Abstract:This paper presents a transmitter-type TMIC integrated with a rectangular microstrip patch antenna and a power amplifier. The TMIC was fabricated with GaN HEMT technology for high power density and efficient integration. The on-chip antenna was designed as a power radiator and a frequency-dependent output load tuner of the power amplifier. Load-pull technique was used to realize a good impedance match between the amplifier and the antenna. Over a bandwidth of 100~110 GHz, the power amplifier can deliver an average output of 25.2 dBm with a power-added efficiency （PAE） of 5.83%. Good radiation characteristics of the TMIC have been achieved, showing a 10-dB bandwidth of 1.5 GHz and an estimated equivalent isotropic radiated power （EIRP） of 25.5 dBm at 109 GHz.

Abstract:The improved transmission and mirror system for a 263 GHz DNP-NMR spectrometer has been designed and numerically simulated based on the geometric optics theory and the vector diffraction theory. The system includes two corrugated waveguides, a parabolic mirror and an angle-adjustable phase-correcting mirror. The simulation results show that a well-focused Gaussian-like output wave-beam with 99.90% scalar Gaussian mode content, 99.55% vector Gaussian mode content has been obtained. The direction of the output beam can be changed by only adjusting the angle of the phase-correcting mirror to match the DNP-NMR sample. The scalar Gaussian mode content is about 99.57%, and the vector Gaussian mode content is about 98.97% when the direction of the output beam changes in ± 15^o.

Abstract:For pre-research on ice cloud detection equipment, the design and test of a low conversion loss （CL） 4^th-harmonic mixer working at the central frequency of 670 GHz based on an anti-parallel Schottky diode are presented. In order to improve the mixing efficiency, a two-stage local-oscillator （LO） compact-microstrip-resonate-cell （CMRC） low-pass-filter （LPF） is utilized to suppress the second mixing item （）, the third harmonic of LO signal（）, and RF signal. The LO frequency is only one-quarter of the RF frequency which significantly reduces the complexity and cost of the LO chain. The measurement result shows that the Single-Side-Band （SSB） conversion loss is between 16.7 dB to 22.1 dB from 640 GHz to 700 GHz at room temperature. The minimum conversion loss is 16.8 dB at the RF frequency of 665 GHz.

Abstract:To make the pulse couple balanced, an asymmetric Mach-Zehnder interferometer (AMZI) with a tunable directional coupler (DC) of a silica-based planar lightwave circuit (PLC) technology was proposed. The simulation results show that the DC tuning effect is better when the refractive index of both coupling arms changes independently. When the distance between the electrode and the waveguide core in the coupling zone is 0, the temperature difference between the coupling arms reaches the maximum. The test results of AMZI show that the insertion loss is 2.05 dB and the delay time is 151.4 ps. The power ratio of the pulse couple is highly close to one. Our device presents a practical solution to improve the performance of future integrated QKD device.

Abstract:Inter-satellite laser links have the advantages of high data rate, long transmission distance and low probability of detection/intercept. It has become an important trend in satellite technology. The inter-satellite point-to-point laser links are high mobility, and have narrow beam width, which bring challenges to the PAT processes. Due to their high computational complexity and large delay, the existing free space networks （FSO）topology control strategies cannot be directly applied to satellite networks. In this article, an algebraic connectivity based network dynamic topology control scheme is proposed. With distributed construction and enhancement process, the network dynamic reconfiguration is accomplished. A modified edge perturbation method is developed, and proved to have lower computational complexity than existing methods. The scheme is distributed, self-organized and near real-time, it which meets the requirements of dynamic topology control well and will contribute to building operationally responsive space （ORS） satellite networks.

