Abstract:Based on the theory of plasmon resonance， we present a photon plasma ridge waveguide consisting of a metal/graphene/Al₂O₃/graphene stacking structure. The modulation performance is optimized through the design of the waveguide and plasma structures by analyzing the microscopic mechanism of photoelectric reaction. A low-insertion-loss near-infrared electro-optic modulator with a modulation rate of 730 GHz， energy consumption of 0.7 fJ/bit， and 3-dB bandwidth of 3.66 THz is achieved.

Abstract:To improve optical absorbance in the solar spectrum region as well as to reduce solar emittance in the infrared region， a new solar absorber structure based on the double W-SiO₂ cermet layers was proposed and optimized. The factors which affect the spectral selectivity of the solar absorber such as the IR reflectance property of metal， and the volume fraction of the absorption layer were investigated. A series of W-SiO₂ cermet films with different values of volume fraction were prepared onto Si and K9 glass substrates. The measured optical constants as well as those deduced from the data fitting were used to optimize performance of the selective solar absorber. Based on the optimized parameters， the solar absorber structure with the layer parameter， consisting of that W （~150 nm） / W-SiO₂ （94 nm， 0.67HVF） / W-SiO₂ （34 nm， 0.27LVF） / SiO₂ （47 nm）， was fabricated using a magnetron sputtering system at room temperature. The experimental results agree well with the simulated ones， showing an average optical absorption of 95.3% in the wavelength region of 250～1500 nm， and a low thermal emittance of about 0.124 at 600 K in the broad wavelength region of 0.25～25 μm. Due to the simple components and high efficiency， the solar selective absorber based on the structures consisting of double W-SiO₂ cermet layers shows a good potential for practical applications in the future.

Abstract:The interface changes of multi-layer HgCdTe P-on-N epitaxial materials grown by molecular beam epitaxy （MBE） before and after high temperature thermal annealing were studied. It is found that high temperature thermal annealing causes the change of the interface layer of HgCdTe P-on-N structure and destroy the original designed structure. This change can be controlled to some extent by thermal annealing conditions. At the same time， the structural changes of P-on-N before and after thermal annealing are simulated numerically， and the effects of different changes on the energy band and light current are studied.

Abstract:The relation between the film thickness and the growth conditions in the liquid phase epitaxy （LPE） process is discussed. A convolution approach for the thickness is developed on the assumption that the growth rate is determined by the solute diffusion process. Using this convolution expression， the relations between thickness， growth time and cooling rate can be obtained for various LPE techniques. Moreover， the convolution algorithm can also be used to deal with some complex growth conditions， such as nonuniform cooling rate， nonlinearity of the liquidus curve and the finite growth solution.

Abstract:Multi-component heterostructure nanocomposites can not only inherit the original properties of each component， but also induce new chemical and electronic properties through the interaction between the components. The heterostructure zeolitic imidazolate framework/NaGdF₄：Yb，Er （ZIF-67/NaGdF₄：Yb，Er） was prepared by a stepwise synthesis strategy. And it avoided agglomeration and quenching of upconversion （UC） nanoparticles， and displayed better stability. In the heterostructure nanocomposites， ZIF-67 is employed as an energy transmission platform under 980 nm excitation. Compared to pure NaGdF₄：Yb，Er nanorods， the UC photoluminescence of heterostructure ZIF-67/NaGdF4：Yb，Er is tuned from green to red owing to the synergistic effect of each component.

Abstract:avalanche photodiodes （APD） have been fabricated using high quality GaSb-based AlInAsSb quaternary digital alloy grown by molecular beam epitaxy （MBE）. To overcome the tendency towards phase segregation of random alloy， a digital alloy technique with migration-enhanced epitaxy growth method was employed， using a shutter sequence of AlSb， AlAs， AlSb， Sb， In， InAs， In， Sb. The HRXRD curve shows sharp satellite peaks and almost perfect lattice matching. The smooth surface morphology can also be observed on the AFM image. Using optimized digital alloy， AlInAsSb separate absorption， grading， charge， and multiplication （SAGCM） APD was grown and fabricated. At room temperature， the device showed high performance with low dark current density of 0.95 mA/cm² at 95% breakdown and maximum stable gain before breakdown as high as 100， showing the potential for further applications of optoelectronics.

Abstract:Based on the silicon micromachined technology， a W-band 4-way silicon waveguide power splitter/combiner was designed and fabricated in this paper. The silicon waveguide has been realized by dry etching and wafer level bonding on an 8 inch silicon wafer. According to the characteristics of silicon micromachining， a waveguide power splitter/ combiner based on H-plane T-junction and 3dB coupler was designed. This silicon splitter/combiner exhibits extremely low loss. A silicon power combined PA module was developed by using this silicon power splitter/combiner together with four 2W GaN MMICs. The output power is between 7.03W and 8.05W across the frequency range of 92 to 96GHz with an input power of 30dBm， and the typical PAE is 15%. The average combining efficiency is 88%.

