same level of imaging quality and reconstruction speed as SISO mechanism in short-range imaging， but the antenna utilization rate and the antenna spacing can be increased by more than 4 times. When compared with the traditional MIMO imaging mechanism， the proposed MIMO mechanism not only has better imaging quality but also greatly improves the reconstruction speed， which is nearly 200，000 times faster than the traditional MIMO mechanism in a typical imaging scene of 1m×1m×0.2m volume with a voxel size of 1.85 mm3 . Both simulation and experimental results verify the effectiveness of the proposed MIMO mechanism.
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WU Zi-Xian, GUO Cheng, WEN Xiao-Zhu, SONG Xu-Bo, LIANG Shi-Xiong, GU Guo-Dong, ZHANG Li-Sen, LYU Yuan-Jie, ZHANG An-Xue, FENG Zhi-Hong
2021,40(5):647-654, DOI: 10.11972/j.issn.1001-9014.2021.05.011
Abstract:
This paper presents a design method of high-power triple frequency multiplier based on on-chip integrated capacitor technology and band-stop filter structure. The DC bias circuits of the tripler was improved by using the on-chip integrated capacitor based on beam lead structure so that the DC feed and RF ground were achieved simultaneously. Also， a more compact structure of the tripler was built and the model accuracy was improved. Then， the bandstop filter was used to replace the traditional stepped impedance lowpass filter to suppress the third harmonic. Hence， the structure of the tripler is further simplified while the performance is improved. A 110 GHz tripler and a 220 GHz tripler were fabricated and measured， respectively. The results show that when the input power is 500 mW， the maximum output power of 110 GHz tripler reaches 140 mW with 30 % peak efficiency. When the input power is 300 mW， the peak efficiency of 220 GHz tripler reaches 15 % and the maximum output power is 45 mW. Performance of two triplers validates the design method.
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SHENG Yi-Cheng, DUN Xiong, QIU Su, LI Li, JIN Wei-Qi, WANG Xia
2021,40(5):655-663, DOI: 10.11972/j.issn.1001-9014.2021.05.012
Abstract:
Numerous detectors and the large time scale make non-uniformity correction （NUC） challenging for an infrared focal plane array. Typical calibration systems for infrared remote sensing systems block the full optical pupil and expose the sensor to an on-board calibration source （blackbody） and may also point to deep space as a calibration source. It is impractical （or expensive） to calibrate the high dynamic range remote sensing system with an on-orbit full aperture calibration source. This paper proposes and simulates an internal calibration system wherein a controllable internal calibration illumination is superimposed on the space imagery. The CICS-NUC method is applicable to the NUC when the calibration source adopts steady-state mode. After a comprehensive simulation analysis， an on-orbit NUC method based on the controllable internal calibration sources （CICS-NUC） is proposed using this type of calibrator. The proposed approach provides effective NUC without blocking the full optical pupil when the sensor stares at deep space. After executing the proposed NUC method， the non-uniformity of the evaluation image was reduced from an initial pre-correction value of 15.87% to a post-NUC value of 1.2%. The proposed approach has advantages of high efficiency， adaptability， and real-time processing. In addition， compared with the scheme of cutting a large extended blackbody into the imaging optical path， the simple structure and compact design of the internal calibration device reduce system costs.
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2021,40(5):664-672, DOI: 10.11972/j.issn.1001-9014.2021.05.013
Abstract:
Synthetic Aperture Radar （SAR） imaging under sparse constraint can effectively obtain useful information of the target''s distinctive points by enhancing the sparse features with the sparse prior representation. However， this process cannot recover the structure feature of the target， and it is very sensitive to inevitable non-systematic errors. To this end， this paper proposes a sparse recovery high-resolution SAR imaging algorithm for Structure feature Enhancement based on Alternating Direction Method of Multipliers （ADMM） method （SE-ADMM）. The algorithm introduces Total Variation （TV） regular term to characterize structural features and play a role in enhancing the structure， introduces
norm to represent sparse features， which can suppress noise， and the entropy norm is introduced to characterize the focusing feature to ensure that the algorithm is insensitive to non-systematic errors. Under the framework of ADMM multi-feature optimization， the "Local-Global" operation mechanism is used to first derive the proximal operators of the three features respectively to obtain the corresponding feature analytical solutions， and then perform the target global optimization to ensure the coordination and balance between the feature solutions. In addition， the reference of multi-splitting variables and multi- regular under the ADMM multi-task framework ensures the efficiency and robustness of the algorithm. In the experimental part， the simulation data and measured data of SAR are selected successively to verify the effectiveness of the algorithm. The recovery performance of the proposed algorithm was quantitatively analyzed through phase transition analysis， and the robustness and advantages of SE-ADMM algorithm proposed in this paper are further verified. -
ZHONG Li, SU Xiao-Feng, HU Wei-Da, CHEN Fan-Sheng
2021,40(5):673-679, DOI: 10.11972/j.issn.1001-9014.2021.05.014
Abstract:
For the under-sampled imaging infrared search and tracking system which
<2， the energy of point target was concentrated on a single pixel. Due to the spatial non-uniformity of intra-pixel sensitivity （IPS） for focal plane array， the calculation accuracy of energy and centroid for point target would be reduced. Light spot scanning test and numerical simulation could effectively characterize and analyze the IPS， but the system and model were highly complex and time-consuming， moreover， experimental tests couldn’t analyze the relationship between the spatial non-uniformity of the IPS and the parameters of photo-detector. Aimed at the above problem， Monte Carlo methods were used to simulate the IPS of HgCdTe infrared focal plane array， and the influencing factors of its spatial non-uniformity were analyzed. The results showed that the spatial non-uniformity of IPS can be reduced by reducing the pixel pitch or increasing the thickness of absorber. With the increase in wavelength， the spatial non-uniformity of IPS increased slightly. The results of simulation and analysis are of great significance for improving the measurement accuracy of high energy concentration point target. -
TONG Hao-Chen, TANG Shu-Min, YE Shu-Ming, Duan Xiao-xiao, LI Xiao-Nan, XIE Ji-Yang, ZHANG Lu-Ran, YANG Jie, QIU Feng, WANG Rong-Fei, WEN Xiao-Ming, Yang Yu, CUI Hao-Yang, WANG Chong
2021,40(5):680-684, DOI: 10.11972/j.issn.1001-9014.2021.05.015
Abstract:
An effective enhancement of the photoluminescence from the Si+/Ni+ ions co-implanted silicon-on-insulator （SOI） by directly constructing the Au nanodisk-array photonic crystals is reported. The finite-difference time-domain method （FDTD） was employed to design and analyze the luminescence amplification of the metal film with a photonic crystal structure for luminesce from the optical defects in the SOI. The Langmuir-Blodgett （LB） method and inductively coupled plasma （ICP） etching were used to fabricate the etched Au-nanostructure photonic crystal directly on the top of SOI wafers. It indicates that the introduction of polystyrene （PS） spheres can effectively improve the luminescent efficiency in the near infrared waveband. This photonic crystal with simply fabricating processes and high efficiency exhibits great application on the optical quantum of Si-based photonics.
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LIU Shi-Jie, LI Chun-Lai, XU Rui, TANG Guo-Liang, WU Bing, XU Yan, WANG Jian-Yu
2021,40(5):685-695, DOI: 10.11972/j.issn.1001-9014.2021.03.020
Abstract:
Compressed sensing-based spectral imaging systems need to decode the sampled data by a proper algorithm to obtain the final spectral imaging data. Traditional decoding algorithms based on single sparse domain transformation will lead to loss of spectral details. Addressing this problem， a solution is proposed by using transformation of two sparse domains. A signal was decomposed into a low frequency part and a high frequency part， sparse restoration was performed according to the characteristics of different frequencies， and then decoding was performed to obtain high-precision restored signals. In data verification， the OMP algorithm was firstly used to restore the spectral information profile in the frequency domain， then the IRLS algorithm was applied to compensate the spectral details in the spatial domain. The impact of different sparse transformations on parameter settings was analyzed， and the JDSD of different algorithm combinations was tested. Test and simulation results on 500 kinds of spectral data show that the joint solution of double sparse domains can greatly improve the fidelity of spectral restoration. With a sampling rate of 20%， the SAM and GSAM indexes are increased from 0.625 and 0.515 by traditional methods to 0.817 and 0.659， respectively. In the case of 80%sampling rate， the SAM and GSAM indexes are increased from 0.863 and 0.808 of traditional methods to 0.940 and 0.897， respectively. JDSD algorithm can maintain high-precision details such as spectral absorption peaks，which is of great significance.
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ZHU Wen-Qing, TANG Xin-Yi, ZHANG Rui, CHEN Xiao, MIAO Zhuang
2021,40(5):696-708, DOI: 10.11972/j.issn.1001-9014.2021.05.017
Abstract:
Infrared and visible image features are quite different， and there are no ideal fused images supervise neural networks to learn the mapping relationship between the source images and the fused images. Thus， the application of deep learning is limited to the field of image fusion. To solve this problem， a generative adversarial network framework based on attention mechanism and edge loss is proposed， which is applied to the infrared and visible image fusion. Derived from the thoughts of attention mechanism and adversarial training， the fusion problem is regarded as an adversarial game between the source images and the fused images， and combining channel attention and spatial attention mechanism can learn nonlinear relationship between channel domain features and spatial domain features， which enhances the expression of salient target features. At the same time， an edge-based loss function is proposed， which converts the mapping relationship between the source image pixels and the fused image pixels into the mapping relationship between the edges. Experimental results on multiple datasets demonstrate that the proposed method can effectively fuse infrared target and visible texture information， sharpen image edges， and significantly improve image clarity and contrast.
Volume 40,2021 Issue 5
Infrared Materials and Devices
Terahertz and Millimeter Wave Technology
Remote Sensing Technology and Application
Infrared Photoelectric Technology and Application
Image Processing and Software Simulation
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YE Zhen-Hua, LI Hui-Hao, WANG Jin-Dong, CHEN Xing, SUN Chang-Hong, LIAO Qing-Jun, ZHOU Song-Min, LIN Jia-Mu, HUANG Ai-Bo, LI Hui, PAN Jian-Zhen, WANG Chen-Fei, CHEN Hong-Lei, CHEN Lu, WEI Yan-Feng, LIN Chun, HU Xiao-Ning, DING Rui-Jun, CHEN Jian-Xin, HE Li
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Infrared electro-optical detection technology usually works in the passive sensing mode and contains the advantages of long acting-distance， good anti-interference， excellent penetration of smoke and haze， and all-day operation， which has been widely used in space remote sensing， military equipment， astronomical detection and other aspects. So far， second-generation and third-generation infrared electro-optical detectors have been deployed widely. High-end third-generation infrared electro-optical detectors have been gradually promoted to practical application. Fourth generation and more forward-looking research including new concept， new technology， new device has been proposed. This paper focuses on the research status of infrared technology at home and abroad， emphatically introducing the hot spots and development trends of infrared electro-optical detectors. Firstly， the concept of SWaP3 is introduced due to tactical ubiquity and strategic high performance. Secondly， the high-end third-generation infrared electro-optical detectors with ultra-high spatial resolution， ultra-high energy resolution， ultra-high time resolution and ultra-high spectral resolution are reviewed. Technical characteristics and implementation methods of ultimate-performance infrared detectors are analyzed. Then， the fourth-generation infrared electro-optical detector based on the artificial micro-structure is discussed. The realization approaches and technical challenges of multi-dimensional information fusion such as polarization， spectrum and phase are mainly introduced. Lastly， highly innovative trends of future detectors are discussed according to upgradation from on-chip digitization to on-chip intelligence.
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CHANG Shao-Jie, WU ZHEN-Hua, HUANG Jie, ZHAO Tao, LIU DI-Wei, HU Min, WEI YAN-Yu, GONG YU-Bin, LIU Sheng-Gang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Terahertz wave has great potential in deep space exploration， nondestructive testing， communication and security inspection because of its electronics and photonics properties. The rapid development of terahertz technology in recent years is inseparable from the continuous progress of terahertz vacuum electronic devices. Due to the size sharing effect and the limitation of electron beam emission performance， this kind of devices have encountered no small difficulty in the process of moving to higher frequency band. To solve these problems， a series of measures have been taken， such as improving high-frequency structure， controlling machining accuracy， preparing materials with better performance and more accurate calculation methods. This paper introduces the solutions and latest progress of several mainstream miniaturized terahertz devices， and finally summarizes the problems and solutions that may be encountered in the future according to the current development situation.
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Zhao Peng, Jiang Zhen-Hua, Lu Zhi, Qu Xiao-Ping, Wu Yi-Nong
DOI:
Abstract:
Linear and coaxial PTCs are widely used in space, especially coaxial PTCs. The coaxial PTC has a compact structure and is more convenient to use, while the linear structure is simple with high cooling efficiency. At present, the research on the difference between the two PTCs base on theoretical research is relatively rare. Therefore, it is very valuable to carry out some comparative studies between the two PTCs. Two kinds of Stirling-type single-stage PTCs (in-line and coaxial type) are analyzed due to their different structures in this paper. One-dimensional numerical model is established to analyze the changes of the relevant thermodynamic parameters in the two cryocoolers. The mechanism is revealed that different structural changes could lead to different cooling performance. The differences of the PTCs are compared by analyzing the energy flows, acoustic impedance networks. Also, two experimental setups are established, and the performance of the two pulse tube cryocoolers are tested and analyzed. The results show that the in-line cryocooler has higher cooling efficiency, and the coaxial one could reach lower cooling temperature at the same input power because the pulse tube is placed in the regenerator of the coaxial system and precooled by the regenerator. By comparing the simulation data with the experimental results, it is found that there is a good consistency.