Abstract:In this paper, a design of compact array which can excite anti-symmetric mode on special frequency selective surfaces is introduced. Based on compact cross-shaped array, we proposed an angle independent broadband terahertz （THz） bandstop filter with compact cross-shaped array. The compact cross-shaped array is composed of two layers of cross-shaped metal array, in which the center of every cross-shaped unit cell in second layer is arranged at the center of four cross-shaped unit cells in the first layer. Numerical results demonstrate that the compact array can efficiently increase the received area of the filter and excite an additional resonant mode. Compared with traditional repetitive structure, the proposed filter based on compact array has great promotion in bandwidth, sharpness and stopband depth. The filter has a notable filter capability with 10 dB bandwidth of 0.75 THz at the central frequency of 1.2 THz and incident angle insensitive range from 0°to 60°. Furthermore, the proposed compact array is flexible and can be extended for different unit cells, such as Jerusalem cross,I-shaped, Ⅱ-shaped structures,etc.

Abstract:In order to realize terahertz （THz） metamaterials （MMs） filters with multi-band or wide-band characteristics, the same or different resonance structures are usually combined in the same plane or stacked in multiple layers. THz wide stop-band MMs filter based on Metal-Dielectric-Metal （MDM） structure is presented by placing C-shaped resonance elements of the same size at both ends of the middle dielectric layer, which has the broader stop-band and the better frequency selection. Based on the analysis of the electric field and surface current distributions on the C-shaped resonance elements of the wide stop-band MMs filter, the transmission mechanism of THz wave is discussed in depth, and the filtering mechanism of the filter is revealed. The filtering characteristics of the MMs filter based on MDM structure and Metal-Dielectric （MD） structure are simulated respectively, and the formation mechanism of wide stop-band is revealed. Finally, the MMs filter samples are prepared based on PDMS thin films preparation process and magnetron sputtering, and their filtering characteristics are tested by transmission-type Terahertz Time Domain Spectroscopy （THz-TDS） TDS 1008. The correctness of design, simulation and preparation of wide stop-band MMs filter is verified, which provides reference for the design, fabrication and characteristic research of wide band filters in the future.

Abstract:In the traditional design of electro-optical imaging systems, the optical and electronic subsystems are designed separately. This leads to a reduction in the level of coordination between the parameterization of the both subsystems, resulting in imperfect subsystem compatibility. In order to improve the compatibility between subsystems, shorten a design time and reduce the developments, we propose a co-design method. Based on the end-to-end optoelectronic performance evaluation, the multi-objective and multi-parameter optimization algorithm is used to optimize the configuration parameters of the optoelectronic subsystem. A space infrared imaging system was optimized by this method and imaged good pictures in orbit. The results show that the method has a positive role in optimizing the configuration parameters of the electro-optical imaging system and evaluating the performance of the electro-optical imaging system.

Abstract:As a special periodic structure, sub wavelength gratings have made important progress in filters, reflectors, couplers, sensors and so on. Among them, the non-uniform grating has a great degree of design freedom, which enables it to have the characteristics of wide bandwidth and high reflectivity in terahertz range. Moreover, different grating constants and filling factors will lead to high selectivity in frequency spectrum, thus achieving tunable reflectors. In this paper, a non-uniform, silicon-based grating was designed and fabricated, and its reflection characteristics were measured by terahertz time-domain spectroscopy in reflection mode and calculated by finite element method. The results show that the non-uniform, high-selectivity, silicon-based grating not only has the advantages of wide frequency band and high reflectivity, but also has the characteristics of simple structure, small size, easy fabrication and large process tolerance.

Abstract:A low power 245 GHz subharmonic receiver for gas spectroscopy sensor application has been proposed. The receiver is characterized by low power, high linearity and high integration level. The receiver consists of a four stage common base （CB） LNA, a 2^nd passive APDP （anti-parallel diode pair） SHM （subharmonic mixer）, a 120 GHz push-push VCO with 1/64 divider, a 120 GHz PA （power amplifier） and an IF （intermediate frequency） amplifier. The receiver is fabricated in a SiGe:C BiCMOS technology with f_T/f_max=300/500 GHz. The measured conversion gain is 10.6 dB at 245 GHz with 3-dB bandwidths of 13 GHz , noise figure is 20 dB, and simulated input referred 1 dB compression point is -9 dBm. The receiver dissipates a power of 99.6 mW without 120 GHz VCO-PA chain, and a power of 312 mW with the 120 GHz VCO-PA chain.

