Abstract:A specific digital output research on short-wave infrared InGaAs linear focal plane array (FPA) was reported. Coupled with a laboratory self-designed short-wave infrared 256×1 InGaAs FPA, a successive approximation register (SAR) analog to digital convertor (ADC) with high resolution, low power consumption and small size was designed and fabricated in 0.18 μm CMOS process. The chip consumes 460 μW at a sampling rate of 235 KS/s with the power supply of 3.3 V. The signal to noise ratio (SNR) of the ADC chip is 66.6 dB. The ADC chip was also tested at different integral time to convert the 256×1 InGaAs FPA signal. The results show that the ADC chip can meet the application requirements of the 256×1 InGaAs FPA.

Abstract:This paper proposed a readout integrated circuit ( ROIC) with high uniformity and low-noise, by mitigating the fixed patter noise ( FPN) of Infrared focal plane arrays ( IFPA) to acquire high-quality infrared images.The row shared gain-controlling NMOS transistors are adopted in front-end circuit to reduce the pixel FPN. Furthermore, a novel correlated double sampling ( CDS) structure is proposed to reduce the column FPN. Based on the simulation results, a 16 × 16 experimental chip has been manufactured adopting AMS 0. 35 μm CMOS process.Extensive experiments have been implemented to verify the function and performance of the proposed readout circuit.The test results demonstrate the ROIC with the inherent advantages of low FPN and high uniformity, which makes it suitable for the application of high performance IFPA.

Abstract:A folded microstrip meander line ( FMML) slow-wave structure ( SWS) based on slotted dielectric substrate is proposed. Due to the metal meander line printed in a semi-circular slot of the dielectric substrate, the proposed FMML SWS is very suitable for traveling-wave tubes ( TWT) with cylindrical electron beam ( CEB) , which can be focused by a traditional periodic permanent ( PPM) magnetic focusing system. The analyses of dispersion characteristics, coupling impedances, transmission properties and particle-in-cell ( PIC) of the proposed FMML SWS are investigated. Compared with traditional planar microstrip meander line ( PMML) SWS, the FMML SWS has the advantages of lower phase velocities, weaker dispersion and higher coupling impedances, which make the FMML SWS suitable for developing low-voltage, wideband and miniature millimeter-wave TWTs. With a focus magnetic of only 0. 4 T, a Ka band TWT with the FMML SWS is capable of delivering 42. 32 W output power with a corresponding gain of 26. 26 dB at 35 GHz, while the voltage and the current of the electron beam are set to be 6 550 V and 0. 1 A, respectively.

Abstract:Thermal and deformation analysis of W-band gyrotron traveling wave tube amplifier ( Gyro-TWTA) gun are carried out by using the finite element code ANSYS in the paper. Temperature distribution and thermal deformation of the cathode component at given heater power are simulated. These results are verified experimentally in an electron gun. The measured temperature distribution is in agreement with the simulation prediction.Finally, the electron trajectories with and without considering deformation are simulated by EGUN code.

Abstract:Recent years, shortwave infrared ( SWIR) imaging system has been developed rapidly, and additional active lighting is very necessary in some scenarios. At present, the uniformities of laser illumination homogenization schemes commonly used are not high, and can't reach the requirements of imaging. A new 25 × zoom laser illumination system was designed based on the analysis of the laser model in fiber and the theory of zoom illumination system. The optical lens of the illumination system is composed of three groups of lenses, and the CAM structure achieves continuous zooming. This system is small in size, has simple structure, and gains large zoom ratio.Finally a continuous change of 2 ～ 50° in illumination angle is achieved. Laser illumination intensity uniformity reaches 92. 7%. In the imaging experiments, the human identify distance was up to 1. 2 km. The continuous zoom laser illumination system is of high significant for improving the ability of the short-wave infrared night vision system.

