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.

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.

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.

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.

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 InAs_0.66Sb_0.34 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/InAs_0.66Sb_0.34 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.