Abstract:Mid-wavelength infrared interband cascade photodetectors （ICIP） for high operation temperature applications were designed and grown in molecular beam epitaxy （MBE） system. Clear optical response was measured even at a temperature of 323 K, and the dark current density was 4×10^-5 A/cm^-2 at 140 K for single element device. Based on great material quality of the two-stage ICIP, 320×256 focal plane arrays （FPA） were demonstrated using dry etching. The FPA has a quantum efficiency of 30% from 80 K to 120 K. At 127 K, the device has a noise equivalent temperature difference （NETD） of 55.1 mK and dead pixel rate of 2.3%. Clear infrared images have been taken for a room temperature target with the focal plane arrays at 127 K.

Abstract:The effects of interfacial diffusion of InGaAs/InP heterojunction on the electrical and optical properties of InGaAs epitaxial films grown by all-solid source molecular beam epitaxy （MBE） are investigated. The InGaAs thin films are studied by X-ray diffraction, variable temperature Hall and photoluminescence （PL） measurements. It is found that inserting a layer of InGaAs transition layer grown by As₄ between InGaAs/InP interface can significantly improve the electrical properties of the InGaAs epitaxial film （grown by As₂）, and its low temperature mobility is significantly improved. At the same time, the abnormal blue shift of the PL peak disappears with the improvement of InGaAs optical properties. The research shows that the growth of InGaAs transition layer by As₄ can significantly reduce the abnormal diffusion of As in InP and obtain a sharp InGaAs/InP interface, thus improving the electrical and optical properties of InGaAs films.

Abstract:In this paper, a field-widened Mosaic Grating Spatial Heterodyne Raman Spectrometer （MGSHRS） breadboard was built and described. The calibration procedure is performed, and some broadband backscattering Raman experimental results are given and discussed. It demonstrates that the proposed SHRS technique has good performance for high throughput, high-resolution and broadband backscattering Raman measurements.

Abstract:The spectral sensitivities of FY-4A/GIIRS （Geosynchronous Interferometric Infrared Sounder） in various atmospheric conditions are analyzed using Line-By-Line Radiative Transfer Model （LBLRTM）. On that basis, the information contents of temperature, humidity and ozone in FY-4A/GIIRS are measured by Entropy Reduction （ER） and the Degrees of Freedom for Signal （DFS）, which could evaluate the retrieve capabilities for atmosphere parameters of FY-4A/GIIRS. The results are shown as follows: （1） The sensitivity of temperature and humidity in long wave band of GIIRS are both varied with atmosphere condition, while there is little difference in the sensitivity of ozone under different atmospheric conditions. （2） The application potential for FY-4A/GIIRS with temperature, humidity and ozone profiles inversion is preliminary revealed. Therefore, temperature information content of FY-4A/GIIRS is the largest, followed by humidity under the US Standard atmosphere. （3） The information content of temperature and water vapor in tropical atmosphere is bigger than middle latitude atmosphere.

Abstract:In this paper, methods of data processing and quality control were put forward according to the power spectral and raindrop spectrograph data from the Ka-band millimeter-wave cloud radar in the third Tibetan Plateau Experiment of Atmospheric Sciences Project. The usual physical quantum and the unusual quantum in domestic were also calculated, such as the spectral skewness, spectral kurtosis, average falling terminal velocity of particles and atmospheric vertical velocity. These physical quantities were used to analyze vertical structures and microphysics process of the convective cloud-precipitation over the Tibetan Plateau （Naqu） on 16 July 2015. The results are as follows: （1） The falling graupel convective clouds of the Tibetan Plateau were the strongest from 16:00 to 17:00 Beijing Time （BT） with similar structures as the hail clouds in low altitude. （2） In the same convective cloud, when it was graupel, the spectral skewness varied from “positive-negative- positive-negative” to negative; spectral kurtosis varied from negative to zero; particles in the clouds were tended to be round. （3） When the speed of updraft was greater than or equal to 6 m/s in supercooled water layer（-17~-7℃）, the graupel particles , which were formed into ice crystal accretion with supercooled water drops and rimming growth, were larger than that less than or equal to 4 m/s, in the convective clouds. （4） In the convective clouds, ice crystal and graupel melt in the up-side region 300 m above 0℃ level.