Abstract:An efficient method for a coupled microsphere and waveguide system is proposed and demonstrated numerically and experimentally. In order to study the coupling characteristics of the microsphere-waveguide system, a two-dimensional ( 2D) model is exploited by the coupled theory firstly. A numerical simulation system is designed with the finite difference time domain ( FDTD) method. The relative intensity spectra and transmission spectra in the wavelength range from 600 nm to 1000 nm are acquired by processing the sample data after fast fourier transformation ( FFT) . In the experiment, the quartz-microsphere is fabricated by melting the tip of a single-mode optical fiber. The tapered fiber, fabricated by using the heat-and-pull technique, is chosen as a waveguide to excite whispering gallery modes ( WGMs) of the microsphere. The microsphere-taper coupling system is tested and the results indicate that a very high quality ( Q) factor up to 2. 3 × 106 and a high coupling efficiency up to 92. 5% can be achieved by optimizing the microsphere position and orientation relative to the tapered fiber. These coupling characteristics can be well explained with the theoretical results. Such properties show its great potential in practical microcavity sensing and micro-lasers.

Abstract:After removing the Hg1-xCdxTe infrared focal plane device substrate, the response bandwidth can be extended to the visible light band, which can significantly reduce the size and weight of the system in the application of hyperspectral imaging, and miniaturize the photoelectric detection system.Miniaturization has important practical value. The determination of the optical constants of HgCdTe materials in the visible near-infrared region is of great significance for the performance of HgCdTe devices in this response band. The ellipsometric spectra of different compositions of HgCdTe materials were measured and their optical constants in the band from 400 to 1 600 nm were fitted. The obtained optical constants were verified by using the reflectance spectra. Using these measured values, and using ZnS and YF3 as the high and low refractive index anti-reflective coating materials respectively, HgCdTe focal plane devices responding to different widths of back-incident near-infrared light have been designed.Spectroscopic AR coatings have an average transmission rate in the range of the response band of more than 90%.

Abstract:A denoised and wide swath thermal imaging technology based on low rank matrix approximation ( LRMA) was proposed to solve the problem of low signal-to-noise ratio ( SNR) of thermal imaging system noise in strong background and weak signal scene. This technology utilized array whisk broom mode to realize wide swath imaging and construct strict observations. The denoising low-rank matrix of observations was solved via weighted nuclear norm minimization ( WNNM) . Experiments showed that the technology had high peak signal to noise ratio ( PSNR) and denoising robustness. Both of imaging width and detection sensitivity were improved. The technology has certain application value in the field of weak target recognition and large area investigation.

Abstract:In this paper, a new NIR polarization detector is presented. It is fabricated out of a wire grid polarizer attaching to the surface of a FPA. A brand new method solving linear polarization is proposed at the same time. The transmittance and the angle of the wire grid are corrected. The effect on the degree of linear polarization ( DoLP) measurement is also eliminated in this report. Theoretically, the infrared polarized image quality is independent of the transmittance and angle of wire grid. The experiment uses a blackbody source as the calibration light. The results show that, while ignoring the crosstalk between the polarized pixels, the measured value is about 14% ～ 24% of the true value. After adding the transmittance correction, the data reaches the level of 80% ～ 120% while it becomes 96%to 104% by applying the angle correction.

Abstract:The study of terahertz radar scattering characteristics is important for target identification, tracking, and interception. A 0. 22 THz stepped-frequency Radar Cross Section ( RCS) measurement system is designed, and the RCS extraction method is also proposed. Using the combination of experiments and simulations, the terahertz radar cross section of a single corner reflector and corner reflector group within 4° is obtained. The results show that the RCS experimental results and the theoretical calculation results of the corner reflector target are in good agreement within the error range, which lays the foundation for further accurate measurement of the scattering characteristics of the target in the THz band.

Abstract:The scale problem is the main challenge of Earth observation, and it is also the core issue that has been receiving attention in remote sensing science. A lot of basic theoretical research and scientific verification work have been done on this, and many core issues related to remote sensing standards have been discussed and solved. In remote sensing content, scaling issues including emissivity and temperature measurements are more reliable and less affected by the Earth's atmosphere. At the same time, with the continuous update of the Diviner thermal radiation detector's monthly surface measurement data, the specific research and quantitative description of emissivity scaling problems in mixed pixels has gradually become possible. Based on Diviner's thermal infrared measurement data on the moon's surface, the thermal infrared emissivity of the moon landing area or moon landing point of Apollo15 at different scales was studied under the premise of full study and analysis of Diviner data characteristics and emissivity calculation methods. Based on the definition of mixed-cell emissivity, two problems of emissivity scaling and scale effect in mixed pixels are analyzed and studied. From the emissivity numerical point of view, the general rules of scaling and scaling effects are discussed and verified.The given quantitative descriptions are hoped to provide theoretical support and experimental evidence for research on issues such as scale transformation and scale effects.

