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 PeSCs 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. It’s discussed 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 a superior interface between the 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.

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 9.5 μm 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 operability 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.

Abstract:We design and fabricate a double-wavelength tunable laser with a single grating structure using a single-gain chip. The gain chip adopts an indium-rich cluster quantum constraint structure， which can generate ultra-wide flat-top gain. The flat-top gain is the basis for producing a dual-wavelength laser with the same intensity. A grating is inserted into the exterior of the gain chip so that its resonator is composed of internal and external cavities. The internal cavity consists of two natural cleavage planes of the gain chip for oscillating the output laser at a fixed wavelength （974 nm）. The tunable external cavity consists of a natural cleavage plane and a grating for the output laser at a tunable wavelength （969.1~977.9 nm）. The laser structures of the single-gain chip and single grating can produce synchronous dual-wavelength output， which avoids a complicated optical path design. The frequency difference between the two wavelengths is in the terahertz band. Thus， the laser can be used as a dual-wavelength laser source to generate terahertz radiation.

Abstract:Superlattice materials have become the preferred materials for the third-generation infrared focal plane detectors. The dual-band infrared detector can suppress the complex background and improve the detection effect by comparing the spectral information difference in the two bands， which is particularly important in demand. In this paper， it reports research results of 320 × 256 dual-color mid-mid-wavelength infrared InAs /InAsSb superlattice focal plane arrays. The detector structure is NBN epitaxial multilayer and the signal is read out by sequential mode. The pixel center distance from the detector is 30 μm. At 77 K measurement， the SMW detector has a peak detectivity of 7.2×10¹¹ cm·Hz^1/2W^-1 and dead pixels rate of 0.49%. The MW detector has a peak detectivity of 6.7×10¹¹ cm·Hz^1/2W^-1and dead pixels rate of 0.87%. Infrared images of both wavebands have been taken well-infrared imaging test by adjusting devices voltage bias．

Abstract:We demonstrate a room-temperature sub-terahertz photoconductive detector based on graphite nanosheet （GN） using electromagnetic induced well （EIW） effect produced in the metal-GN-metal structure. The detector achieves high performance of room-temperature THz detection. It shows a responsivity of over 20 kV/W at 0.035 THz and 11 kV/W at 0.1673 THz， as well as NEP of about 1.25 pW/Hz^1/2 at 0.035 THz and 2.27 pW/Hz^1/2 at 0.1673 THz， respectively. The results open up a new idea for graphene-based THz detection.

Abstract:A high efficiency Denisov-type quasi-optical mode converter for a 170 GHzmode 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 mode and the mode conversion efficiency of a quasi-optical mode converter is 93.7%.

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 0.8-1.35 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.

Abstract:The article proposes a wideband injection-locked frequency tripler （ILFT）. 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 65-nm process with a chip area of 720×670 μm²， 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， 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 of the 5G transceiver.

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 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， 1.5， 2， 3 and 4 mg/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 0.2 mg/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.

Abstract:A spectral analysis algorithm based on the combination of Hilbert transform （HT） 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 （MUSIC） spectrum estimation and auto regressive （AR） 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.

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 consists 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-wave1 （MW1） 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 of reconstructed spectrum in each wavenumber 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.

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-accuracy quantitative application of AGRI long-wave infrared （LWIR） remote sensing data， a 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. After thermal radiation correction of scan mirror in the stationary period of mirror temperature field， the calibration deviation of B11（8.0~9.0 μm）， B12（10.3~11.3 μm）， B13（11.5~12.5 μm） can be improved significantly by -2.81 K~+1.06 K， -0.60 K~+0.19 K， -0.68 K~+0.24 K respectively. The result of inter-calibration validation with IASI shows that the improved on-orbit calibration brightness temperature bias is better than 0.5 K@290 K.

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 about 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 achieve 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 on sea surface object detection. The proposed method has great application potential for on-orbit ship detection.

Abstract:In recent years， the high-performance electro-optic modulator based on the 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 the TFLN platform but also， experimental evidence for the fabrication of electro-optic modulators with high-performance and multifunction.

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.

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 the most 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.

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.