Abstract:The sub-wavelength artificial metamaterials which demonbstrate nearly-perfect absorption of a specific wavelength can overcome the defects of low absorption efficiency, large thickness, and working wavelength limitation of band gap in the infrared photoelectric device application. In this paper, a metal/medium/metal structure is used to construct a sub-wavelength structure that can be prepared over a large area, which can achieve dual-band infrared perfect absorption in the 1-10 μm band. Through analyzing the results of Finite-Difference Time-Domain simulation and experiment, we believe that the high-frequency absorption peak of the absorber is mainly derived from FP resonance interference enhanced absorption; while the absorption peak in the low-frequency infrared band is mainly due to the excitation of the electric dipole resonance and the magnetic resonance mode. By adjusting the size of the upper layer of gold particles in the way of annealing, the positions of the two absorption peaks can be effectively regulated.

Abstract:Thermal parameters of infrared thermal detector include thermal capacity, thermal conductance and thermal response time, reflecting the structure information and performance of detector. Accurate and effective measurement of these thermal parameters is important for device performance evaluation and optimization. A diode-type infrared detector is an important infrared detector. Based on the self-heating effect of diode-type infrared heat detectors, an equivalent electrical test method was developed. The method has the advantages of high precision and easy implementation. The pixel of the self-made diode-type infrared focal plane array was tested by this method. The results were in good agreement with the theoretical analysis, and the feasibility of the method was verified.

Abstract:For staring infrared imaging warning equipment, both wide field of view （FOV） surveillance and accurate target detection are urgently demanded. To meet this requirement, we designed an infrared zoom surveillance system based on concentric spherical lens in this study. It consists of a multi-layer concentric spherical lens and an array of independent continuous zoom cameras. With the spherical lens, a wide FOV is achievable benefiting from its structure. The small camera array enables imaging the target scene into sub-regions. And with the continuous zoom ability, the camera array makes it possible for simultaneous wide FOV surveillance and target identification. When potential targets are detected, further determination and identification can be made by zooming in the corresponding camera to provide high-resolution images. Results show that the modulation transfer function （MTF） curves of the infrared imaging system in the full zoom range are close to the diffraction limit. The zoom curve is smooth avoiding the occurrence of jamming, impact and other adverse phenomena in the zoom process. It provides feasible solution for large field monitoring and high-resolution target identification.

Abstract:In the application of infrared super-resolution imaging, it is actually necessary to improve the subjective visual effects of images. At present, most image super-resolution reconstruction methods based on deep learning are trained and optimized with objective evaluation index as loss function. The subjective evaluation methods are difficult to apply due to the difficulty of quantification. Therefore, this paper focuses on the correlation between subjective evaluation and quantifiable objective evaluation indexes, and finds that the characteristics of phase consistency are highly correlated with subjective evaluation results. Based on this, a loss function based on subjective and objective joint evaluation is designed and applied to the super-resolution reconstruction algorithm of infrared image. Experiments show that this method can improve the subjective visual effect of image while maintaining the objective evaluation score.

Abstract:For the smooth surface and low-texture target, the traditional multi-view geometry reconstruction algorithm was difficult to obtain the ideal result. However, it is difficult to obtain ideal results by simply using the polarization information for three-dimensional reconstruction with ambiguity problem. Using the rough depth map as a prior information can solve the azimuth ambiguity problem. Firstly, calibrated and aligned the polarized camera and the depth camera, and used the normal vector obtained by the rough depth map to correct the polarization azimuth ambiguity, then integrated the corrected normal vector with the rough depth map to obtain a high-precision three-dimensional surface of the object.