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Zhang Qiwen, Chen Honglei, Ding Ruijun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
HgCdTe avalanche photodiode （APD） is a frontier research on infrared focal plane technology， High-precision time stamp readout circuit is the basis of the APD focal plane at 77 K， which directly affects APD infrared focal plane performance. Time-to-digital conversion circuit （TDC） is one of the methods to achieve high-precision time stamping. Based on the analysis of MOSFET device at low temperature， we design a vernier TDC circuit， which uses a synchronous counter to quantize an integer multiple of the period to achieve a coarse count of 6 bits； We uses the high-frequency clock multiplied by the on-chip phase-locked loop to quantify the part that is less than one clock cycle to achieve a fine-count of 6 bits output. The circuit adopts standard CMOS process tape out， our circuit works at a master-frequency of 120 MHz. At 77 K， the circuit test can distinguish the time resolution of 236.280 ps. The DNL is within -0.54~0.71 LSB， and INL is within -1.32~1.21 LSB.
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CHEN Xu, YANG Qi, ZENG Yang, WANG Hong-Qiang, DENG Bin
DOI:
Abstract:
In this article， an improved millimeter-wave fast imaging algorithm with range compensation for one-stationary bistatic synthetic aperture radar （OS-BiSAR） is presented. During the process of image reconstruction， the amplitude attenuation factor in the echo model is retained for the compensation of signal propagation loss， and the convolution operation is performed on the receiving array dimension according to the characteristics of the target echo equation. Finally， the target image can be solved by fast Fourier transform （FFT） and coherent accumulation steps. Simulation analysis and experimental results show that， compared to the range migration algorithm （RMA） with range compensation， the proposed algorithm can not only guarantee the efficiency of image reconstruction， but also significantly reduce the influence of signal propagation loss on the image quality.
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ZHANG Shuai-Jun, LI Tian-Xin, WANG Wen-Jing, LI Ju-Zhu, SHAO Xiu-Mei, LI Xue, ZHENG Shi-You, PANG Yue-Peng, XIA Hui
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Scanning Capacitance Microscopy （SCM） was applied to obtain the 2-dimensional carrier distribution on the cross-section of planar type InGaAs/InAlAs pixels. The profile of pn junction in the device structure was able to be depicted with high space resolution. Besides， for InGaAs/InP detector， the SCM study helps to disclose the distinct diffusion behavior of p-type impurities in different functional layers. The lateral diffusion speed of zinc in InGaAs absorption layer was decided as 3.3 times than that in the depth direction， which is significantly higher than the lateral to depth ratio of 0.67 in the n-InP cap layer， this could affect the both the capacitance and dark current properties of the diode pixels.
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ZHANG Da-Wei, Xu Xin, Li Bin, Xu Hui, Yu Hong-Xi, Li Jun, Ma Kai-Xue, Bharatha Kumar Thangarasu, Kiat Seng Yeo
DOI:
Abstract:
This paper presents the work of a miniaturized 60-GHz balun chip with isolation and matching performance fabricated in 0.18-μm SiGe BiCMOS process. The use of isolation circuit as key building blocks within a 60-GHz transformer balun leads to an improved isolation performance between output ports， while simultaneously achieving the matching performance of them. Moreover， compared to the conventional isolation circuit， artificial left-handed transmission line is introduced to remove the bulky distributed elements， and capacitive loading compensation technique is utilized for both matching and miniaturization. Both electromagnetic simulation and measurement results of the proposed 60-GHz transformer balun chip design with isolation and matching characteristic are given with good agreement. From measurement results， better than 25-dB isolation and 18-dB return loss of the output ports have been achieved at 60 GHz， with an occupied area of 0.022 mm2.
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Zhao Lijuan, Zhao Haiying, Xu Zhiniu, Liang Ruoyu
DOI:
Abstract:
本文提出了一种可用于化学传感的具有高双折射、低损耗的光子晶体光纤，并系统地分析了空气孔参数对光纤光学特性的影响。研究表明，最优结构的光纤在典型波长1.55 μm时对水、乙醇和苯的相对灵敏度分别可达56.3%、59.9%和62.5%，相比现有光子晶体光纤分别提高1.05-6.25倍、1.05-4.99倍和1.03-4.63倍。此外，该光纤还具有较好的传输特性。因此，本文提出的光子晶体光纤在化学传感和生物医学领域方面更具优势。
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FAN Wen-long, HUANG Xiaoxian, FU Yu-tian
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The three elements of water color remote sensing products are chlorophyll， suspended substance and yellow substance. As one of the main loads of HY-1 satellite， Chinese Ocean Color and Temperature Scanner （COCTS） has set up 8 visible and near-infrared detection channels， to provide primary data for the study of global ocean primary productivity distribution. HY-1B COCTS was launched in 2007， and at the beginning of orbit entry there exists light pollution in cold space which works as the zero-radiation datum， which leads to the signal cut-off in the deep-sea area of the near-infrared detection channel， and the lower the latitude， the bigger the cold air signal is. In order to study the mechanism of the problem and repair the historical data of HY-1B COCTS， the characteristics of the source of the problem was verified in laboratory， and the influence mechanism was analyzed. Based on the relationship between the sun glint energy of HY-1C COCTS and the solar zenith angle， the sun glint energy of HY-1B COCTS at different solar zenith angle is calculated. According to the radiometric calibration coefficient， the corresponding code value of the sun glint energy and the correction quantity can be obtained. The results show that the correction quantity is linear with the energy calculated from the solar zenith angle， and can be used to repair other target signals of HY-1B COCTS. This algorithm can be used to repair the remote sensing data of nearly 9 years of HY-1B COCTS. It lays a theoretical foundation for data comparison with the same kind of ocean remote sensing instrument and retrieving water color products.
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Dong Yang, Guo Jing-Yu, Wang He-Xin, Wang Zhan-Liang, Lu Zhi-Gang, Gong Hua-Rong, Duan Zhao-Yun, Gong Yu-Bin, Wang Shao-Meng
DOI:
Abstract:
A dual-beam rectangular ring-bar (DBRRB) slow wave structure (SWS)， which is with a planar structure and is suitable for microfabrication， is proposed for W-band traveling-wave tubes (TWT). Supported by a pair of T-shaped dielectric rods， the RRB SWS is fit for dual-sheet beam operation. The high frequency characteristics are analyzed by using computer simulations. Wide bandwidth input-output structures adopting tapered structure and step waveguide are designed. Hot-test performance of the RRB SWS is investigated by means of Particle-in-cell (PIC) simulations. A solenoid magnetic field of 0.6 T is adopted to focus the sheet beams with voltage and current of 11.2 kV and 0.12 A. The saturated output power of 56.7 W at 94 GHz is obtained at the output port， corresponding a gain of 27.4 dB. In addition， an attenuator is added to suppress oscillations and achieve stable operation.
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MA Nan, DOU Cheng, WANG Man, ZHU Liang-Qing, CHEN Xi-Ren, LIU Feng, SHAO Jun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this work， excitation power-dependent infrared photoluminescence （PL） measurements were carried out on four GaSb0.93Bi0.07/GaSb single quantum well （SQW） samples with different in-well δ-doping density as well as the corresponding reference SQW samples without doping. PL integral-intensity evolutions of the GaSbBi SQW and the GaSb barrier/substrate show a significant decrease in the infrared emission efficiency caused by the in-well δ-doping. The doping-induced relative decrease rate is about
. Further analysis indicates that the reduction of the infrared emission efficiency is a co-consequence of the "electron loss" caused by the interfacial deterioration and the "photon loss" caused by the GaSbBi lattice quality deterioration. This work may be helpful in optimizing the performance of dilute Bi infrared light-emitting devices. -
XU Shou-Xi, YANG Jie, WANG Hu, GENG Zhi-Hui, ZHANG Rui
DOI:
Abstract:
A high efficiency Denisov-type quasi-optical mode converter for a 170GHz TE31，8 mode gyrotron is presented. The mode converter comprises a dimpled-wall launcher and a mirror system. Based on the coupled mode theory， the advanced launcher having two stages of perturbations is investigated. A mirror system of the converter is optimized and designed by using the vector diffraction theory. Simulation results show that the good Gaussian mode is converted from the circular waveguide TE31，8 mode and the mode conversion efficiency of a quasi-optical mode conveter is 93.7%.
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ZHANG Jin, TAN Bing-chong, TAO Xing-zhu, XU Cheng-cheng, CHANG Tian-ying, CUI Hong-liang, WANG Jie
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A spectral analysis algorithm based on the combination of Hilbert transform and power spectrum estimation has been proposed, and the terahertz reflection time domain waveform was processed. At the same time, the algorithm was applied to terahertz time domain spectroscopy imaging, defect thickness was correlated with image gray level, and the thickness, position and shape of defects in glass fiber laminate can be detected by imaging simultaneously. The experimental results show that when the multi-signal classification spectrum estimation and auto regressive spectrum estimation are combined with Hilbert transform, the reflected pulses between upper and lower surfaces of defect with thickness of 0.08 mm can be successfully distinguished, the time resolution of reflected pulses is higher than 0.5 ps, and the detection error of defect thickness is no more than 0.03 mm.
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YANG Jing, QIU Jiefu, JIANG Hui, HU Min, LIU Shenggang, ZHANG Hui
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Over the last several years， Terahertz spectroscopy has been used in different fields， including archaeology and cultural heritage conservation. This paper presents a review of the terahertz technology applied to paintings， focusing on THz-TDS （terahertz time domain spectroscopy） in pigment identification， terahertz imaging technology in fresco and oil painting study， some other new technologies are also discussed.
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TIAN Yan-Yan, WANG He-Xin, SHI Xian-Bao, LI XIN-Yi, GONG Yu-Bin, HE Wen-Long
DOI:
Abstract:
In this paper， a design， fabrication and cold test of a high efficiency folded groove waveguide （FGW） for w-band （85-110GHz） sheet beam traveling wave tube （TWT） is proposed. one stage phase velocity taper （OSPVT） was used in the FGW to enhance the electronic efficiency of a millimeter-wave sheet beam TWT. The OSPVT was realized via a change of the period of the FGW. Three FGWs with and without OSPVT were fabricated and their measured s-parameters demonstrate good transmission characteristics and wide bandwidth. Moreover， wave dispersions and phase velocities of the unchanged and OSPVT FGWs were obtained from measured transmission phases. 3-D particle-in-cell simulations of beam-wave interaction predicted that the proposed TWT with an OSPVT of twenty half periods could output a saturated power of 240 W at 95 GHz， which is about 70 W higher than the case of without OSPVT. Meanwhile， the application of the OSPVT improves the electronic efficiency in the whole operating frequency range of 85-110GHz， with a maximum efficiency enhancement of about 47% in the vicinity of 95GHz.
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LI Liu-Meng, ZHOU Bin, GAO Li-Chen, JIANG Kai, ZHU Liang-Qing, ZHANG Jin-Zhong, HU Zhi-Gao, CHU Jun-Hao
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
High quality β-Ga2O3-δ films on c-sapphire substrates are deposited by pulsed laser deposition （PLD） under various oxygen partial pressures. The crystalline structure， chemometry and optical properties of the β-Ga2O3-δ films are investigated systematically by X-ray diffraction （XRD）， far-infrared reflectance spectra， X-ray photoelectron spectroscopy （XPS） and ultraviolet-visible-near infrared （UV-vis-NIR） transmittance spectra. The XRD analysis shows that all the as-deposited films are of unique （-201） orientation. The transmittance spectra reveal that the films exhibit high transparency above 80% in the UV-vis-NIR wavelength region above 255 nm （4.863 eV）. Moreover， the optical constants and optical direct bandgap are extracted based on the transmittance spectra with Tauc-Lorentz （TL） dispersion function model and the Tauc’s relationship， respectively. A further step， the influence of oxygen partial pressure on optical properties is explained by theoretical calculation.
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LI Li-Yuan, LI Xiao-Yan, HU Zhuo-Yue, SU Xiao-Feng, CHEN Fan-Sheng
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Synthetic aperture radar (SAR) has the advantages of all-sky and all-weather earth observation without cloud interference. Ship detection based on SAR images has been widely used in civil and military fields, including maritime search and rescue, port reconnaissance, territorial sea defense. However, different from large ships, the misdetection rate of small ships with fewer pixels and lower contrast is high. And it is difficult to balance speed and accuracy during on-orbit ship detection. To solve the above problems, an improved lightweight ships detection method (ImShips) based on YOLOv5s is proposed. Firstly, the standard convolution with small receptive field is adopted at the bottom of the baseline to obtain spatial information of small ships. And the dilated convolution with enlarged receptive field is added at the top of the baseline to preserve more semantic features, which is conducive to extract large targets feature. Then, a lightweight channel attention mechanism is applied to the backbone and neck of YOLOv5. And the weight is allocated to filter more important texture information. Finally, the depth-wise separable convolution is adopted to replace the standard convolution during down-sampling to reduce the number of parameters and improve the inference speed. Compared with YOLOv5s model, the experimental results show that ImShips achieves an increase in AP, while the FLOPs are reduced by 45.61%, and the speed is increased by 8.31% in SSDD and ISSID datasets. The speed and accuracy of ImShips model are improved effectively for sea surface object detection. The proposed method has great application potential in on-orbit ship detection.
