Abstract:The InGaAs planar detectors with SiNx film as diffusion mask were fabricated SiNx films were grown by plasma enhanced chemical vapor deposition(PECVD) or by low temperature ICP-CVD inductively coupled plasma chemical vapor deposition(ICPCVD). The photoelectric responses of the detectors made with the two methods were investigated. It turns out that the two kinds of devices have similar performance in the average response rate 0.73 and 0.78 A/W, the average peak detectivity 6.20E11 and 6.32E11 cmHz1/2W-1, and the quantum efficiency 56.0% and 62.0%, respectively. However， the average dark current densities of the detectors is much different, with the values of 312.9nA/cm2 and 206nA/cm2 (-0.1V), respectively. By fitting with experimental data to electrical transport theory, the mechanism of dark current was analyzed. The results indicate that the device using SiNx deposited by ICP-CVD has reduced ohmic dark current in comparison with devices with SiNx deposited by PECVD.

Abstract:As a part of the innovative design of the 140 GHz gyrotron amplifier loaded with confocal waveguide, the design process of the quasi-optical input launcher is comprehensively demonstrated. Owing to the relative insensitivity of the Guassian optics to the frequency fluctuation, the bandwidth of this type of power coupler could be drastically larger than the typical inserted waveguide coupler. The input launcher comprised of the antenna coupler, the mirror transformer and corrugated waveguide guarantees 6.8 GHz bandwidth with respect to >50% power injection efficiency, solving the problem of parasitic resonances and unexpected efficiency shrink simultaneously.

Abstract:The transmission spectra and far-field radiation patterns of periodic metallic aperture arrays are studied in mid-infrared region. We find that the samples have two transmission bands in mid-infrared region. The central positions of transmission bands red-shifts with the increase of the hole-diameter or the lattice constant. The periodic metallic aperture arrays can behave as electrical dipole arrays at the central positions of the transmission bands. The radiation intensity in far-field is strong at the two frequencies. The intensity increase with the decrease of the hole diameter or the increase of the lattice constant.

Abstract:The spin-polarized electron transport through a three-terminal three-arm ring with two quantum dots separately embedded in the upper and lower arms were theoretically studied. The intradot Coulomb interaction on the two dots and the Rashba spin-orbit interaction inside one arm of the ring were taken into account. With the aid of the nonequilibrium Greens function method,we find that even without using any magnetic factors a Rashba induced spin interference effect can drive a spin-polarized current out of the device. By properly tuning the system parameters such as the applied external voltages,the Rashba interaction strength and the dot levels,not only a fully spin-polarized current but also a pure spin current can be obtained. Moreover,the effects of the system parameters on the magnitude, sign, spin-polarization and resonant peaks of the spin-polarized current were also discussed.

Abstract:The nano- TiO2 doped with Nd3+ have been prepared by chemical solution deposition on silicon substrates, followed by cathodic electrochemical process using neodymium nitrate solition as the Nd source. The X-ray diffraction (XRD) pattern revealed that the Nd3 -doped TiO2 thin film has a nano-multi-crystal structure. With the increase of the neodymium content, the surface areas of Nd3 -doped TiO2 thin film is larger and the grain diameter decreases, obviously. The existence of the doped element Nd increases the photocatalytic activity of TiO2, and results in red shift of the absorption limit.The highest photocatalytic activity is achieved with the optimal dosage of neodymiumion at 1.2%.

Abstract:The 2×8 element MnCoNiOdetector array was successfully fabricated with photolithography and wet-chemical etching process. It was shown that the negative temperature coefficient of resistance of the film reaches -3.8% K-1 at room temperature. The typical element of the fabricated detector array exhibits responsivity of about 107V/W and detectivity of about 2×107cmHz1/2/W respectively at bias voltage of ±15V and chopping frequency of 10Hz. The response uniformity of the linear array bolometers is about 5.9%. Our results proved the feasibility of MnCoNiOfilms for linear array bolometer applications, which can possibility be used as new-type uncooled bolometer detectors.

Abstract:La0.7Ca0.3MnO3 thin films with various thicknesses were successfully fabricated on SrTiO3 single crystal substrates via sol-gel method. X-Ray diffraction manifests that all the films have highly preferential orientation. Electrical transport measurement shows a strong impact of film thickness on the physical properties of La0.7Ca0.3MnO3 thin films, which can be attributed to the change of lattice structure of the films substrate induced by strain. Further study indicates that in the films with small film thicknesses, variable range hopping of small polarons is the dominant transport process at high temperatures, and in those films with larger thicknesses small polarons are the predominant charge carriers even at very low temperatures.