Abstract:In order to study the causes and characteristics of indium bump defects in infrared focal plane arrays ( IRFPA) , during the fabrication of InSb IRFPAs, indium bumps of different pixel sizes were studied using positive photoresist. Then, the surface morphology of the chip, the connectivity of the detector, and the performance of the detector were characterized using an optical microscope and an FPA test stand, respectively. The results show that the chip surface and detector connectivity of the 50μm × 50 μm pixel size sample is better than other chips. Due to the small pixel size, the surface topography of the chip is connected or missing to the defective indium bump. The connectivity test results are consistent with the test results of the indium raised surface topography. The connected defects are due to the surface of the indium bumps caused by indium remnants during lithography and stripping.The missing defects are due to the lack of elemental indium bumps caused by positive photoresist residual during photolithography. The response voltage of the connected faulty component is basically the same as the response voltage of the normal component. The response voltage of the defect defective element is zero, and the response voltage of the nearest neighbor element is increased by about 25%compared with the normal element. The result has important reference significance for improving the performance of the FPA detectors by optimizing the production process.

Abstract:A novel short infrared multichannel integrated spectrum assembly ( MISA) worked in the range of 1 355 ～ 1 555 nm is reported. The influence of the incident angle on the center wavelength of each channel and the resolution of MISA is quantitatively studied in a theoretical and experimental manner.The experimental results show that the center wavelength of each channel of the spectroscopy component exhibits different degrees of short-wave direction shifting at 0 ～ 10° oblique incidence, and the degree of deviation is positively correlated with the incident angle. The theoretical and experimental center wavelength offset curves are plotted, and the experimental results show that the average shift amplitudes of the center wavelength at the incident angles of 5° and 10° are approximately 5. 7 nm and18. 67 nm, respectively. In addition, by referring to the experimental angle deviation curve, the spectrum was interpolated and integrated at two different incident angles, and the resolution of the spectral components was successfully increased from 7. 5 nm to 3 nm. Based on this experiment, we proposed a multi-channel angular tuning spectral assembly by changing the incident angle, and then using this method to improve the test resolution of the spectral components. This conclusion has certain guiding significance for designing the incident optical system and improving the test resolution of MISA.

Abstract:A broadband 360 ～ 440 GHz subharmonic mixer based on Schottky diode designed by UESTC and fabricated by CETC-13 is presented. Diode modeling is described to simulate the electromagnetic environment due to geometry-dependent parasitic effects in the extremely high frequency band. The whole subharmonic mixer is optimized by means of combination of field and circuit in HFSS and ADS.Measured results show that the sub-harmonic mixer yields minimum conversion loss of 9. 99 dB at 406 GHz, while the conversion loss was less than 15 dB over 380 GHz to 430 GHz and less than 19 dB over360 GHz to 440 GHz when LO power was 6 dBm at 210 GHz.

Abstract:Organic-inorganic hybrid perovskite solar cells are considered as one of the most promising third-generation photovoltaic technologies. After only a few years of research, the highest efficiency of perovskite solar cells has exceeded 22%. As the efficiency of perovskite solar cells has become closer to theoretical efficiency, researchers have turned their attention to the near-infrared bands that perovskite materials cannot effectively absorb, in order to further increase the efficiency. In this article, we review the research of combining up-conversion materials with perovskite solar cells in the past two years and classify them into more traditional methods and new methods. The traditional method is to use a relatively single NYF nanoparticle to dope the perovskite solar cell, utilize the up-conversion effect of rare earth ions, absorb the near infrared light, widen the absorption range of the perovskite, and thus enhance the performance of the solar cell. The new method is to add other ions or introduce heavily doped semiconductor materials to further enhance the performance of solar cells based on the traditional single use of rare earth ions. From the experimental results, both methods have achieved better performaces.