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YUE Wen-Cheng, WANG Qing, LI Xin-Yu, WANG Shu-Xiao, YU Ming-Bin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The realization of subwavelength mode confinement is mainly based on surface plasmon polaritons. Due to metallic ohmic loss, plasmonic waveguides usually have larger propagation loss. Here, an all-dielectric anti-slot waveguide was proposed, which can realize subwavelength mode confinement and theoretically lossless propagation simultaneously. A normalized mode area of 3.4×10-2 was achieved in the all-dielectric anti-slot waveguide. Moreover, an efficient coupling scheme between the small-size anti-slot waveguide and input/output fiber was proposed. An overall coupling efficiency of 92.7% was attained. The misalignment tolerance for 1 dB loss penalty was about 2 μm in both y and z directions.
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LIU Si-Yu, ZHANG De-Hai, MENG Jin, JI Guang-Yu, ZHU Hao-Tian, HOU Xiao-Xiang, ZHANG Qing-Feng
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A sub-harmonic monolithic mixer with a center frequency of 0.825 THz is developed based on GaAs monolithic microwave integrated circuit technology. The parasitic parameters of the anti-parallel Schottky diode at the terahertz frequency are analyzed to improve the circuit design. The monolithic circuit is suitable for terahertz devices with the characteristics of high integration and little fabrication deviation. Meanwhile， the beamlead circuit is used to reduce the loss of substrate and installation position offset. Measured results show that the single-sideband （SSB） conversion loss of the mixer is lower than 33 dB in the frequency range 0.81–0.84 THz， and the minimum SSB conversion loss is 28 dB.
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GU Yu-Qiang, TAN Ming, WU Yuan-Yuan, LU Jian-Ya, LI Xue-Fei, LU Shu-Long
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this paper， the trade-off between gain-bandwidth product （GBP） and dark current of an InAlAs/InGaAs avalanche photodiode （APD） was studied by optimizing multiplication layer. An optimized multiplication layer with 200 nm was proposed to improve the GBP and reduce the dark current. The fabricated InAlAs/InGaAs APD shows an excellent performance which is consistent with the calculated results. A high responsivity of 0.85 A/W （M=1） at 1.55 μm and a high GBP of 155 GHz was achieved， whereas the dark current is as low as 19 nA at 0.9 Vb. This study is significant to the future high-speed transmission application of the avalanche photodiodes.
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YANG Yu, ZHAO Shuai, SHEN Yuan, MENG Ling-Jun, WANG Meng-yu, ZHANG Lei, WANG Ke-Yi
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The whispering gallery mode （WGM） micro-resonator is an ideal platform for investigating the nonlinear light phenomenon. In this article， we achieved up to the fifth-order cascaded stimulated Brillouin scattering （SBS） light in a CaF2 micro-disk resonator with an mm-sized 12.6 mm diameter and an ultra-high quality factor （
factor） at 1550 nm wavelength. We found that there are multi modes of families in our large-scale micro-disk resonator when coupled to an adiabatic tapered fiber， which can easily select resonances matching the SBS frequency shift. This can eliminate the requirement that precisely controlling the scale of the resonator to match the free spectral range （FSR） with the Brillouin frequency shift. During our experiment， to solve the environmental fluctuation problem between the micro-disk resonator and tapered fiber， we designed a packaged platform that can steadily seal the resonator and tapered fiber in an N2 atmosphere. The generated cascaded Brillouin light and the stable packaged platform can further be used to investigate the multi-wavelength Brillouin laser and Brillouin light-based gyroscope. -
MIAO Zhuang, ZHANG Yong, Li Wei-Hua
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A real-time target detection method based on center points is proposed for infrared imaging systems equipped with CPUs. Following the lightweight design principles, a backbone with low computational costs is first introduced for feature extraction. Correspondingly, an efficient feature fusion module is designed to exploit spatial and contextual information extracted from multi-stages. In addition, an auxiliary background suppression module is proposed to predict foreground regions to enhance the feature representation. Finally, a simple detection head predicts the target center point and its associated properties. Evaluations on the infrared aerial target dataset show that our proposed method achieves 90.24% mAP at a speed of 21.69 ms per frame on the CPU. It surpasses the state-of-the-art Tiny-YOLOv3 by 10.16% mAP with only 21% FLOPs and 11% parameters while also runs 10.02 ms faster. The results demonstrate its great potential for real-time infrared applications.
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HE Wan-Ting, ZHANG Bo, WANG Bin, SUN Xiao-Wei, YANG Ming-Hui, WU Xiao-Feng
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The concealed object detection in millimeter wave (MMW) image is of great significance in non-contact body inspection. At present, MMW radar has been able to obtain three-dimensional images, which are usually simply compressed into two-dimensional images in current methods. However, such methods have not fully considered the depth direction information, resulting in a bottleneck of detection accuracy. To address this issue, a novel framework for MMW image concealed object detection is proposed, which can make the most of the internal logic relations of various features along the depth direction. The framework consists of a Convolutional Neural Network (CNN) and a Long Short-Term Memory (LSTM) network. The former is used to extract the multi-level feature on the cross-section. The latter is used to integrate the global correlation between the above features of the depth direction, so as achieving feature-level information fusion and improve the accuracy of 2D location prediction. Experimental results show that the proposed method achieves remarkable results comparing to the known detection method based on 2D MMW images.
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Dai Zhen-Bing, Luo Guo-Yu, He Yan, Wang Chong, Yan Hu-Gen, Li Zhi-Qiang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Single crystal of tungsten ditelluride (WTe2) is a transition metal dichalcogenide which displays a wide range of electronic properties, such as non-saturable magnetoresistance. Both theoretical predictions and experimental measurements describe that WTe2 is a new topological state of matter called type-II Weyl semimetal with tilt Weyl cones. Things become even more interesting when its thickness is reduced to a single layer. For example, monolayer WTe2 with 1T’ structure is a class of large-gap quantum spin Hall insulators which exhibit a helical one-dimensional edge mode. This structural distortion causes an intrinsic band inversion between chalcogenide-p and metal-d bands, spin-orbit coupling then opens up a band gap large enough to realize quantum spin Hall effect at temperatures below about 100 K. Optical measurements provide a powerful tool to investigate electronic structure which complements photoemission and tunneling measurements due to its sensitivity to the role of electronic interactions in solids. Among many kinds of optical techniques, scattering-type scanning near-field optical microscopy (SNOM) is a powerful tool for nanostructure investigation, which consists of a laser coupled to a metal-coated tip and probe the local electric field in a close proximity to the sample. This technique provides information about the complex optical properties of the sample of nanoscale resolution. Here we use SNOM to study the near-field optical response of WTe2 thin films, we have observed bright fringes near the edge of the thin film sample and also a thickness dependence on optical contrast to the sample and substrate. To understand this behavior, first we obtain the dielectric function of WTe2 at room temperature by Drude-Lorentz model via fitting the infrared radiation (IR) reflectance and conductivity spectra, then the near-field ratio of thin film sample to the diamond substrate is calculated by the Finite-dipole model. The experimental result reveals that the behaviour of the sample cannot be fully described by the bulk properties. We assume that a decoupled thin layer exists on the surface of the bulk. There are two possible explanations for the observation of the near-field patterns of bright outside fringes. Firstly, a hot-spot field may be produced between the tip and the sample edge due to the enhancement of the local electric field under the IR illumination, a similar behavior has been revealed in surface-metallic black phosphorus. Another probability is that the topological edge states of top decoupled monolayer WTe2 lead to an enhancement of the local optical conductivity. This work provides a reference from the optical research of topological materials in the future.
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YOU Ming-Hui, ZHU Xuan-Yu, LI Xue, LIU Guo-Jun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The epitaxial growth of GaSb on GaAs substrate was studied by using interface mismatch arrays （IMF）. The effects of growth temperature， Sb： Ga effective atomic flux ratio， thickness of AlSb transition layer and GaSb epitaxial layer on the structural quality of the material were studied. High Resolution X-ray Diffraction （HRXRD） study shows that the FWHM of the diffraction peak measured by HRXRD was very sensitive to the changes of above parameters， while the effective atomic flux ratio （EFF） of Sb： Ga was the most important factor. The FWHM value of GaSb diffraction peak changes slightly with the increase of thickness， but the structural quality of GaSb layer improves with the increase of thickness. The results show that the optimum growth temperature of GaSb is 515℃， the optimum thickness of AlSb transition layer is 5 nm. The 10 nm thick GaSb epitaxial layer was prepared and characterized specifically. The results show that the FWHM value of the diffraction peak is only about 15 arcsec， which is equivalent to that of commercial GaSb substrate. The electron mobility of the quantum Hall device is as high as 1.5×105 cm2/Vs at 1.8 K under zero bias， which attains to the level of device performance on GaSb substrate.
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YANG Chen, GUO Wei, LI Zhi-Xian, JIAO Meng-Long, ZHANG Zhi-Qiang, LUO Ji-Run, ZHU Min
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Based on the theory of open resonant cavity and quasi-optical mode conversion， a high-order quasi-optical mode generator was designed and manufactured for the cold measurement of the gyrotron oscillator. For the high-order mode generator working at 140 GHz and TE28，8 mode， the corresponding experimental measurements was completed using the three-dimensional mobile measurement platform and the network analyzer which were controlled by computer programming. The results show that， when the simulation results related to the resonant frequency， Q factor， and the correlation of the electric field distribution with the TE28，8 mode in the cavity are respectively 140.179 GHz， 855， and 90.9%， the corresponding cold-tested ones for resonant frequency and Q factor are respectively 140.155 GHz and 876， and the transverse electric field distribution tested is very similar to that of the TE28，8 mode， which indicates that the quasi-optical mode generator designed in this paper can provide an effective experimental platform for the research and design process verification of the high-order body mode gyrotron oscillator.
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QU Yang, HUANG Xiao-Xian, FENG Qi
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Chinese ocean color and temperature （COCTS） was interfered by the unknown radiation of cold space when the satellite of HY-1B was in orbit， which causes its nine-year data to be affected to varying degrees. Using data with less impact on the two poles as samples， the response repair model based on recalibration coefficients and the non-uniform correction model based on probability distribution were established to repair the earth target signal， and the repair results were compared and optimized. The accuracy and stability of model were verified. The final results show that under the condition of the cold space radiation benchmark is affected， the response repair model combined with the probability distribution correction model can obviously repair the data effectively.
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LANG Xing-Kai, JIA Peng, QIN Li, CHEN Yong-Yi, LIANG Lei, LEI Yu-Xin, SONG Yue, QIU Cheng, WANG Yu-Bing, NING Yong-Qiang, WANG Li-Jun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In order to obtain high power, narrow line width and near diffraction limit output semiconductor laser diodes, the high order Bragg gratings (HOBGs) and master oscillator power-amplifier (MOPA) have been fabricated in the waveguide of HOBGs-MOPA laser diodes with an emission wavelength of 980 nm. The longitudinal mode of HOBGs-MOPA was selected by a HOBGs with a period of 11.37 μm. The single-mode optical power is amplified by a tapered waveguide with an angle of 6°. In this paper, we present a single mode laser diode with continuous wave power 2.8 W at a 3 dB line-width of 31 pm. The laser diode operates in a close to diffraction-limited optical mode (M2=2.51, laterally).
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LI Huai-Qian, YANG Ming-Hui, WU Liang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The difference in projection angle leads to changes in the shape and size of objects， which limits the improvement of the detection performance of small objects by the two-dimensional （2D） concealed object detection method based on projected views of active millimeter wave （AMMW） holographic images. For this reason， a three-dimensional （3D） concealed object detection method based on point clouds was proposed for the first time. AMMW holographic images were converted into point clouds by thresholding， and then input into the 3D object detector SECOND， which was improved by dilated convolution and multi-branch structure， to extract the 3D geometric understanding of the objects and their multi-scale context information to improve the detection ability for small objects. The experimental results showed that compared with the projection-based 2D detection methods， the average recall （AR） of this method was improved by 3.33%， which proved the effective improvement of localization accuracy. The detection rate and the average precision （AP） was relatively improved by 8.75% and 7.11%， and the false alarm was reduced by 1.78% at an intersection over union （IOU） threshold of 0.5. The average AP under different IOU thresholds was improved by 4.30%. The detection accuracy was effectively improved. The detection speed was 17.3 FPS， which reached the real-time level.
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Su Jinlong, Hu Fei, Tian Yan, Zheng Tao, Hu Yan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Materials samples of some common military coating including radar absorbing coating， high emission infrared coating， radar absorbing and high emission infrared compatible coating， radar absorbing and low emission infrared compatible coating， and aviation anticorrosive coating are prepared and their emissivity at different observation angles in Ka band is measured in this paper. An improved measurement scheme based on voltage method is proposed and used for the measurement experiments， which aims at eliminating the error from the antenna beam cannot be completely covered by the samples of materials to be measured and inconsistency of thickness between the reference bodies and the samples. In addition， the main sources of measurement uncertainty are analyzed and discussed.