Abstract:For typeⅠand typeⅡ linear HgCdTe detector modules, the size of detector chip, Si-ROIC and sapphire electrical lead board in typeⅠmodule are exactly same as those in type Ⅱ module, while the hybrid architecture is different. The thermal stress distribution and warpage of these two modules at cryogenic temperature were analyzed by using finite element method(FEM). The FEM results are in good agreement with experimental phenomenon, and measurements of modules’ warpage at cryogenic temperature verify the rationality of simulated results.

Abstract:DMD(Digital Micromirror Device) is originally designed for visible light spectrum, so it brings lots of problems when DMD is operated under infrared optics. To solve these problems, we provide a telecentric projection optical engine architecture, including projection optical system and illumination optical system. This optical engine employs Kohler telecentric illumination structure, and a field lens is introduced to separate the illumination beams and projection beams. This optical engine has good performance with compact structure, uniform lighting and high energy utilization efficiency.

Abstract:The impact of rotational symmetry of the metamaterial perfect absorber on its performance was investigated. The absorber consists of a metal particle/dielectric-spacer/metal film structure. Using a square metal particle as an example structure and by introducing small air holes to the different y-direction sides of it, we study the absorption properties of the fourfold, twofold and non-rotational rotational symmetrical absorber. The calculated results show that when the polarization of the incident light parallels to x axis or y axis, the same single absorption peak appears in the absorption spectrum. The absorption peak of the twofold rotational symmetrical structure splits into two peaks when the polarization of the incident light parallels to x axis. The absorption peak splits into two peaks no matter the polarization of the incident light parallels to x axis or y axis in the case of non-rotational symmetry. The results of the absorption peak properties with different rotational symmetry may be helpful to design novel polarization-insensitive absorbers.

Abstract:The negative photoresponse characteristics in AlGaN-based p-i-n photodetector have been studied in this paper. The Schottcky contact behavor of p electrode was confirmed to be responsible for this phenomenon. The abnormal photoconductor characteristic was observed in AlGaN photovoltage device under different biases. The persistent photoconductivity characteristic was verified with the capacitance-frequencies experiment under both illumination and dark conditions. The large amount of defects in AlGaN material are considered to be the source of this phenomenon.This paper has systematically studied the abnormal photoresponse behavior and its microscopic mechanism in AlGaN-based p-i-n photodetector, which provides an important foundation for the further optimization of this kind of devices.

Abstract:The lifetime of minority carrier as a function of temperature in n-HgCdTe treated by first anodization and second anodization was measured byμ-PCD and compared. The surface recombination velocity as a function of temperature was simulated from the calculated minority carrier lifetime and measured minority carrier lifetime. The results show that second anodization is an effective way to decrease the density of surface dangling bond and surface defect level, thus reduce the surface recombination velocity and increase the minority carrier lifetime which is beneficial to produce HgCdTe detector with high performance.

Abstract:Quantum efficiency measured at different voltage varies in a wide range. Compensation of the window layer, quality of the main junction and the value of back contact barrier can be derived from the voltage dependent quantum efficiency at different wavelength region. Depletion width and diffusion length of the minority carrier can be calculated from the apparent quantum efficiency. Relationship of the depletion width, diffusion length of the minority carrier and apparent quantum efficiency is presented in the article. A new method to calculate the depletion width and diffusion length of the minority carrier is proposed. Furthermore, we discussed the feasibility of studying thin film solar cells via its voltage dependent quantum efficiency.

Abstract:The background output of the PbS detector is determined by the ratio of the resistance of the detector to that of the reference at the input of the readout circuit. The performance of 1×128 linear photoconductive (PC) PbS infrared focal plane arrays (IRFPAs) was improved by tuning the resistance of the detector with laser. The background out-put of IRFPAs is reduced by tuning the resistance of the detector. As a result, the average responsivity and detectivity of the detector is increased from 4.45×106 V/W to 8.82×106 V/W, and 6.52×109 cm·Hz1/2·W-1 to 1×1010 cm· Hz1/2·W-1, respectively. The dynamic range is also increased from 46 dB to 52dB.