Abstract:A simple and effective design method for high cut-off frequency Schottky barrier diode is proposed and implemented. The cut-off frequency of the processed Schottky barrier diode is about 800 GHz， which can reach about 1 THz with the optimized parameters through the test results and simulation data in SMIC 180 nm process. The integrated detector including antennas， matching circuit and Schottky barrier diode is completed， whose tested responsivity could achieve 130 V/W and noise equivalent power is estimated to be 400 pW/ at 220 GHz. The imaging experiment of invisible liquid surface in ceramic bottles has been completed and good results have been achieved.

Abstract:Gyrotron can achieve high peak power and high average power output in millimeter wave and terahertz band， which has important application requirements. Based on the beam wave interaction theory of gyrotron， a 140GHz gyrotron is designed for test and aging process of the relevant elements of electron gyrotron heating in magnetic confinement fusion. The goal is to achieve a maximum output power of not less than 50KW which can operate in pulse and continuous mode， and a certain range of frequency and power adjustment to meet the needs of the test. According to the design results， the gyrotron is developed and tested. A maximum output power of 56 kW is achieved corresponding to the cathode voltage of -37.2 kV， the modulation anode voltage of -12.19 kV， the second anode voltage of +11 kV， the beam current of 3.4 A and the magnetic field of 5.3 T. The power can be adjusted by changing beam current and magnetic field. In the same way， the frequency can be adjusted within 80 MHz. The theoretical calculation results of starting current， power and frequency are compared with the experimental results， which are in good agreement. In the preliminary experiment， overheating of the window was observed with an output power of 52 kW for 30s’ operation， so the continuous operation experiment was carried out with the power reduced to 20.3 kW， under this power level， the continuous operation state of the gyrotron is stable， which can be used for the subsequent work for test and aging of fusion elements.

Abstract:This paper proposes a training sample selection algorithm for radar based on direct estimation of the CUT clutter characteristics. The proposed method directly uses the sub-aperture covariance matrix of CUT to characterize the clutter. Since the estimation process doesn't depend on training samples， the estimation of CUT is not affected by the outliers. Moreover， considering the existence of target signal in the CUT， the proposed method removes the target component from the sub-aperture covariance matrix of CUT based on clutter covariance matrix reconstruction， which utilizes the clutter Capon spectrum integrated over a sector separated from the location of target. Compared with the traditional generalized inner product algorithm which uses single snapshot to calculate the detection parameters， the new algorithm uses the sub-aperture covariance matrix of the samples to characterize its statistical characteristics， obtaining more stable results. The simulation results show that the proposed algorithm selects training samples more accurately.

Abstract:A theoretical model of the infrared spectral emissivity measurement of materials using the integrated blackbody principle was established. The effects of the effective emissivity of the non-isothermal integrated blackbody cavity， the observation coefficient and the temperature drop during the sample material push-out were investigated. The device of the infrared spectral emissivity measurement using the integrated blackbody principle was set up which used a Fourier-Transform infrared spectrometer as the infrared radiation detection instrument. The effective emissivity of the integrated blackbody cavity was simulated using Monte-Carlo ray tracing method and the associated validation experiments were carried out. The effects of non-ideal factors， including the size-of-source effect and linearity of the spectral responsivity， on the infrared spectral emissivity measurement using the integrated blackbody principle were investigated. The experimental measurements of the infrared spectral emissivity of a graphite material were carried out at 1000℃， 1300℃ and 1500℃， respectively. The results in this article are in good agreement with the literature data better than 5%， which verifies the feasibility of the emissivity measurement method using the integrated blackbody principle at high temperatures.

Abstract:The atmospheric infrared ultra-spectral sounder （AIUS） is one of the main loads of GF-5 satellite. It is used to obtain the vertical distribution information of various atmospheric trace gases through solar occultation observation. And accurate spectral calibration is the key and foundation for its data quantitative inversion. Ultra-spectral resolution and no matching on-board spectral calibration equipment make it is difficult to realize high precision on-orbit spectral calibration for AIUS. A multi-line linear fitting algorithm based on atmospheric characteristic lines is proposed， which employs the key technologies such as Doppler shift correction， lines selection and accurate peak position determination to improve the spectral calibration accuracy. And after the successful launch of GF-5 satellite， a series of spectral calibrations and accuracy analysis are carried out for AIUS. The results show that this algorithm can achieve high precision spectral calibration of AIUS. The mean absolute deviations of MCT and InSb channels are 0.00437cm^-1 and 0.00389cm^-1， which are less than 0.008cm^-1 required by trace gas inversion application.