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ZHENG Fu-Qiang, KUANG Ding-Bo, HU Yong, GONG Cai-Lan, HUANG Shuo, LI Lan, HE Zhi-Jie
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The accuracy of independent sea ice identification in the Arctic sea ice region has important guiding significance for ensuring navigation safety, planning Arctic routes and dynamically correcting route. The image of FY-3 satellite MERSI II has a spatial resolution of 250m. Compared with SAR image, it has the characteristics of larger size, shorter revisit period and lower cost. As an ideal data source for dynamic identification of isolated Arctic sea ice, it can provide information about the ice conditions over large areas. To some extent, the traditional sea ice identification method based on optical remote sensing data sources are unable to distinguish the thin ice areas mixed with independent sea ice, small ice debris and ice water. Using this method, the segmentation effect on edge and small pieces of independent sea ice is poor, and independent sea ice covered by thin clouds cannot be identified. For this reason, based on the characteristics of the FY-3 MERSI II images, an algorithm of independent sea ice segmentation based on U-ASPP-Net is proposed. The algorithm introduces the Atrous Spatial Pyramid Pooling module and Atrous Depthwise Separable Convolution on the basis of U –Net to develop a new independent sea ice segmentation network U-ASPP-Net. Meanwhile, FDWloss is used as the loss function at the back end of the network. Finally, the overlap elimination strategy is used to generate the final independent sea ice segmentation map. In order to verify the accuracy and effectiveness of U-ASPP-Net, U-Net, Deeplab v3+ and partition gradient difference and bimodal threshold segmentation method are selected as control methods for experiments. The experimental results show that the independent sea-ice fine segmentation method based on U-ASPP-Net is superior to other methods in the four indexes of OA, Kappa coefficient, IOU, Dice coefficient. It has a strong ability to extract details and edges, and has a high degree of reduction to tiny sea ice. In addition, this algorithm can solve the problem of thin cloud interference that cannot be solved when extracting independent sea ice based on medium-resolution remote sensing images to a certain extent. It still has a good ability to extract sea ice under thin clouds and can provide more accurate technical support for the dynamic planning of the Arctic route.
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Chu Yuan-Yuan, Liu Ying-Mei, Li Sheng-Juan, Xu Zhi-Cheng, Chen Jian-Xin, Wang Xing-Jun
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The phonon anharmonic effect caused by Sb in GaAsSb/InP heterojunction with different Sb components has been studied by measuring Raman spectra at 3K ~ 300K. It is found that with the decrease of temperature， the peak position of long optical phonon moves to the high wave number， and the change tends to be gentle when the temperature is lower than 100K. The relationship between the optical phonon and temperature is simulated by using the three-phonon model and the four-phonon model， respectively. Compared with the experimental results， the four-phonon model agrees better with the experimental data， which indicates that the change of the temperature dependent Raman scattering peak position must consider the four-phonon anharmonic vibration. Compared with the lattice mismatched samples S1 （Sb=37.9%） and S3 （Sb=56.2%）， the phonon anharmonic obtained in the lattice matched sample S2 （Sb=47.7%） is the smallest， and the phonon lifetime in S2 is the longest by the study of phonon linearly. The phonon anharmonic effect and phonon lifetime of GaAsSb crystal lattice vibration are not only affected by the disordered scattering of the alloy， but also by the line defects and phonon scattering of the defects introduced by the mismatch with the substrate.
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TANG Guo-Liang, LI Chun-Lai, LIU Shi-Jie, XU Rui, XU Yan, YUAN Li-Yin, WANG Jian-Yu
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Based on the noise suppression effect of weighing measurement principle , a short-wave infrared spectral imaging method based on S-matrix slit array were proposed . By constructing S-matrix slit array to replace the single slit of spectral imaging system , the alias measurement of spatial and spectral information was realized . The detector noise and photon noise of the system was analyzed and the noise suppression effect was calculated . The simulation results show that this method can effectively reduce the noise level and improve the imaging quality of low light conditions . The principle prototype was built for imaging experiment . The imaging target was a homogeneous object . By comparing the imaging data onto a single slit , the spectral imaging method of the S-matrix slit array was used to increase the SNR by 9% and 21% respectively under 23% and 10% detector potential well light intensity .
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LI Jin-Jin, QIU Shi, ZHANG Yu, GAO Cai-Xia, QIAN Yong-Gang, LIU Yao-Kai
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Nighttime satellite sensors have limited radiometric accuracy of due to their lower signal-to-noise， large straylight impact. And their own particularities make themselves larger limitations on on-orbit calibration. Based on the characteristic of anisotropic reflectance of nighttime TOA （top-of-atmosphere）， a new method was proposed to evaluate the accuracy of on-orbit radiometric calibration of nighttime sensors using a relative accurate simulation of the nighttime radiative transfer. Specially， the Antarctic Dome C site was selected as the study area， and the nighttime on-orbit radiance was simulated by the MT2009 （Miller-Turner 2009） TOA lunar irradiance model and TOA BRDF （Bidirectional Reflectance Distribution Function） model. After the analysis of the consistency of VIIRS DNB （Visible Infrared Imaging Radiometer Suit Day/Night Band） observed and simulated radiance under same geometry， it was found that their differences were about 4.97×10-10W?cm-2?sr-1 one order of magnitude blow the minimum detection threshold of VIIRS DNB （3×10-9W?cm-2?sr-1） during 2018~2020. So there are good performance of on-orbit radiometric calibration of VIIRS DNB on SNPP and NOAA-20 based on the error range of acceptable instrument sensitivity. Besides， an evaluation of on-orbit radiometric calibration stability of VIIRS DNB was conducted based on the distance-corrected radiance of SNPP VIIRS DNB and NOAA-20 VIIRS DNB. And it was found that when under the same lunar phase angle， the VIIRS DNB radiance kept a good consistency within 6% between SNPP and NOAA-20.
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ZHANG Li-Bo, WANG Lin, XING Huai-Zhong
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In recent years, two-dimensional layered materials, such as graphene, black phosphorus, transition metal dichalcogenides, etc., have attracted the attention of researchers in the relevant areas due to unique electronic and optoelectronic properties. Regardless of dangling bonds and lattice mismatch in surface, two-dimensional material has a great degree of freedom to form a van der Waals heterojunction with similar materials. Here, a graphene-black arsenic van der Waals heterostructure is fabricated by the fixed-point transfer technology, realizing the broadband detection from visible light-infrared-microwave. Among them, the photoexcited electron-hole pairs generated in the black arsenic are separated and injected into the graphene under visible and infrared light radiation, which significantly reduces the potential barrier between the semiconductor black arsenic and the gold electrode, thereby realizing effective photocurrent extraction. In the microwave band, due to the difference in the Seebeck coefficient of the two materials, the non-equilibrium carriers are generated due to the photothermoelectric effect, forming the photocurrent under zero bias. The research results paved the way for bandgap engineering of two-dimensional layered materials to be applied to the fields of photonics and optoelectronics.
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WANG De-Tang, REN Zhi-Gang, LIU Sha, ZHAO Yong-Qiang, FANG Hui, ZHANG Lian-Dong
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Due to the heterogeneous characteristics of the infrared polarization focal plane， it is necessary to take into consideration the impact of the response differences in different bias channels on the overall correction effect in the process of non-uniform correction. The non-uniform correction problem of the infrared polarization focal plane is more complex than that of the ordinary homogeneous infrared focal plane. For non-uniformity correction of polarization focal plane， an algorithm based on scene-based polarization redundancy estimation is proposed. The statistical information between acquired images and estimated images from polarization redundancy is acquired， then the differences in the response of all pixels in the whole focal plane are obtained. By comparing and analyzing the differences from two directions in each polarization channel， we can obtain the updated gain correction coefficients. Then radiometric recalibration is used to suppress the ghost image caused by the static scene， and the gain correction coefficients in the current state are obtained. In this process， the gain correction coefficients are updated adaptively by evaluating the previous correction coefficients through polarization redundancy estimation. Finally， experiments on the real scene data demonstrate the effectiveness of the proposed non-uniformity correction algorithm for polarization images.
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HUANG Wei-Guo, GU Yi, JIN Yu-Hang, LIU Bo-Wen, GONG Qian, HUANG Hua, WANG Shu-Min, MA Ying-Jie, ZHANG Yong-Gang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
InAs/In0.83Al0.17As quantum wells have been demonstrated on In0.83Al0.17As metamorphic layers on GaP/Si substrates. The effects of GaxIn1-xP and GaAsyP1-y graded buffer layers on the sample performances are investigated. The sample with GaxIn1-xP metamorphic buffer layer has narrower width in X-ray diffraction reciprocal space maps， indicating less misfit dislocations in the sample. Mid-infrared photoluminescence signals have been observed for both samples at room temperature， while the sample with GaxIn1-xP metamorphic buffer shows stronger photoluminescence intensity at all temperatures. The results indicate the metamorphic buffers with mixed cations show superior effects for the mid-infrared InAs quantum wells on GaP/Si composite substrates.
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DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this paper， two millimeter-wave zero-bias Schottky detectors for the direct detection system of the CubeSat radiometer， with center frequencies of 89 GHz and 150 GHz， respectively， were designed and implemented. These designs were based on zero-bias Schottky diodes of ACST. A radial stub structure was adopted at the DC ground and output port with a tuning line for optimum impedance matching to achieve stable and high performance and broadband characteristics； this structure also makes the circuit easier to integrate with pre-level systems and more suitable for CubeSat radiometer miniaturization. Circuit structure and Schottky diode were analyzed， modeled， and optimized to obtain better performance. The results showed that the W-band detector has a typical sensitivity of about 2500 V/W in the range of 85 GHz to 95 GHz and a linearity of 0.9994 at 89 GHz. Moreover， the D-band detector has a typical sensitivity of about 1600 V/W in the range of 145 GHz to 155 GHz and a linearity of 0.9992 at 150 GHz. These results verified the advantages of the improved circuit structure in the detector and the feasibility of the direct detection system.
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LIU Yi-Ming, ZHANG Lei, ZHOU Mei, LIANG Jian, WANG Yan, SUN Li, LI Qing-Li
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
The suspended sediment concentration （SSC） is an extremely important property for water monitoring. Since machine learning technology has been successfully applied in many domains， we combined the strengths of empirical algorithms and the artificial neural network （ANN） to further improve remote sensing retrieval results. In this study， the neural network calibrator （NNC） based on ANN was proposed to secondarily correct the empirical coarse results from empirical algorithms and generate fine results. A specialized regularization term has been employed in order to prevent overfitting problem in case of the small dataset. Based on the Gaofen-5 （GF-5） hyperspectral remote sensing data and the concurrently collected SSC field measurements in the Yangtze estuarine and coastal waters， we systematically investigated 4 empirical baseline models and evaluated the improvement of accuracy after the calibration of NNC. Two typical applications of NNC models consisting baseline model calibration and temporal calibration have been tested on each baseline models. In both applications， results showed that the calibrated D’Sa model is of highest accuracy. By employing the baseline model calibration， the root mean square error （RMSE） decreased from 0.1495 g/L to 0.1436 g/L， the mean absolute percentage error （MAPE） decreased from 0.7821 to 0.7580 and the coefficient of determination （R2） increased from 0.6805 to 0.6926. After implementation of the temporal calibration， MAPE decreased from 0.8657 to 0.7817 and R2 increased from 0.6688 to 0.7155. Finally， the entire GF-5 hyperspectral images on target date were processed using the NNC calibrated model with the highest accuracy. Our work provides a universal double calibration method to minimize the inherent errors of the baseline models and a moderate improvement of accuracy can be achieved.
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WANG Xi, YE Qing, DONG Xiao, LEI Wu-Hu, LYU Tong-Lin, GUO Yan-Tin, HU Yi-Hua
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
It has very important application value to investigate the damage performance of PbS detector irradiated by mid-infrared laser. In this paper， the experiment research on damage in PbS detector irradiated by 2.79 μm mid-infrared laser is carried out. Furthermore， the theoretical model of PbS detector irradiated by 2.79 μm laser is developed and a numerical simulation is performed to calculate temperature distribution in PbS detector using finite element method， and the relationship between laser parameters and damage effect is also studied. The simulation and experimental results indicate that the damage mechanism of PbS detector irradiated by 2.79 μm mid-infrared laser is mainly melting damage， and the melting damage threshold is calculated to be 13.03 J/cm2. Before the temperature reaches the melting point of PbS， the thermal decomposition reaction of PbS begins， and then separates out PbO which is the yellow precipitate. It is shown that pulse repetition frequency and the number of pulses affect damage considerably， and the accumulation of multi-shot laser induced damage in PbS detector is obvious. The theoretical analysis is in agreement with the initial damage morphology of PbS surface.
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DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Based on TE01 circular electric mode， the elliptical quasi-optical mode converter is studied， and a modified formula for rapidly designing elliptical-structure quasi-optical system is proposed. The quasi-optical system designed by the modified formula is composed of an elliptical Vlasov launcher and a quasi-paraboloidal mirror. The simulation results show that the beam launched by the elliptical system has the characteristics of better launcher directionality and lower side-lobe gain， and its size is smaller than the traditional circular system.
