Abstract:研究了电子隧穿出射端嵌入1.2 μm厚n型弱掺杂GaAs层的三势垒双阱隧穿结构,观察到了隧穿峰谷比高达36的光生空穴共振隧穿峰.研究证实1.2 μm厚n型弱掺杂GaAs层在光照下产生的大量光生空穴以及空穴隧穿出射端的23 nm宽的量子阱中量子化的空穴能级对空穴隧穿谷电流的限制作用,是导致高峰谷比的光生空穴隧穿现象的主要原因.

Abstract:用助熔剂法生长出掺Bi复合稀土铁石榴石晶体((TbYbBi)3Fe5O12),用(TbYbBi)3Fe5O12替代传统的无磁性Gd3Ga5O12晶体作基底液相外延掺Bi稀土铁鎵石榴石薄膜((TbBi)3GaxFe5-xO12).测量了Tb0.87Yb1.62Bi0.51Fe5O12晶体和Tb2.43Bi0.57Ga0.12Fe4.88O12薄膜/Tb0.87Yb1.62Bi0.51Fe5O12晶体复合结构材料在光通信波段(波长A=1500～1620 nm)处的光透射谱(T)、饱和磁化强度(Ms,0.5×106 A/m)、法拉第旋转温度系数(FTC,5×10-5/K)和法拉第旋转波长系数(FWC,0.05%/nm).所得结果表明:Tb2.43Bi0.57Ga0.1Fe4.9O12薄膜/Tb0 87Ybi 62Bi0.51Fe5O12晶体复合结构材料的综合性能适用于宽带和温度稳定的光隔离器及其他光通讯器件.

Abstract:Ferroelectric PbZrB0.4BTiB0.6B0.6OB3(PZT) and BaTi0.9Sr0.1BO3(BST) multilayers were fabricated by a repeated spin-coating/annealing step of using precursors containing polymer additive.Both the multilayers have more than 90% optical reflectivity at a given wavelength range and the maximum reflectivity increases with the number of growth.The microprobe analysis shows that the multilayers exhibit a lamellar structure consisting of alternating dense and porous layers.The possible formation mechanism for the periodical ferroelectric multilayers is examined,which involves phase separation and pyrolysis of polymer.

Abstract:An data-processing method was developed to obtain the device parameters from the resistance-voltage(R-V) characteristics measured in long-wavelength HgCdTe photodiode.This curve-fitting model includes the diffusion,generation-recombination,trap-assisted tunneling,and band-to-band tunneling current as dark current mechanisms.The fitting procedure was presented in details and the extents of the fitting errors were discussed.By fitting the R-V characteristics of a real device,the applicability of our method has been proved for obtaining the basic parameters of devices.

Abstract:The water surface of Qinghai Lake which is one of China Radiometric Calibration Site of remote sensing satellite(CRCS) is used as the field of radiometric calibration for the infrared channel of remote sensing satellites.As our spin-stabilized geostationary meteorological satellites,FY-2's infrared channel can't realize an absolute calibration on orbit.Since FY-2 is located at the equator of 105 degrees east longitude to Qinhai Lake,the satellite zenith angle is 36 which is larger than the measurable range of the criterion for radiometric calibration site.This study describes a method to calibrate the infrared channels of geostationary meteorological satellites based on the simultaneous measurement of upwelling sea-surface radiance in the South China Sea.The data analysis for FY-2B and FY-2C shows that the South China Sea is a suitable radiometric calibration site for geostationary meteorological satellites.

Abstract:A new statistical method was presented to retrieve the atmospheric temperature and moisture profiles from the satellite radiative measurements. By using the method some ideal and actual retrieval tests were done, and then the retrieval results of the statistical-physical method were compared with that of 1DVAR method. The results indicate that the retrieved temperature is more precise than those of 1DVAR retrieval results at most heights; and the retrieval precision of moisture profiles is lower than the background at middle model layer, and relatively high at other layers, while the 1DVAR method can amend a little to the background of moisture profile. In actual tests, the retrieval results of the temperature profiles are not good enough; the background can be amended only above 400hpa and near the surface, while the retrieval effect of moisture profile is relatively good.

Abstract:MODIS near infrared water vapor products were tested by using the field observations which indicated that the precision of products should be improved and the products were not fit for application over the region. Considering the reasons inducing the error, we improved the algorithm and retrieved water vapor content by adjusting the spatial resolution and using the information of land use type. Our results show that the average relative error is 4.47% ,and the average absolute error is only 0.0456 g/cm^2 , which indicates that the retrievals are much better than the products. By using MODTRAN to analyse, we find good negative correlative relationship between water vapor content and transmittance. According to the relationship, the transmittance was obtained which would be helpful to calculate the surface temperature and other energy parameters.

Abstract:The problem of speckle removal and feature enhancement of SAR image was studied. Traditional speckle removal methods generally result in the lost of image features. Based on the idea of SAR image processing and the prior knowledge of SAR image, we presented an adaptive regularization variation method by constructing diffusion coefficient and regularization parameter. Theoretical analysis and numerical results demonstrate that the proposed method can efficiently depress the speckle and enhance the feature of SAR image.