Abstract:The fast radiative transmission model can quickly calculate the transmittances coefficients by extending a series of optical depth core functions and channel spectral characteristics, so as to obtain an accuracy that is compatible with the line-by-line model. In this paper, four fast forward operators are established to predict the optical depth ( OD) of mixed gas, water vapor line absorption and water vapor continuum absorption of RTTOV v7, v8, v9 and CRTM v2. 1 in 6 infrared channels of AGRI in FY-4. The largest STDs of all the four fast operators are less than 0. 6 K in brightness temperature of AGRI. The STD of water vapor, CO2 and channel transmittances simulation in RTTOV v9 are the smallest among the four models. And the errors are less in lower levels than that of higher levels in the channel transmittances simulation. Experiments were also conducted using standard atmospheric profiles to calculate the Jacobine and OD of the mixed gas, water vapor absorption and water vapor continuum absorption. The OD errors of the mixed gas decrease with the new information of the deviations of real atmosphere profiles and the reference ones in v9. Simulations of OD of water vapor are improved by 19 water vapor line absorption profiles and 4 water vapor continuum absorption ones in v9.

Abstract:Soil water is an important component of the global ecosystem. Quantitative remote sensing estimation of soil water content in Karst Rocky Desertification Area can provide basic data and theoretical support for rocky desertification control and ecological restoration. It also provides guidance for agricultural activities in Rocky Desertification Areas. Based on Sentinel-1 A and Landsat 8 image data, the backscatter coefficients of shrub land and sparse woodland were extracted by using water cloud model, and TVDI of dry land and forest land were calculated by simplified Ts/NDVI feature space. Combined with the measured data, the soil moisture content of different depths was modeled by fitting analysis, which was used to inverse the soil moisture content. The results show that the VH polarization quadratic curve model and the VH polarization cubic curve model are suitable for inversion of soil water content at depths of 0 ～ 5 cm and 5 ～ 10 cm in shrub lands, respectively. The R2 and RMSE of the two models were 0. 87, 0. 87 and 4. 57%, 4. 29% individually. The exponential regression model of VH polarization was applied to soil moisture inversion of sparse woodland in 0 ～ 5 cm depth and the linear regression model of VH polarization was suitable for 5 ～ 10 cm depth. The R2 and RMSE of the two models are 0. 736, 0. 72 and 9. 77%, 11. 28% respectively. The best soil moisture inversion models of dry land and forested land are the cubic curve model and the logistic regression model respectively.And the R2 and RMSE of 0 ～ 5 cm depth soil moisture inversion are 0. 85, 0. 69 and 2. 88%, 4. 02%, while in 5 ～ 10 cm depth the value of R2 and RMSE are 0. 76, 0. 23 and 3. 5%, 6. 37% individually.

Abstract:A Generalized Multi-Bernoulli Filter for Track-before-detect ( GMB-TBD) of objects from image observations when the objects' influence region overlapping is proposed. The overlapping objects' measurement likelihood function is analyzed, the likelihood function is estimated by predicted objects' states, and then objects' overlapping influence is eliminated on objects' states updating by using this estimation. In this filter, the predicted and updated objects' states are strictly assumed as Multi-Bernoulli RFS, so it's a true Multi-Bernoulli based TBD filter and it can be used under both the objects' influence region overlapping and non-overlapping situations. The filter's realization steps are given. Objects' tracks are pruned and extracted by labeling Multi-Bernoulli components. Lastly, GMB-TBD filter's performance is verified by computer Monte-Carlo simulation results.

Abstract:The laser ranging systems based on SNSPD and SPAD detectors are compared by experiments.In the experiments, the sky light background can be ignored when the receive echo is attenuated to 120 dB, the detection probability of SPAD is less than 0. 2%, while the detection probability of SNSPD is 35%. When the laser emission frequency is below 1 kHz, the detection probability of SNSPD is more than 60% higher than that of SPAD. The study shows that the detection performance of SNSPD is much better than that of SPAD when detecting the weak signal echo photons. The reason is that SNSPD has lower dark counts and higher detection probability. At the same time, with no attenuation at the receiving end, the sky light background will bring dark counts, affecting the signal-tonoise ratio of the ranging system. Simulation analysis shows that the signal-to-noise ratio of the SNSPD-based laser ranging system is lower than 6 when the background luminance is higher than 30 W/ ( m2·sr) , which may affect the stability detection of the laser ranging system.