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WANG Tian-Ye, FEI Qi-Lai, XU Bo, LIANG Yan, ZENG He-Ping
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
InGaAs/InP avalanche photodiodes （InGaAs/InP APDs） are capable of detecting single photons in the near infrared. With advantages of high integration and low power consumption， they are widely used in quantum information science， laser mapping， deep space communication and other fields. In order to reduce error counts， InGaAs/InP APDs are generally operated in gated Geiger mode， where the repetition frequency of the gated signal directly determines the detector"s working rate. Thus， we adopt a low-pass filtering scheme to build a high-performance InGaAs/InP single-photon detector with adjustable GHz repeating frequency by integrating the processing circuit with GHz sine gating signal generation， avalanche signal acquisition， temperature control， bias voltage regulation and other functions. When the frequency of GHz gating signal increases to 2 GHz， its phase noise is still better than the -70 dBc/Hz@10 kHz， and the peak noise is suppressed to the level of thermal noise. When the detection efficiency is 10%， the dark count is only 2.4×10-6/ gate. In addition， we also verify the long-term stability of the detector under this scheme， and test the influence of working rate， bias voltage and other factors on the key performance parameters of APD， laying a foundation for the further integration and promotion of GHz InGaAs/InP APD.
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FU Juan-Juan, TANG Jin-Lan, BAO Yi-Lin, SHANG Hui, WU Jin-Jin, WANG Xiao, YIN Jian-Hua
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
An innovative reflective near-infrared （NIR） fiber probe with flexibility and convenience was designed for biomedical in-situ detection. When the brand-new fiber probe structure and fiber arrangement were designed， further， a gradient-index （grin） lens was coupled to the top of the reflective NIR fiber bundles to make it have higher measurement accuracy and collection efficiency. When measuring NIR spectra of sucrose samples by coupling the grin NIR fiber probe to Fourier transform near infrared spectrometer， it was found that the grin NIR fiber probe had the advantages of convenience， high efficiency and spectral repeatability and SNR. The NIR spectra of articular cartilage at the femoral end of the canine knee joint were measured in situ by the grin NIR fiber probe and were preprocessed by first-derivative quadratic polynomials 21-point Savitzky-Golay smoothing for principal component analysis and Fisher discrimination analysis （PCA-FDA）. The correct recognition accuracies of PCA-FDA model in initial cases and cross validation cases were 97.62% and 90.47%， respectively， as well as 96.43% for the prediction set， which confirms the effectiveness of NIR fiber probe detection in situ and the feasibility of osteoarthritis recognition and lays the foundation for basic research and early clinical diagnosis of osteoarthritis.
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LUO Yan, HAO Yong-Qin, YAN Chang-Ling
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A high-refractive-index contrast subwavelength grating （HCG） for 940 nm GaAs-based VCSEL is reported. The reflector is composed of GaAs and AlOx. The effects of the grating parameters of TE-HCG on refractivity are discussed in detail. And the structural characteristics of TE-HCG and TM-HCG are analyzed， especially the influence of their topography errors on the high reflection band. The 940 nm TE-HCG has a large reflection bandwidth of up to 97 nm with its reflectivity for TE incident light more than 99.5%， and the ratio of Ratio of high reflection band to central wavelength is more than 10%. But for TM incident light its reflectivity is less than 90%. It is worth mentioning that the VCSEL with such a TE-HCG can be prepared by one-time epitaxial growth technology， which helps to improve the performance of the device. Furthermore， it greatly reduces the manufacturing difficulty and cost of a VCSEL.
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CUI Wei-Xin, LI Xiang, SUN Hao, XU Zeng-Chuang, LI Yong, YU Yuan-Hang
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
Aiming at the phenomenon of non-uniformity change caused by on-orbit temperature change of the high-orbit area array infrared earth sensor， an optical-mechanical implementation scheme for on-orbit non-uniformity calibration is proposed. The miniaturized， lightweight， and long-life optomechanical system includes calibration blackbody components and optical imaging systems. The system includes surface source blackbody， motion control mechanism， and optical imaging system. Based on the analysis of the necessity and mechanism of system non-uniformity correction， the relationship between the selection and design of surface source blackbody， motion control mechanism and optical system is studied， and the simulation design of each group of components is realized. Based on simulation results， the effects and advantages of system heterogeneity calibration are analyzed and compared. The effect of the heterogeneity of the system is evaluated by using the orbiting earth imaging data， and the evaluation results show that the requirements for on-orbit application are met.
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DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this work， the surface treatment of InAs/GaSb type-II super-lattice long-wavelength infrared detectors is studied. An optimizing process of N2O plasma treatment and rapid thermal annealing was developed， which can improve the performance of long-wavelength detector with λ50% cut-off=12.3μm from 5.88 ×10-1A/cm2 to 4.09 ×10-2A/cm2 at liquid nitrogen temperature， -0.05V bias. Through variable area device array characterization， the sidewall leakage current was extracted. Under zero bias， the surface resistivity improved from 17.9Ωcm to 297.6 Ωcm. However， the sidewall leakage couldn’t be ignored under large inverse bias after optimizing process， where surface charge might induce the surface tunneling current. It is verified by gate-control structure that there are two main leakage mechanisms in long-wave device： pure sidewall parallel resistance and surface tunneling. At last， the surface charge was calculated to be 3.72×1011cm-2 by IV curve fitting after optimizing process.
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Shi Rui, Zhou Jian, Bai Zhi-zhong, Xu Zhi-cheng, Zhou Yi, Liang Zhao-ming, Shi Ying, Xu Qing-qing, Chen Jian-xin
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
In this paper， the multi-coatings composed of layers of zinc sulfide and germanium was designed and fabricated on a long-wavelength InAs/GaSb Type-II superlattices infrared focal plane arrays （FPAs）. Compared with the FPAs without multi-coatings， the multi-coatings makes the response peaks of the FPAs shift from the wavelength of 8.7 and 10.3 μm to that of 9.8 and 11.7 μm. The 50% response cut-off wavelength of the FPAs shifts from 11.6 μm to 12.3 μm， and the response intensity of the FPAs is increased by 69% at the wavelength of 12 μm. In summary， the multi-coatings make the response wavelength of the FPAs tunable， which provides a powerful platform for more sensitive long-wave detection and improving imaging capabilities.
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HUANG Hui-Lin, HUANG Jing, SHI Quan
DOI: 10.11972/j.issn.1001-9014.XXXX.XX.001
Abstract:
A millimeter wave equivalent circuit model parameters extraction method for Schottky diodes is proposed in this paper. The pad capacitance has been determined by using open circuit test structure, and the feedline inductance has been determined by using short-circuit test structure. The parasitic resistance has been extracted by using DC method and AC method respectively. An excellent fit between measured and simulated S-parameters in the frequency range of 1-40 GHz is obtained for GaAs Schottky diode．
Volume 40,2021 Issue 5
40周年特邀
遥感技术与应用
Infrared Photoelectric Technology and Application
Terahertz and Millimeter Wave Technology
Infrared Materials and Devices
Terahertz and Millimeter Wave Technology
红外材料与器件
遥感技术与应用
Terahertz and Millimeter Wave Technology
红外光谱与光谱分析
Terahertz and Millimeter Wave Technology
红外光谱与光谱分析
40周年特邀
太赫兹与毫米波技术
红外材料与器件
遥感技术与应用
红外材料与器件
Terahertz and Millimeter Wave Technology
Infrared Materials and Devices
Infrared Photoelectric Technology and Application
Terahertz and Millimeter Wave Technology
红外光谱与光谱分析
红外材料与器件
Terahertz and Millimeter Wave Technology
遥感技术与应用
Infrared Materials and Devices
图像处理及软件仿真
Terahertz and Millimeter Wave Technology
遥感技术与应用
红外光谱与光谱分析
Infrared Photoelectric Technology and Application
遥感技术与应用
太赫兹与毫米波技术
图像处理及软件仿真
Infrared Materials and Devices
Terahertz and Millimeter Wave Technology
遥感技术与应用
Infrared Photoelectric Technology and Application
Terahertz and Millimeter Wave Technology
Infrared Photoelectric Technology and Application
红外光谱与光谱分析
Infrared Photoelectric Technology and Application
Infrared Materials and Devices
红外光谱与光谱分析
Infrared Materials and Devices
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Research on millimeter-wave ridged half-mode waveguide filter based on periodic defected ground structure
Abstract:
A monolithic ridged half-mode waveguide bandpass filter with a periodic defected ground array has been successfully fabricated. Utilizing the high-pass characteristic of the waveguide and the rejection band generated by the periodic defected ground structure, an effective passband was created. The measured results show a 3 dB passband from 39.4 to 45.4 GHz, centered at 42.4 GHz with a 3-dB fractional bandwidth of 14.1%. The lowest insertion loss of 2.4 dB locates at 44.2 GHz. The suppression in upper rejection band reaches 40 dB at 58 GHz. Compared to conventional rectangular waveguide filters, the width of the proposed filter is reduced by 64%, which benefits to the integration and miniaturization. With the development of the next generation wireless communication (5G) towards millimeter-wave band, the miniaturized millimeter-wave filter has promising potential for 5G communication.
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Highly Sensitive Graphene Terahertz Detection Driven by two-dimensional Ferroelectrics
WANG Xue-Yan, Zhang Yi-Wen, Wang Lin, Chen Xiao-Shuang
Abstract:
Graphene has the excellent characteristics of low defect density, easy large-area transfer and high carrier mobility. However, the zero-bandgap band structure of graphene leads to a short lifetime of photogenerated carriers, which restricts its application in highly sensitive photodetectors. In this work, ferroelectric material CuInP2S6(CIPS) was used as the top gate to control the photoelectric characteristics of graphene, and the possibility of improving the sensitivity of graphene terahertz detector was explored. The detection mechanism of graphene photothermoelectric effect and plasma wave effect under ferroelectric control was studied, and a high-performance graphene detector was obtained. At 0.12 THz, the responsivity of detector at room temperature reaches 0.5 A/W, with the response time of 6.3 μs and the noise equivalent power(NEP) of 0.81 nW/Hz1/2 under a bias voltage of 40 mV and a gate voltage of 2.12 V. At 0.29 THz, the responsivity is determined to be 0.12 A/W, and a NEP is 1.78 nW/Hz1/2. This work demonstrates the great potential of two-dimensional ferroelectric heterostuctures at THz band.
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Relationship between radar reflectivity factor and ice water content of non-spherical cirrus ice crystals at 220 GHz
WANG Biao, HUO Yi-Wei, GUO Xing, WU Jia-Ji
Abstract:
For the practical needs in the data processing of terahertz radar，the discrete dipole approximation method is used to calculate the backscattering cross-section of non-spherical ice crystals with different shapes. Based on the latest refined ice cloud model, the relationship between the radar reflectivity factor Zm and ice water content I in 220 GHz is established. The calculation results show that both the shape of the non-spherical ice crystals and the ice cloud model have a particular influence on the Zm-I relationship. This study has application value for cloud parameter inversion of mid-latitude cirrus clouds, and it can be helpful for the development of terahertz radar in the detection of clouds.
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Infrared image dehazing based on hierarchical subdivision superpixels and information integrity prior
LI Wei-Hua, LI Fan-Ming, MIAO Zhuang, TAN Chang, MU Jing
Abstract:
Hazy weather degrades the contrast and visual quality of infrared imaging systems due to the presence of suspended particles. Most existing dehazing methods focus on enhancing global image contrast or exploit a local grid window strategy, which may lead to loss of information, halo artifacts and distortion in sky region. To address these problems, this paper proposes a novel single image dehazing model based on superpixel structure decomposition and protection of information integrity. In this model, based on the local structure information, the image is first adaptively divided into multiple objective regions using a superpixel segmentation algorithm to eliminate halo artifacts. Meanwhile, to avoid the error estimate caused by the local highlighted targets, a modified quadtree subdivision based on superpixel blocks is applied to obtain the global atmospheric light. Furthermore, a combined constraint is used to optimize the transmission map by minimizing the loss of information. Compared with state-of-the-art methods in terms of qualitative and quantitative analysis, experiments on real-world IR image data demonstrate the efficacy of the proposed method in both contrast and visibility.
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Distortions of terahertz pulses induced by the air coherent detection technique
Abstract:
Terahertz air coherent detection technique is a broadband detection method, which has been widely used in the broadband terahertz technology after its demonstration in the experiment. The frequency response of this method is determined by the duration of the probe laser pulse. Thus, the different probe lasers might induce distortions of terahertz pulses during the detection process. In this paper, the distortions and the energy loss of the terahertz pulses induced by the air coherent detection technique are quantitatively investigated based on the simulations. The results show that the pulse distortions and the energy loss depend on the duration of the probe laser pulse and the central frequency of terahertz pulse to be detected. This work will help to estimate the influence of the air coherent detection technique in the broadband terahertz technology.
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A Wideband Injection-Locked Frequency Tripler
Abstract:
A wideband injection-locked frequency tripler (ILFT) is proposed. Based on the conventional injection method, the tripler used a push-push differential pair to double the frequency of the input signal and coupled the generated second harmonic to the source common mode node of the injectors through a transformer, which enhanced the second harmonic at the source common mode node of the injectors. Since the injection current is generated by mixing the injected signal with the second harmonic at the source common mode node, the injection current is also enhanced, thereby increasing the locking range. In addition, the tripler adopted a fourth-order resonator, as a result, the phase of the resonant impedance is flattened at the zero-crossing point, then the locking range is further increased. The tripler is implemented in a standard CMOS 65nm process with a chip area of 720×670 um2, and the power consumption is 15.2 mW under a 1.2-V power supply. With 0 dBm power injection, the locking range is 19.2-27.6 GHz, and the corresponding fundamental suppression ratio is greater than 25 dB, and the second harmonic counterpart is beyond 35 dB. The proposed ILFT is capable of the requirements of the oscillation source in the 5G transceiver.