Abstract:Based on the theory of mode coupling, 3mm band second-harmonic complex cavity gyrotron inner TE0.3-TE0.2- TE0.1 mode converter and collectors were discussed in detail. By adopting structure of corrugated wavegnide with radius tapered and different phase rematch technique, the reliable optimal geometry parameters were obtained. Corrugated waveguide mode converter of 94GHz gyrotron was designed with compact bulk and high efficiency, and the burned patterns measured at the ends of converter were obtained for the gyrotron.

Abstract:The frequency selective characteristics of a new dielectric periodic structure composed of left handed materials were carefully studied by a method which combines the multimode network theory with the rigorous mode matching method. The emphasis was laid on the investigation of the variations of the frequency selective characteristics with structure parameters. The comparisons for the frequency selective properties between RHM and LHM gratings were also shown with some explanations. It is indicated that the bandwidth of the total reflection spectrum for the LHM gratings is much larger than that for the RHM ones. The calculated results are of significance for accurate design of the new millimeter wave frequency selective surface.

Abstract:A MMIC direct detection receiver in principle-model version with a central frequency of 25 GHz and a 4 GHz bandwidth was developed on the background of passive millimeter imaging systems. The operation principle of the receiver was describesd. Each part of the receiver was designed, manufactured, and measured individually and then the complete receiver was tested.

Abstract:The characteristic parameters,such as calibration sensitivity,dynamic range,modified quantity of radiating temperatures of radiometer's reference load and calibration blackbody of a new 3mm band radiometer,were measured.Due to the restriction of 3mm band technology in our country,there are many difficulties for designing and measuring a 3mm band radiometer.In this study,an aperture calibration technology was adopted to measure these characteristic parameters of this 3mm band radiometer by experiments.

Abstract:Special foam screen(SFS) is a novel multi-band passive interference technique.During the processes of improving its interference effect against IR/MMW guidance by increasing the liquid-thickness of air bubbles(d),an abnormal phenomenon occurred so that the interference effect sharply declined.In order to solve this problem,the relevant phenomenon were studied.The results show that the air bubble's multi-interface characteristic is the key factor for SFS to have high effective interference,and when d exceeds dmax(the upper limit of d),the multi-interface characteristic will be severely bated and the SFS has become "degenerate SFS".The ratio of dmax to air bubbles' radius was also calculated,and it is about 0.8882.By controlling easily the working condition of the equipment to discharge SFS,the d won't exceed the dmax.These conclusions can offer the important basis for the tactics application of SFS.

Abstract:A novel microstrip antenna array fed with composite right/left-handed transmission line(CRLH-TL) was presented.The antenna utilizes the positive phase delay of the CRLH-TL to compensate the negative phase delay of the ordinary right-handed transmission line so that the equal phase feeding between the elements of the antenna is guaranteed.As a result,the offset of the radiation beam of the antenna owing to the phase delay is avoided and the gain is increased.The simulation and experimental results indicate that this antenna is of advantages of small dimension,broad frequency bandwidth and easy design for the feeding structures compared with the same type of conventional antenna,and it is applicable to the practical microwave system.

Abstract:The method of spectrum analysis by using neural network algorithm was presented. The convergence of the neural-network algorithm was studied. Simulation examples of spectrum analysis were given. The results show that the approaches of spectrum analysis presented in this study are not involved in plural multiplication operation and plural addition operation. The high accuracy and fast convergence speed are the features of the method presented in this study. Software and hardware of the approach are easily implemented. It is especially fit for the implementation of software and hardware about DSP. Therefore, the methods of spectrum analysis proposed in this study are effective.

Abstract:Based on the modal matching method, frequency selective surfaces of multiple crossed dipoles element was analyzed. The electric field based function for multiple crossed dipoles aperture element was presented by taking the electric field based function of crossed dipoles aperture element. The frequency selective surfaces of multiple crossed dipoles element has dual-band, which will be widely applied in microwave, infrared and optics.

Abstract:基于傅里叶红外光谱仪成功研制了固体材料光谱发射率测量装置,它由一个试样加热炉、一个参考黑体炉、水浴环境腔体及真空系统等组成,可以实现100～1500 ℃及光谱0.66～25 μm范围内固体材料光谱发射率测量.参考黑体用于对系统的标定,水浴环境腔体和真空系统用来消除环境和大气的影响.装置调试后对某种航天用材料做了测试实验,得到了很有规律的结果.估计了系统的不确定度:发射率不确定度小于2.27%(3δ,ε=0.9),6.80%(3δ,ε=0.3).

Abstract:大气红外探测仪AIRS的核心是一个光栅光谱仪序列,2378个红外探测器分装在17个探测器序列上,本文以实例说明了由于探测器序列在视轴方向有偏移,即空间错误定位误差给AIRS的观测值带来的影响及其光谱分布特征,以及观测值误差对后继红外晴空订正和大气廓线反演的影响.建议以后在设计同类仪器时要避免探测器序列错误定位问题,或选用干涉式分光系统.

Abstract:Set out from the connotation of the test and evaluation of the smoke jamming,the evaluation method of the smoke jamming was discussed.The evaluation rules of jamming effectiveness were presented.For electro-optical guided system,a jamming is effective or not is according to the changing of the tracking error,its guidance accuracy or its hit probability,The test result of the smoke screen's countering laser guided weapon under typical weather environment and different transmissivity of bomb release modes were given.The conclusion that the smoke is an effective jamming way was obtained.