Abstract:A terahertz frequency tripler using resistive Schottky barrier diodes UMS DBES105a was designed. To enhance power capacity and improve conversion efficiency, an anti-parallel diode pair has been used to realize balanced multiplier structure. The equivalent circuit model of the diode has been built and the component parameters were obtained based on the measured results of S parameters. At terahertz band, the field distribution in circuit is seriously affected by the package of diodes. It means that it is not a good way using the traditional method that directly applying SPICE parameters to the field of terahertz. Therefore the electromagnetic model of diodes has also been built. A 220 GHz frequency tripler was fabricated based on the model of diodes. The maximum output power is 1.7 mW and the minimum conversion loss is 17.5 dB. The conversion loss is less than 22 dB from 223.5 GHz to 237 GHz.

Abstract:The differential equations of motion of the cloud droplets in wake vortices were derived. The trajectory and velocity distribution of cloud droplets in wake vortices were obtained by solving the equations of motion. Referring to the parameters of the typical W band millimeter-wave radar, the maximum detection range of wake vortex was analyzed. Then a methodology to simulate the radar Doppler characteristics of wake vortices in cloud was proposed, and the Doppler characteristics of wake vortices in cloud under typical resolution conditions were simulated. The simulation results show that Doppler characteristics of wake vortices in cloud are consistent with the velocity characteristics of wake vortices.

Abstract:The transmission characteristics of millimeter wave and terahertz wave in the nonmagnetic collisional plasma were investigated to meet the need of reentry aero-craft communication. The laws of electromagnetic wave transmission attenuation dependent on electron density, collision frequency, dielectric coefficient change of the antenna window material and electron frequency were obtained. The terahertz wave transmission attenuation (TWTA) is more fader than millimeter wave transmission attenuation (MWTA) in the same plasma. Both TWTA and MWTA in the plasma are at first enhanced and then impeded with increase of collision frequency of the plasma. With the increase of the dielectric coefficient of the antenna window material, MWTW is uplifted and there is a periodic oscillation in the MWTA curve, the periods of which is 5GHz. TWTA experiment was carried out on the shock tube. The results are in agreement with the calculation. Terahertz wave can be likely used as the media to resolve communications blackout on reentry aero-craft.

Abstract:Vanadium oxide thin film was deposited on sapphire by RF magnetron sputtering. The XRD measurement result shows that the thin film is mainly composed of polycrystalline vanadium dioxide. The resistance of the thin film and its optical reflectivity at five different wavelengths were measured simultaneously during the semiconductor-metal phase transition. While both resistance and reflectivity measurements show reproducible hysteresis loops, they have quite different appearance. The optical phase transitions of VO2 at different points are almost the same, thus proving that the sample is uniform.

Abstract:Based on the coupled-wave theory and the phase-matching technique, an improved method for low-order quasi-optical mode launcher is presented. Adjusting the phase difference between the working mode and its satellite modes, an ideal mixture mode with the features of Gaussian field distribution was obtained. Using the proposed method, a 94 GHz TE5,3 quasi-optical mode launcher was synthesized. The numerical calculation shows that the difference between the edge and peak values of field intensity reaches 30 dB. A well-focused field at the aperture with a Gaussian mode content of more than 98% can be obtained，which will reduce drastically the diffraction losses and reflection of power from the cuts.

Abstract:A database of radiative properties of sprays covering the wavelength range of 0.8～20μm and droplets radius range of 1～300μm was constructed. A method of combining database calls for radiative properties acquisition and spectral bands-grey assumption model for processing the non-grey characteristics of sprays was proposed. The result for dimensionless radiative heat flux calculated with the method was compared with the results obtained by this method and got by Mie theory and spectral bands model with Monte Carlo method.It was found that the method of database calls combined with spectral bands-grey assumption model can not only guarantee the calculation accuracy at an acceptable level, but also reduce the CPU time significantly.

Abstract:By using the self-developed calibration of inner blackbody corrected by lunar emission (CIBLE) results of Fengyun-2 (FY-2) satellite, tropical cyclones (TC) intensity was estimated objectively with Dvorak technology. Several strong and supper strong TCs happened in 2012 summer and autumn were selected, when FY-2 lay in the stages of the smooth variation of calibration and the acutely variation one occurred in satellite eclipse period, respectively. As the comparative datum,both MTSAT satellite calibration and FY-2E cross-calibration result were used for the analysis. The results show that CIBLE method can accurately describe the diurnal and annual variation of FY-2E on-orbit calibration slopes, which is the main contributor to the consistent estimations of TC intensity between CIBLE and MTSAT in each intensity stage. Particularly, during the autumn eclipse period, the diurnal variation of calibration slope greatly improves the accuracy of strong typhoon intensity determination even at night. The maximal error of the wind speed in typhoon center has been reduced by 14m/s, which is believed to be a significant promotion for the TC intensity prediction.