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Study on the multi-modes, multi-harmonics behavior of a THz large-orbit gyrotron
ZHAO Qi-Xiang, MA Meng-Shi, LI Xiang, LV You, ZHANG Tian-Zhong, Peng Lin, WANG E-Feng, FENG Jin-Jun
Abstract:
—The large-orbit gyrotrons (LOGs) in the THz range are attractive for the great potential of reducing the required external magnetic field by enabling the high-harmonics operation. In this paper, a LOG capable of operating from the 4th to the 9th harmonic is designed and investigated. With the assistance of the 3-D particle-in-cell simulation, the key features of the designed LOG, beam-wave interaction dynamics and high-harmonic operation regimes are studied. It is shown that by tuning the external magnetic field intensity, successive excitation of the oscillation at a number of neighboring harmonics can be achieved, corresponding to radiation frequencies between 240 GHz to 460 GHz with the maximum radiation power of 19 kW. Then, a detailed study of the competition among the 7th, 8th and 9th harmonics are conducted, providing an insight into the multi-modes, multi-harmonics behavior of the high-harmonic LOG. Following that, the methods to stabilize the beam-wave interaction and enable single mode operation at high harmonics are discussed. Additionally, the characterization of the ohmic loss power at different operation harmonics is conducted.
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Anisotropic tunable multi-order strong coupling in black phosphorous nanodisk-sheet plasmonic system
Abstract:
Black phosphorus supports anisotropic surface plasmons, which can be used to design principle devices with more functions. The hybridization behavior of different plasmon modes in the sheet-disk-sheet system based on black phosphorus in the mid-infrared to far-infrared waveband is numerically simulated by the finite-difference time-domain method. By dynamically adjusting the carrier concentration in the black phosphorus, the generation and control of the strong coupling phenomenon in the two lattice directions can be realized. Analyzing and calculating the coupling between different modes, the Rabi splitting energy in the absorption spectrum can be as high as 42.9 meV. In addition, the influence of the polarization angle on the strong anisotropic coupling is also calculated, which can achieve up to 6 absorption bands. The proposed model provides a basis for the construction of compact anisotropic plasmonic devices based on two-dimensional materials that will work in the mid-to-far infrared bands in the future.
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Nonlinearity correction of FY-3E HIRAS-II in pre-launch thermal vacuum calibration tests
YANG Tian-Hang, GU Ming-Jian, SHAO Chun-Yuan, WU Chun-Qiang, QI Cheng-Li, HU Xiu-Qing
Abstract:
The High-spectral Infrared Atmospheric Sounder II (HIRAS-II) is a Fourier transform spectrometer onboard the world’s first civil early-morning-orbiting FengYun 3E (FY-3E) meteorological satellite, the FY-3E/HIRAS-II focus on a number of upgrades such as the sensitivity of the detector, the accuracy of spectral calibration and radiometric calibration, with the designed and manufactured processing based on the first Chinese hyperspectral infrared (IR) sounder FY-3D/HIRAS-I. We conducted a comprehensive pre-launch thermal vacuum (TVAC) calibration tests for HIRAS-II, including the nonlinearity (NL) correction which consist an essential part of radiometric calibration, the NL correction has considerable effects on radiometric accuracy. According to the HIRAS-II nonlinear behavior of the detectors for long-wave (LW) and mid-wave (MW) infrared spectral bands, the NL correction of raw data in the spectral domain is a scaling of the observed spectrum, the NL correction coefficients are derived by the methods of minimizing the spread of the responsivity functions with varying temperature, or minimizing the spread of the bias of brightness temperature among calibration targets with varying temperature. The bias of spectral brightness temperature is assessed by comparing the NL correction and the non-NL correction radiometric calibration data, the results show that, the radiometric accuracy has been significantly improved via NL correction.
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Ka&W dual-frequency millimeter-wave cloud radar at Yangbajing ---Performance and comparison
Bi Yong-Heng, HUO Juan, LYU Daren, SU Tao, WANG Xue-rong, LIU Bo
Abstract:
This paper introduced a new dual-frequency millimeter-wave Doppler radar (YBJ-DFDR, W band 94 GHz, wavelength 3.2 mm, Ka-band 35 GHz, wavelength 8.6 mm) situated at Yangbajing in the Tibet Plateau and presented detailed analysis of the detection capability through calculations and comparisons. The analysis results show that the DFDR has a high sensitivity with -39.2 dBZ and -33 dBZ at 10 km for the W-band radar and Ka-band radar, respectively. It is shown that the radar equivalent reflectivity factor measured by Ka- and W- band radar illustrates various distribution characteristics for different cloud types. When rainfall occurs, W-band radar suffers much more attenuations by precipitation than the Ka-band radar (the difference between them reaches up to 30 dB in some cases), further, the attenuations may cause the loss of the reflectivity of W-band radar. On the other hand, when the cloud particles are mostly ice particles, the attenuation effect significantly decreased, and W-band radar shows stronger detection ability than the Ka-band radar with higher reflectivity values. In addition, it is also found that Ka-band radar is prone to miss more cloud edge areas than the W-band radar, such as the cloud top and cloud bottom area, resulting in underestimation of the cloud top height but overestimation of the cloud bottom height. The main reason is that the cloud particles in these areas are small and number concentration is generally low, which has weak reflectivity lower than the sensitivity of the Ka-band radar
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High birefringence hollow-core anti-resonant terahertz photonic crystal fiber with ultra-low loss
Abstract:
An ultra-low loss and high birefringence hollow core anti-resonant terahertz photonic crystal fiber based on cyclic olefin copolymer (COC) is proposed. The cladding of the fiber consists of two groups (six in total) nodeless embedded sleeves. The guided wave characteristics are analyzed by using the finite difference time domain method combined with the perfectly matched layer boundary conditions. The simulation results show that the total transmission loss is less than 0.1 dB/m, birefringence is more than 2.12 × 10-5 within the range of 0.8 THz - 1.35 THz, dispersion in ± 0.027 ps/THz/cm. At 1.12 THz, the minimum total transmission loss is only 0.543 × 10-2 dB/m, birefringence value 2.06 × 10-4. The bending performance of the fiber is analyzed. It is shown that in y direction, when the bending radius is more than 19 cm, the bending loss is less than 0.1 dB/m, and the bending performance is good.
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Analysis and verification of the positioning accuracy of a flat-panel detector used for precision pointing in space optical communication
WANG Xu, Tu Cheng-Xiang, ZHANG Liang, WANG Jian-Yu
Abstract:
To realize a high-precision link in space optical communication, we analyzed key factors that affect the accuracy of flat-panel detectors in terms of target positioning. The error of the centroid algorithm was analyzed from the mechanism and the necessity of satisfying the spatial lossless sampling condition was verified by using a simulation. The defined NU value served as an indicator in quantifying the nonuniformity of the detector. As the NU value increased linearly, the positioning error of the centroid continued to increase, whereas the speed reduced. When the NU value was 0.005, the maximum positioning error was 0.043 pixels. Considering that the light intensity of the target incident on the optical system varies constantly, the smaller the NU value, the closer the centroid is to the true position of the light spot. Furthermore, the pixel response of a typical complementary metal oxide semiconductor (CMOS) detector was experimentally tested under different illumination intensities. Based on the response curve, a mathematical model for the nonuniformity of the pixel response was established. It can be determined that the NU value fluctuates from 0.0045 to 0.0048 within the linear response range. The experimental results of the spot centroid positioning accuracy verify that the absolute positioning error is less than 0.05 pixels, which satisfies the requirements of high-precision links. Therefore, the effectiveness of the theory and simulation presented in this study can be validated.
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Retrieval of supercooled water in convective clouds over Nagqu of the Tibetan Plateau using Millimeter-wave radar measurements
Ren Tao, ZHENG Jia-Feng, LIU Li-Ping, ZOU Ming-Long, CHEN Shao-Jie, HE Jing-Shu, LI Jian-Jie
Abstract:
Abstract: Supercooled water in convective clouds has always been a difficult point in meteorological detection. In this paper, based on Doppler spectra of a Ka-band millimeter-wave radar used in the third Tibetan Plateau Atmospheric Experiment and relevant radiosonde data, an algorithm for identifying and retrieving supercooled water in convective clouds over Nagqu of the Tibetan Plateau was proposed. Subsequently, retrieval effects of the algorithm were analyzed using two convective cases (including stratocumulus, cumulus humilis, and altocumulus clouds), and verified by comparing with measurements from a co-located microwave radiometer (MWR). Finally, two useful empirical relations of effective radius–radar reflectivity (R_e–Z_e) and liquid water content–radar reflectivity (LWC–Z_e) for the supercooled water in convective clouds over Nagqu were presented. The main findings are as follows: The stratocumulus, cumulus congestus, and altocumulus clouds over Nagqu are dominated by updrafts with rapid changes on the hydrometeor phase in the vertical orientation, resulting widely distributions of the formed supercooled particles in terms of both their Z_e, R_e, and LWC. Supercooled particles in different convective cloud types also locate at different cloud body positions. The velocity of the in-cloud updraft is highly and positively correlated with the supercooled water Z_e, R_e, and LWC. They possess similar temporal variations and coincident spatial distributions. The retrieved spatial positions and microphysical parameters of the cloud supercooled water are consistent with the conclusions of previous studies and observations. The radar-derived LWP are also proved to agree well with the counterparts of MWR with similar temporal variations and value peaks. Their correlation coefficients can approach 0.63–0.79. For convective clouds of the Tibetan Plateau, R_e and Z_e of the supercooled water exhibit a confident power empirical relations, namely, R_e=195.4Z_e^1.78+8 for cloud droplets and R_e=67.8Z_e^0.3 for raindrops, respectively. Supercooled raindrops also possess a certain LWC–Z_e, that is LWC=0.024Z_e^0.82, whereas, the power-form relation for the cloud droplets is inapparent.
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Study on the improvement of scan mirror thermal radiation correction on the calibration accuracy of FY-4A AGRI
LI Xiu-Ju, WANG Bao-Yong, WU Ya-Peng, HAN Chang-Pei, CAO Qi, ZHOU Shu-Tian, WANG Wei-Cheng, LI Pan-Pan
Abstract:
The Advanced Geostationary Radiation Imager (AGRI) is one of the main payloads of Fengyun-4A (FY-4A). In order to satisfy requirements of high-precision quantitative application of AGRI long-wave infrared (LWIR) remote sensing data, the function model of scan mirror thermal radiation changing with mechanical rotation angle is constructed, and a correction algorithm for remote sensing data of on-board blackbody and earth scene observation is presented. Based on the on orbit data of FY-4A AGRI, the dependence of the model parameters on the scan mirror temperature is analyzed, and the improvement effect of the correction algorithm on the calibration accuracy of LWIR is studied and evaluated. In the stationary period of scan mirror temperature field, the calibration deviation of B11(8.0~9.0μm), B12(10.3~11.3μm), B13(11.5~12.5μm) can be improved significantly by -2.81K~+1.06K, -0.60K~+0.19K, -0.68K~+0.24K respectively. The result of cross calibration validation with IASI show that the improved on orbit calibration brightness temperature bias is better than 0.5K@290K.
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Research on p-on-n LWIR and VLWIR HgCdTe infrared focal plane detectors technology
LI Li-Hua, XIONG Bo-Jun, YANG Chao-Wei, LI Xiong-Jun, WAN Zhi-Yuan, ZHAO Peng, LIU Xiang-Yun
Abstract:
The p-on-n structure doped with As implantation has the advantages of low dark current,high R0A product, and long minority carrier lifetime,which is an important trend in the development of long-wavelength and very long-wavelength HgCdTe infrared focal plane detectors. P-on-n LWIR and VLWIR HgCdTe infrared focal plane detectors with cut-off wavelength of 9.5μm and 10.1μm at 77 K and 14.97 μm at 71 K fabricated by Kunming Institute of Physics are introduced.Test and analyze performance parameters such as the responsivity, NETD, dark current and R0A of the detectors. The test results show that the operable pixel factor of the detectors is between 99.78% and 99.9%,and the NETD of the detectors is less than 21 mK. The effective fabrication of p-on-n LWIR and VLWIR HgCdTe infrared focal plane detectors is realized.
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THz ISAR Imaging Using GPU-Accelerated Phase Compensated Back Projection Algorithm
LIANG Mei-Yan, ZHANG Cun-Lin, ALY E FATHY
Abstract:
Here, we present our implementation of two-dimensional (2D) high-resolution inverse synthetic aperture radar (ISAR) imaging using a 0.22 THz stepped-frequency (SF) radar system. The system is suitable for both near- and far-field imaging with a synthesis bandwidth of 12 GHz. The radar can provide highly accurate range and cross-range results in the near field, and its ISAR image can reach centimeter-level resolution upon using a phase-compensated Back-Projection algorithm (BP algorithm). These BP-realized results indicate that THz ISAR imaging can achieve both higher precision and finer resolution when compared to previously demonstrated range-doppler (RD) results with the same SFCW radar setup. To accelerate BP’s relatively slow image retrieval process, we employ accelerated platforms based on a graph-processing unit (GPU). Such success should pave the way for further research on near-field high-resolution radar imaging especially at THz/sub-millimeter bands.
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Graphene-embedded waveguide with improved modulation capability
Abstract:
We propose a graphene-embedded waveguide (GEW) with improved modulation capability, which can be over 2 times larger than that of conventional graphene-on-silicon (GOS) waveguide. More importantly, it is found that the improvement of modulation capability mainly results from the enhanced electric field confinement around graphene. Based on this finding, we propose a high-efficient method to optimize the modulation capability. By using this method, the optimization work can be reduced by an order of magnitude. Our work may promote the design of graphene-based electro-optic modulator with high modulation capability.