Abstract:Photon counting laser altimetry could detect the continuous elevation of the earth’s and vegetation’s surface. But， whether a single photon event could occur in a certain period is a random event according to echo energy and detection probability. Therefore， the set of received single photon events can not accurately represent the strength of an echo， which makes it difficult to determine the starting position in monopulse detection， and may cause an error when estimating vegetation’s canopy height. By establishing the photon counting detection model of vegetation， the error of canopy height caused by the principle of single photon detection is analyzed and calculated in this paper. Experimental results showed that the average elevation of the first detected signal photons was 2.435m lower than the DSM provided by LIDAR data from taiga forest. Still， it is helpful to reduce the error by increasing the energy or reducing the divergence angle of of emitted laser. And the errors of forests with higher canopy density and leaf area index are smaller accordingly.

Abstract:Aiming for development of geostationary orbit （GEO） millimeter-wave atmospheric sounding technology， the sophisticated end-to-end simulation experiments based on the candidate real-aperture radiometer schemes for China future GEO atmospheric sounding mission， including 50~425 GHz observation brightness temperatures forward and atmospheric profiles retrieval， are conducted to quantitatively examine the accuracy of GEO observation brightness temperature and the estimated atmospheric temperature and humidity profiles under the tropical cyclone conditions in this paper. Then the various factors affecting the accuracy are analyzed. The results show that the two major factors of the radiometer， the antenna beam width and the system noise， play the difference roles in the reduced accuracy of GEO observed brightness temperature for each frequency channel. The accuracy of the retrieval atmospheric temperature and humidity profiles from GEO sounding simulation is comparable to that of the polar orbit. And the contrast results of the retrieval profiles with and without 380 GHz and 425 GHz bands indicate that the accuracy of retrieval profiles can be improved effectively by the new terahertz bands of GEO atmospheric sounding. In additional， BG reconstruction algorithm can also decrease the retrieval errors. The above research can provide scientific basis and technical support for the development decision maker of GEO millimeter-wave atmosphere sounding research.

Abstract:To reduce the dispersion mismatch effect on FMCW measurements， a method of eliminating dispersion mismatch by the forward and reverse tuning of an external cavity tunable laser is proposed. When the external cavity tunable laser is combined with an optical fiber path， the system produces a dispersion mismatch effect， which is manifested as peak broadening and shifting of the target signal. The ranging value changes with the increase in the tuning bandwidth， resulting in measurement instability. To solve this problem， the paper studies the system dispersion mismatch characteristics of the external cavity tunable laser in forward and reverse tuning. The results show that the dispersion trend is a symmetrical distribution of the forward and reverse tuning. The paper establishes the dispersion mismatch model of the forward and reverse tuning system. On this basis， dispersion cancellation is realized by forward and reverse tuning of the external cavity laser. This method does not require calibration of the dispersion coefficient of the system in advance nor cyclic iterative compensation. A single measurement can complete the dispersion compensation for the system， which provides a way to improve the efficiency of dispersion compensation.

Abstract:In recent years， there is an increasing interest in polarization 3D imaging technology， due to the advantages of high accuracy， long imaging distance and immune to the stray light polarization. However， the accurate acquisition of normal vector information of the surface is quite difficult by utilizing the reflected light characteristics of the surface， which constitutes an obstacle to the development of the technology. The mixture of specular reflected light and diffuse reflected light is the main factor for deteriorating the performances of polarization 3D imaging. In this review， the basic principle of polarization 3D imaging technology and polarization characteristics of reflected light were introduced. Meanwhile， the development of polarization 3D imaging technology was also reviewed. Finally， the problems and the future improvement in polarization 3D imaging are summarized and prospected.

Abstract:A theoretical model of high frequency characteristics of staggered grating slow-wave structure at G band frequency is presented based on the eigen function method. Considering the convergence of spatial harmonic series， the loss parameters well as dispersion curve and coupling impedance are then derived and verified by simulation software. The results of the theoretical model match well with those from simulation， the error of dispersion characteristics is less than 0.1%， and the errors of coupling impedance and loss are both less than 10%， which proves the reliability of the theoretical model. It shows that the model is universal for structures with arbitrary staggered distance or different grating height and can be converted to double grating or rectangular waveguide grating in two extreme cases. The loss mainly occurred on the beam tunnel region of the structure and there is less loss on the top and bottom of slot area.

Abstract:Stripe noise is a common phenomenon in remote sensing image due to non-uniformity problems. The stripe noise seriously affects the image quality and subsequent applications. Unlike most destriping methods， structural properties of stripe noise are analyzed and the purpose of destriping is achieved by separating the stripe components. In the proposed optimization model， the L0-norm-based is used to describe global sparse property of stripes. In addition， difference-based constraints are adopted to describe the smoothness and discontinuity in the along-stripe and across-stripe directions， respectively. In order to better protect the detailed information of an image， an edge weighting factor is introduced in the constraints of across-stripe direction. Finally， the proposed model is solved and optimized by the alternating direction method of multipliers （ADMM）. The algorithm is verified by the in-orbit images obtained by Advanced Geosynchronous Radiation Imager （AGRI） in comparison with typical destriping methods. Experimental results show that the proposed algorithm completely eliminates the stripe noise and preserves more details， which shows better qualitative and quantitative result.