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A Distributed Small Signal Equivalent Circuit Modeling Method for InP HEMT
QI Jun-Jun, LYU Hong-Liang, CHENG Lin, Zhang Yu-Ming, ZHANG Yi-Men, ZHAO Feng-Guo, DUAN Lan-Yan
Abstract:
In this paper, a distributed small signal equivalent circuit modeling method for InP HEMT is presented. The distributed capacitance effect is taken into account in the adopted model, which is characterized by adding three distributed capacitances. For accurate modeling, considering the error caused by parasitic inductance when extracting parasitic capacitance, the parasitic inductance is extracted first. The validity of the proposed small signal modeling method has been verified with excellent agreement between the measured and modeled S-parameters up to 50GHz for InP HEMT. In addition, the proposed S-parameters fitting error is less than 4% in 2~50 GHz, which also proves the applicability of the proposed modeling methods for InP HEMT.
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Recent Progress on Natural Biomaterials Boosting High-Performance Perovskite Solar Cells
Shaobing Xiong, Qinye Bao, Junhao Chu
Abstract:
Perovskite solar cells (PeSCs) have been considered as one of the most promising photovoltaic technologies due to their high efficiency, low-cost and facile fabrication process. The power conversion efficiency and stability of PeSCs highly depend on the quality of perovskite film and the interfaces in the device, which are the main sources of PeSC nonradiative recombination losses. Natural biomaterials, with the advantages of earth-abundance, non-toxicity, and biocompatibility, have shown huge potential to improve both perovskite layer and interfaces in PeSCs. Herein, the latest progress using natural biomaterials to achieve high-performance PeSCs is reviewed. We firstly discuss the roles of natural biomaterials on perovskite film in terms of morphology optimization, defect passivation and energetics modification. Meanwhile, the strategies using natural biomaterials to create superior interface between perovskite and charge transport layer, and to build stretchable, biocompatible, and biodegradable electrodes are present. Finally, an outlook on the further development of PeSCs with respect to natural biomaterials is provided.
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Design of a novel Y-junction electro-optic modulator based on thin film lithium niobite
GuoHongjie, LIU Hai-Feng, WANG Zhen-Nuo, TAN Man-Qing, Lei Ming, LI Zhi-yong, GUO Wen-Tao, GUO Xiao-Feng
Abstract:
In recent years, the high-performance electro-optic modulator based on Thin-film lithium niobate (TFLN) platform has been receiving considerable attention due to the featuring small-footprint and low energy loss. In this paper, a novel Y-junction electro-optic modulator with a vertical electrode structure was designed based on TFLN. The relationship between the low half-wave voltage and the buffer layer thickness for the novel modulator was investigated. Meanwhile, the design parameters of Y-junction were optimized, and found that the half-wave voltage is less than 1.5 V and the insertion loss is less than 5 dB. Finally, the Y-junction electro-optic modulator was fabricated. This study not only provides insights on the design and realization of compact footprint photonic waveguides in TFLN platform, but also, experimental evidences for fabrication of electro-optic modulator with high-performance and multifunction.
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The band gap regulation of HgxCd1-xTe quantum dots by ion exchange and their near-infrared self-absorption characteristics
FANG Shi-yu, LIU Zhen-yu, JIN Jia-jie, SHI Ji-Chao, FANG Yong-zheng, SUN Chang-hong, YE Zhen-hua, LIU Yu-feng
Abstract:
The ion exchange is one of the important methods to realize the band gap regulation of alloy quantum dots. In this paper, monodispersed CdTe quantum dots are synthesized by soft chemical method. Meanwhile, mercury cadmium telluride (HgxCd1-xTe) quantum dots with the quasi continuous visible to near-infrared spectrum are prepared by ion exchange adjusting the concentration of Hg2+. The variable temperature photoluminescence and self-absorption characteristics of near-infrared Hg0.33Cd0.67Te quantum dots are deeply analyzed. The results indicate that the fluorescence intensity of HgxCd1-xTe quantum dots decreases linearly with the increase of temperature (0-100 ℃). The spectral line broad and the peak position has a red-shift (12nm). The partial overlap of absorption and emission spectra of quantum dots leads to self-absorption. The increase of self-absorption results in decrease of photoluminescence intensity while the concentration of quantum dots increases.
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Fast moving target detection algorithm based on LBP texture feature in complex background
QIU Li-Ya, CHEN Wei-Lin, LI Fan-Ming, LIU Shi-Jian, LI Zheng, TAN Chang
Abstract:
In the visible and infrared scenes with complex background, such as rain and snow weather, leaf swaying, shimmering water, etc., fast and accurate extraction of a complete target has always been the primary problem in moving target detection. In order to be real time and aiming at the problems of existing video foreground extraction algorithms, such as dependence on prior information, low recall rate, lack of texture and large noise, a background modeling method based on histogram statistics and improved LBP（Local Binary Pattern） texture features is proposed. Firstly, the mode of each pixel histogram is used as the reference background without prior knowledge, which saves a lot of storage space. Then, an improved S_MBLBP texture histogram is proposed to model the background with the reference background by using neighborhood compensation strategy, which eliminates most of the dynamic background and illumination changes, and realizes the accurate extraction of the target. Experimental results show that the proposed algorithm can quickly extract foreground targets in a variety of complex infrared and visible scenes, and can improve the accuracy and recall rate at the same time.
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Preparation of epi-ready InAs substrate surface for InAs/GaSb superlattice infrared detectors grown by MOCVD
LIU Li-Jie, ZHAO You-Wen, HUANG Yong, ZHAO Yu, WANG Jun, WANG Ying-Li, SHEN Gui-Ying, XIE Hui
Abstract:
Total reflection X-ray fluorescence spectroscopy (TXRF) and X-ray photoelectron spectroscopy (XPS) have been used to investigate residual impurities and oxides on polished InAs substrate surface wet cleaned by different solution combination. Metal impurities Si, K and Ca are routinely detected on the cleaned InAs surface and their concentration change with the variation of solution combination. A large quantity of particles (80nm size) are measured on the InAs substrate surface with higher residual impurity concentration. An effective wet chemical cleaning procedure is presented to prepare InAs substrate surface with less residual impurity, small particle quantity and thin oxide layer, which are beneficial to high quality epitaxial growth.
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Study on the Influence of Hg Vacancy Control of HgCdTe Materials with Different Passivation Layers through Thermal Annealing
Shen Chuan, Liu Yang-Rong, Sun Rui-Yun, Bu Shun-Dong, Chen Lu, He Li
Abstract:
The control of Hg vacancy concentration in HgCdTe grown by MBE with different passivation layer structures was studied. Higher Hg vacancy concentration in HgCdTe was obtained, which provides a basis for the subsequent research and development of new focal plane devices. It was found that the change of Hg vacancy concentration in HgCdTe varies with the structure of passivation layer during thermal annealing. The change is because the existence of the passivation layer of the HgCdTe surface layer changes the equilibrium process of the original thermal annealing. At the same time, the secondary ion mass spectrometry (SIMS) test and the corresponding theoretical fitting were verified the results.
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Research on summer Arctic cloud detection model based on FY-3D/MERSI-II infrared data
WANG Xi, LIU Jian, YANG Bing-Yun
Abstract:
Satellite is one of important observation data sources in Arctic. Due to the complex characteristics of atmospheric and underlying surface, it is extremely challenging for developing the cloud mask algorithm and the derived product accuracy in Arctic by satellite passive remote sensing. A summer cloud detection model in Arctic was studied based on FY-3D/MERSI-II (FengYun-3D/Medium Resolution Spectral Imager-II). Combined with the observations infrared cloud detection tests for the Arctic summer were proposed. The probability distribution density analysis method was adopted, and the loss rate was introduced to optimize the relevant thresholds. Meanwhile, the relevant thresholds were optimized to develop a cloud detection model based on the confidence levels. The validation results reveal that the cloud detection results are highly consistency with the matched CALIPSO observations. The high confidence levels basically represent the cloudy pixels, while the low values correspond to the clear ones. The case study shows that the ratio of cloudy pixels is 100% with confidence level higher than 0.8. When the confidence level is lower than 0.2, 10.15% of the cloudy pixels are still misjudged as clear pixels, which are primarily single-layer clouds with the cloud top heights between 4 and 6km. This may be caused Pby cirrus clouds and still need further study.
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Accuracy Estimation of Microwave Performance for InP HBTs based on Monte-Carlo Analysis
CAO Ke-Jing, ZHANG Ao, GAO Jian-Jun
Abstract:
In order to verify the reliability of the circuit, the microwave performance for InP HBTs is analyzed based on Monte-Carlo method. The larger the fluctuation range is, the higher the accuracy of extracting intrinsic parameters is required. The allowable accuracy range can be inferred from the output performance. The microwave characteristics are composed of modeled S-parameters, current gain cut-off frequency and maximum oscillation frequency. The standard deviation of Monte-Carlo numerical analysis can be derived from the uncertainty curve of the intrinsic parameters of the π-topology small signal model. The results of Monte-Carlo analysis show that the requirements for the accuracy of measurement parameters are quite different under different frequency and bias conditions, which verifies the reliability of the circuit under different conditions.
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A THz-TDS based Metamaterial Sensor for Sensitive Distinguishment of Food Additives
MA Jia-Lu, TANG Jing-Chao, WANG Kai-Cheng, GUO Liang-Hao, WANG Shao-Meng, GONG Yu-Bin
Abstract:
A sensitive terahertz (THz) metamaterial sensor for the distinguishment of common additives in the food industry is proposed. The metamaterial sensor consists of an array of split ring resonator (SRR) with double tip ends. By checking the resonate frequency shift of the sensor, the concentration and the type of the solution sample can be distinguished. The metamaterial sensor is fabricated on a quartz substrate, which is transparent for THz wave. The solutions with the concentration of 0.2, 0.4, 2 and 4mg/ml have been measured by using a terahertz time domain spectroscopy (THz-TDS). The results illustrate that the proposed metamaterial sensor can detect the concentration of the solution sample, as low as 0.2mg/ml. Meanwhile, different solutions with same concentration can also be clearly distinguished. Our study provides new insights for the application of terahertz metamaterial sensor based on SRR structure in the field of food safety.
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Interfacial properties between Al2O3 and In0.74Al0.26As epitaxial layer on MIS capacitors
WAN Lu-hong, SHAO Xiu-mei, LI Xue, GU Yi, MA Ying-jie, LI Tao
Abstract:
Metal-Insulator-Semiconductor (MIS) capacitors were fabricated on In0.74Al0.26As/In0.74Ga0.26As/InxAl1-xAs heterostructure multilayer semiconductor materials. SiNx and SiNx/Al2O3 bilayer were applied as insulating layer to prepare MIS capacitors respectively. High-resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscopy (XPS) measurements indicated that, compared with SiNx deposited by inductively coupled plasma chemical vapor deposition (ICPCVD), Al2O3 deposited by atomic layer deposition (ALD) can effectively suppresses In2O3 at the interface between Al2O3 and In0.74Al0.26As. According to the capacitance-voltage (C-V) measurement result of MIS capacitors, the fast interface state density (Dit) of SiNx/Al2O3/In0.74Al0.26As is one order of magnitude lower than that of SiNx/In0.74Al0.26As. The above results are calculated using the high-low frequency method. Therefore, it can be concluded that Al2O3 deposited by ALD as a passivation film can effectively reduce the interface state density between Al2O3 and In0.74Al0.26As, thereby reducing the dark current of p-In0.74Al0.26As/i-In0.76Ga0.24As/n-InxAl1-xAs photodiodes.
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Photonic crystal flat lens for polarization mode and light source insensitively
Liu Jian-Jun, CEN Yuan, XIE Jian-lan
Abstract:
The photonic crystal (PC) flat lens has broad application prospects in the field of super-resolution imaging and it has been researched deeply, but the lenses studied in the past are only suitable for specific polarization mode or specific incident light source. To this end, we propose a kind of PC flat lens with scatterer-size gradient. This flat lens can simultaneously realize point source imaging and plane wave focusing in TM and TE polarization modes, and break through the diffraction limit in TM polarization mode, and realize sub-wavelength imaging and focusing in TE polarization mode. This flat lens can realize polarization-insensitive imaging and focusing without any additional polarization components. It is expected to be used in the design of multi-functional optical polarization-insensitive imaging and focusing devices, and can be applied to real-time biological display, high-density optical storage and microelectronic lithography, and improve the application potential of gradient PC flat lens.
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Research progress of copper indium gallium selenide thin film solar cells
Abstract:
The industrialization of copper indium gallium selenide (CIGS) solar cells has attracted worldwide attention. As a thin film solar cell with high conversion efficiency, its efficiency can be compared with that of crystalline silicon solar cell, and the highest efficiency reaches 23.35% at present. For small-area laboratory solar cells, the main research focus is to accurately control the stoichiometric ratio and efficiency of absorption layer. For industrial production, besides stoichiometric ratio and efficiency, cost, reproducibility, output and process compatibility are very important in commercial production. The research progress of different preparation processes, gradient control of absorption layer composition, post-deposition treatment of alkali metal, wide band gap cadmium-free buffer layer, transparent conductive layer and flexible substrate were reviewed. From the perspective of the efficiency of CIGS solar cells, the transfer of record-breaking high-efficiency solar cell technology in the laboratory to the average industrial production level brings obvious challenges.
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Design and Test of a Low Voltage Suspended Dual-Microstrip Meander-Line Slow Wave Structure at Ka Band
HE Teng-Long, WANG Shao-Meng, LI Xin-Yi, XU Duo, SHI Ning-Jie, WANG He-Xin, GONG Hua-Rong, LU Zhi-Gang, WANG Zhan-Liang, DUAN Zhao-Yun, GONG Yu-Bin
Abstract:
A suspended dual- microstrip meander-line (SDMML) slow wave structure (SWS) is proposed in this paper. It consists of a metal enclosure as well as a suspended dielectric substrate, on the upper and lower surfaces of which are two metal meander-lines. As there are two electron beam tunnels locating above and below the dielectric substrate, and the electromagnetic wave has symmetrical distribution, it is possible to use one electron beam in each tunnel to drive the electromagnetic wave for a higher output power. The high frequency characteristics and the beam-wave interaction results of the SDMML SWS have been investigated by using simulation software. The hot performances of this SWS show that for two identical sheet beams with a voltage of 2050 V and a current of 0.2 A, the SDMML SWS has a maximum gain of 26 dB at 36 GHz and 3-dB bandwidth of saturation power of 8 GHz. To verify the simulation result, a SDMML SWS is fabricated by using new fabrication methods including the magnetron sputtering electroplate and laser ablation. The measured reflection loss of the SDMML SWS is better than -10 dB. The transmission loss of the fabricated slow wave structure is analyzed and verified through simulation and experimental results.
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Design and Realization of InP-based Resonant Tunneling Diode THz Oscillator
liujun, Song Ruiliang, Liu Ning, Liang Shixiong
Abstract:
Above 1 THz InP-based resonant tunneling diode (RTD) oscillator was designed and realization with Si-lens package. The RTD model was build and studied using Silvaco software including the influence of the doping concentration of emitter, the thickness of the barrier layer, space layer and well layer on the DC characteristics of the device. The DC measurement of the RTD shows peak current density Jp is 359.2 kA/cm2, valley current density Jv is 135.8 kA/cm2, peak-to-valley current ratio (PVCR) is 2.64, maximum RF output power of 1.71 mW and oscillation frequency (fmax) of 1.49 THz are theoretically calculated. The oscillator with an on-chip Bow-tie antenna has been packaged with Si-lens and the measurement shows the output power of 2.57 μW at an operation frequency of above 1 THz, the DC power consumption is 8.33 mW. This is the first reported oscillator of frequency above 1 THz in domestic.
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High performance Ge:B blocked impurity band detector developed by the near surface process technique
Pan Chang-Yi, Mou Hao, Yao Xiao-Mei, Hu Tao, Wang Yu, Wang Chao, Deng Hui-Yong, Dai Ning
Abstract:
Blocked impurity band (BIB) detectors are the start-of-art choice for far infrared astronomical observation. Ge:B BIB far infrared detector has been successfully developed using near surface process technique. The spectral response covers a wide range from 50 cm^(-1) to 400 cm^(-1). At 3.5 K and at 30 mV, the detector exhibits a highly competitive responsivity 21.46 A/W and a highly competitive detectivity of 4.34×10^14 cm?Hz1/2?W-1 at the peak response of 84.9 cm^(-1). We have studied the influence of the interfacial barriers on the spectral response. A new excitation model that the carriers in the contact regions can be excited over the interfacial barriers is proposed. A new method to enhance the relative response intensity of BIB detectors in the low wavenumber region is found.
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2001,20(3):184-188, DOI:
Abstract:
测量了几种不同处理的Cd1-xZnxTe(x=0.04)表面的傅里叶变换拉曼散射光谱和电流－电压（I－V）特性。通过分析拉曼光谱反Stokes分量，并与表面I－V特性进行比较，结果表明与表面处理相联系的晶格声子的行为反映了表面完整性的变化，Te沉淀是影响表面质量的关键因素，并对有关表面处理方法的实际应用进行了讨论。
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HU Zhi Gao WANG Gen Shui HUANG Zhi Ming CHU Jun Hao
2002,21(3):175-179, DOI:
Abstract:
采用溶胶－凝胶法在石英玻璃衬底上制备出均匀透明的无定形PbTiO3薄膜，并对其 光学性质进行了详细的研究，发现其折射率的波形符合经典的Cauchy函数。由半导体理论计算得到无定形的PbTiO3薄膜的光学禁带宽度为3．84eV.FTIR透射光 谱研究表明无定形PbTiO3薄膜在中红外波段没有吸收峰出现，对于在550℃下 快速热退火得到的PbTiO3薄膜，通过远红外反射光谱测量，观察到了6个约外活性声子膜。
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XU Yun, WANG Yi-Ming, WU Jing-Zhu, ZHANG Xiao-Chao
2010,29(1):53-56, DOI:
Abstract:
NIRS was used in rapid qualitative and quantitative detection for melamine of pure milk in this paper. Experiment was conducted by preparing two groups pure milk samples which melamine content is different for qualitative analysis and quantitative analysis. By combining NIRS technology with the cluster analysis method, A effective classification can be made on the two kinds of milk samples with and without melamine; To achieve this, spectrum pretreatment and wave length choice methods were employed before model optimization. The results showed that NIR models of predicting melamine content in pure milk has good stability and predictive ability.This paper suggested that NIR could be used as a quick, green and convenient method for predicting melamine content of dairy.
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CHENG Jian, ZHOU Yue, CAI Nian, YANG Jie
2006,25(2):113-117, DOI:
Abstract:
The particle filter is an effective technique for the state estimation in non-linear and non-Gaussian dynamic systems. A novel method for infrared object robust tracking based on particle filters was proposed. Under the theory framework of particle filters, the posterior distribution of the infrared object is approximated by a set of weighted samples, while infrared object tracking is implemented by the Bayesian propagation of the sample set. The state transition model is chosen as the simple second-order auto-regressive model, and the system noise variance is adaptively determined in infrared object tracking. Infrared objects are represented by the intensity distribution, which is defined by the kernel-based density estimation. By calculating the Bhattacharyya distance between the object reference distribution and the object sample distribution, the observation probability model is constructed. Experimental results show that our method is effective and steady.
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2010,29(1):69-74, DOI:
Abstract:
Image segmentation is one of the difficult problems in computer vision research. Recently spectral clustering has a wide application in pattern recognition and image segmentation. Compared with traditional clustering methods, it can cluster samples in any form feature space and has a global optimal solution. Originating from the equivalence between the spectral clustering and weighted kernel K-means, the authors proposed a spectral clustering algorithm with spatial constraints based on the spatially coherent property of images, also named continuous property. The spatially coherent property means that pixels in the neighbor region should share the same label assignment with the centre one with a high probability. The algorithm adds a term of spatial constraints to the objective function of weighted kernel K-means and makes the minimization of the objective function be equivalent to the spectral clustering through approximation. Experimental results show that our proposed algorithm outperforms the traditional spectral clustering in image segmentation.
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2010,29(1):63-68, DOI:
Abstract:
A novel infrared target extraction algorithm based on particle swarm optimization particle filter(PSOPF) was proposed. The problem of infrared target extraction was analyzed and solved in the view of state estimation. In the framework of particle filter, the threshold state space on the gray-variance weighted information entropy and the grey value of each pixel was based on extraction results evaluation function, which integrated grey, entropy, gradient and spatial distribution of pixels. Finally, the weighted average of all the particles was used as target extraction threshold. The experiment results prove that the proposed algorithm is effective and robust.
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EFFECTS OF APODIZATION FUNCTIONS OF IMAGING FOURIER TRANSFORM SPECTROMETER ON RECONSTRUCTED SPECTRUM
ZHANG Wen-Juan, ZHANG Bing, ZHANG Xi, GAO Lian-Ru, ZHANG Wei
2008,27(3):227-233, DOI:
Abstract:
随着搭载干涉成像光谱仪HJY20-1-A的我国环境与减灾遥感卫星HJ-1A即将发射,我国干涉光谱成像研究也从实验室开始走向实用化.在干涉光谱成像过程中,切趾函数处理是干涉成像光谱仪光谱复原过程中的一个重要环节,对复原光谱的精度有着极其重要的影响.根据HJY20-1-A的参数设置,文中首先模拟了24种典型地物对应于HJY20-1-A和其它最大光程差设置的干涉成像光谱仪数据,在不同切趾函数作用下的复原光谱,结果表明Hanning函数是其中最有效、最为稳定的切趾函数,同时发现切趾函数的应用虽然可以提高复原光谱的精度,但与真实光谱仍存在一定差距,尤其对应HJY20-1-A,复原光谱的精度更加有限.在以上分析基础上,提出了基于仪器线型函数标准化的光谱复原改进算法,实验结果证实了该方法可以显著提高复原光谱精度,尤其适用于最大光程差较小的空间调制型干涉成像光谱仪.最后,就HJY20-1-A复原光谱对3种典型植被指数求解,进一步证明了该方法的有效性.
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2008,27(2):123-128, DOI:
Abstract:
多数传统分类算法应用于高光谱分类都存在运算速度慢、精度比较低和难以收敛等问题.本文从支持向量机基本理论出发建立了一个基于支持向量机的高光谱分类器,并用国产OMIS传感器获得的北京中关村地区高光谱遥感数据进行试验,分析比较了各种SVM核函数进行高光谱分类的精度,以及网格搜寻的方法来确定C和愕闹?结果表明SVM进行高光谱分类时候径向基核函数的分类精度最高,是分类的首选.并且与神经网络径向基分类算法以及常用的最小距离分类算法进行比较,分类的精度远远高于SVM分类算法进行分类的结果.SVM方法在高光谱遥感分类领域能得到广泛的应用.
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SUN Jun-Ding, DING Zhen-Guo, ZHOU Li-Hua
2005,24(2):135-139, DOI:
Abstract:
A new image retrieval algorithm based on image entropy and spatial distribution entropy was presented. At first a more robust method, which can remove the influence of the symmetry of entropy, was proposed to extract the global color feature. Then color spatial distribution entropy vector for each color channel was also introduced to represent the spatial color information. After that, the moments were adopted to reduce the dimension of color spatial distribution entropy. In the end, a low dimensional vector which includes the global and spatial information was used as index for color image retrieval. The experiment results show that the new method gives better performance than color histogram.
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ZHANG Yu-Hong, CHEN Zhan-Guo, JIA Gang, SHI Bao, REN Ce, LIU Xiu-Huan, WU Wen-Qing
2008,27(3):165-169, DOI:
Abstract:
首次测量了硅材料在1.3μm波长处,基于克尔效应和弗朗兹-凯尔迪什效应的电致双折射,进而计算出三阶非线性极化率张量X(3)的分量X(3)xyxy.观测到弗朗兹-凯尔迪什效应引起的折射率变化与入射光的偏振态有关.在实验中,测得了由克尔效应引起的折射率之差为⊿n=5.49×10-16E20,而弗朗兹-凯尔迪什效应引起的折射率之差为⊿n'=2.42×10-16E2.50.
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WU Xiang, PEI Zhi-Bin, QU Shao-Bo, XU Zhuo, ZHANG Jie-Qiu, MA Hua, WANG Jia-Fu, WANG Xin-Hua, ZHOU Hang
2011,30(5):469-474, DOI:
Abstract:
By adjusting the effective permittivity of the unit cell, a new method of constructing metamaterial band-pass frequency selective surface was proposed. The effective permittivity of continuous conducting wires is negative below the plasma frequency and thus a stop-band occurs. By combining the continuous conducting wires with cut wires, we realized a one-dimensional frequency selective surface. Both the theory analysis and simulation results demonstrated the facility and feasibility of the method. We also designed a wide-angle and polarization-independent frequency selective surface based on this method. Two samples were fabricated to validate the proposed method; the experiment results were fairly consistent with the simulation results. The proposed method eliminates the complicated calculation and excessive parameter optimization process. It paves a new way of designing frequency selective surfaces and is of important reference values for fabricating THz frequency selective surface as well as multi-band, tunable and miniaturized frequency selective surfaces.
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LI Jie, ZHAO Chun-Hui, MEI Feng
2010,29(2):150-151, DOI:
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.
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2011,30(5):412-414, DOI:
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.
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WANG Nan-Nan, QIU Jing-Hui, ZHANG Peng-Yu, DENG Wei-Bo
2011,30(5):419-424, DOI:
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.
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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:
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．
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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:
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.
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WU Gang, LI Chun-Lai, LIU Yin-Nian, DAI Ning, WANG Jian-Yu
2007,26(3):213-216221, DOI:
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.
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WANG Huai-Ye, ZHANG Ke, LI Yan-Jun
2005,24(2):109-113, DOI:
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．
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2007,26(1):65-68, DOI:
Abstract:
A method for designing and training artificial neural network based on genetic algorithm(NNDT) was presented.NNDT trains both architectures and weights of networks simultaneously.The problem that the one-to-one relationship between the topology and the encoding can not be kept was solved effectively.Heuristic method was used to constraint the probability of topology mutation and the trend of the choice of the kind of mutation.Also,the niching mechanism was used to protect the mutation of network topologies.The experiments results show the efficiency and rapidity of NNDT.
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WANG Hui, ZHAO Feng-Jun, DENG Yun-Kai
2015,34(4):452-459, DOI: 10.11972/j.issn.1001-9014.2015.04.013
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.
