Abstract:Introduction Mercuryselenideisan typezero gapsemiconduc torinzincblendestructure.ThemodificationHgSe:Fe withanirondopingnFe>5×1018cm-3leadstoa mixed valenceregimeofFe++/Fe+++systemanda pinningoftheFermi energytotheenergyofirondonor about210meVabovethebandedge[1].Pronounced short rangecorrelationeffectsinFe++/Fe+++system giverisetoadrasticmobilityincrease,sothatHgSe:Feasahostmaterialfornano structuredsystemsen surestheobservabilityofanyquantumeffect[2].1RecentexperimentsonHgSe:Feinmag n…

Abstract:Most porous silicon samples studied have been oxidized in various degrees. Oxidized porous silicon and the nanoscale silicon particles embedded oxidized silicon have similar structures and luminescence characteristics. Both of them consist of a great quantity of nanoscale silicon particles, each of which is surrounded by an oxidized silicon layer, and can be named as nanoscale silicon/oxidized silicon systems. They are the most strongly studied and very promising silicon-based luminescence materials. In this article, the photoluminescence mechanisms of the nanoscale silicon particles/oxidized silicon systems were summarized and discussed. The related research works finished by our group in Peking university were briefly introduced.

Abstract:研究了一些半导体低维结构的压力光谱．测得平均直径为26、52和62nm的In0.55Al0.45As／Al0.5Ga0.5As量子点发光峰的压力系数分别为82、94和98meV／GPa．表明这些发光峰具有Г谷的特性，这些量子点为Ⅰ型量子点．而平均直径为7nm的量子点发光峰的压力系数为-17meV／GPa，具有X谷的特性．所以这种小量子点为Ⅱ型量子点．测得ZnS：Mn纳米粒子中Mn发光峰的压力系数为-34．6meV／GPa，与晶体场理论的预计一致．而DA对发光峰基本不随压力变化，表明它应该与ZnS基体中的表面缺陷有关．测得ZnS：Cu纳米粒子中Cu的发光峰的压力系数为63．2meV／GPa，与ZnS体材料的带隙压力系数相同．表明Cu引入的受主能级具有浅受主的某些特点．测得ZnS：Eu纳米粒子中Eu发光峰的压力系数为24．1meV／GPa，与晶体场理论的预计不同．可能和Eu的激发态与ZnS导带间的相互作用有关．

Abstract:The ultrafast process in semiconductor was studied by using femtosecond pulse laser. The momentum relaxation of carriers excited by laser was detected by using ultrafast photo-voltage spectra. The time of momentum relaxation of carriers in semiconductor Si is about 70 femtosecond, which is related to the probability of carrier-carrier scattering. In SiGe quantum dot, it is about 130 femtosecond due to the decrease of carrier-carrier scattering. The energy relaxation and diffusion processes can be measured by ultrafast reflection spectra. The time of energy relaxation of carriers excited by high energy laser is about several picoseconds, which is related to the probability of carrier-phonon scattering, and the diffusion time of carriers excited by low energy laser is about several hundreds picoseconds.

Abstract:Near infrared femtosecond laser micro/nano-fabrication using in transparent condensed matters like glass and polymers was reported. Femtosecond laser induced refractive index change was used for fabrication of gratings and other elements inside silica glass. Drilling from rear surface in contact with water, microholes with large aspect ratio were machined in soda-lime glass; With the change of laser focus inside two-photon absorption polymer, straight and wavy lines are polymerized.

Abstract:通过多种光谱手段研究了GaNAs量子阱和体材料中的局域态和非局域态的不同光学特性．在超短激光脉冲激发下，第一次在GaNAs／GaAs量子阱发光光谱中，观察到非局域激子发光．选择激发光谱表明，局域中心主要聚集在GaNAs、GaAs异质结界面．在低N含量的GaNAs体材料发光光谱中，除了与N相关的局域态发光外，也发现发光特性完全不同的GaNAs合金态发光．这些结果为理解Ⅲ-Ⅴ-N族半导体的异常能带特性具有十分重要的意义．

Abstract:The development of spintronics and spintronic devices, the applications of spintronic devices as well as the research subjects and current status on semiconductor spintronics are reviewed. Our research results on the relaxation of polarization and coherence of electron spin are given for GaAs.

Abstract:Microscopic luminescence and Raman scattering study was carried on AlInGaN quaternary alloy. Based on the analyses of SEM image and cathodoluminescence spectra measured around V-defects, the correlation between V-defect formation and indium segregation was clarified. Raman scattering of thin AlInGaN epilayers was investigated by using the short wavelength excitation of 325nm laser line. The frequency shift of A_1(LO) phonon induced by the change of Al composition in alloy was observed. The Raman scattering of LO phonons was found to be resonantly enhanced with outgoing resonance, and it is attributed to the cascade-like electron-multiphonon interaction mechanism.

Abstract:By field experiment in water sampling for chemical analysis and synchronous measurement of reflected light spectrum of water, the optimal channel combination models were obtained to retrieve chlorophyll-a concentration and suspended sediment concentration from remote sensing data of FY-1C multi-channel scanning radiometer, Landsat-5 TM, SeaWiFS of Seasat and a supposed set of remote sensing channels. A method retrieving water quality parameters by satellite remote sensing was suggested, in which the atmospheric transmittance and reflectance were determined by the reflected light spectrum of standard reflecting board on water and satellite remote sensing images themselves for the atmospheric calibration. The models and methods were used to retrieve the eutrophic degree, its space distribution and its change with year of Tai lake and Dianchi lake, which are typical eutrophic lakes of china, in 1980s and 1990s. The results of this study could be as the bases for operational satellite remote sensing of water quality of lake.

Abstract:This study is concerned with the calculation of atmospheric transmittance and weighting functions of IRSR based on GENLN2 spectral transmittance database and RTTOV7 fast transmittance model. The results indicate that most weighting functions of IRSR are similar with that of HIRS/3. It also shows that the peak energy contribution levels satisfy the designed requirement basically.

Abstract:The photoluminescence of self-assembled InAs/GaAs quantum dots, which are 7.3nm in height and 78nm in base size, was investigated at 15K under hydrostatic pressures up to 9GPa. The emissions from both the ground and the first excited states in large InAs dots were observed. The pressure coefficients of the two emissions are 69 and 72 meV/GPa respectively, which are lower than those of small InAs/GaAs dots. The analysis based on a nonlinear elasticity theory reveals that the small pressure coefficients mainly result from the changes of the misfit strain and the elastic constants with pressure. The pressure experiments suggest that the excited state emissions originate from the optical transitions between the first excited electron states and the first excited hole states.

Abstract:The periodically poled characteristics of LiNbO_3 doped 5mol% MgO were investigated and the domain reversal field was found to be 3kV/mm. According to the influence of MgO doped on the crystal defect, the decrease reason of the domain reversal field was explained. By using short-pulse field, the periodically poled grating was successfully fabricated in 1.0mm thick MgO:LiNbO_3. Second harmonic green light generation in periodically poled MgO:LiNbO_3 was demonstrated. The green light power of 3.5mW at 532nm is obtained when the fundamental power is 75mW, and the conversion efficiency is 4.6%.

Abstract:The testing data of millimeter-wave collision-warning radar were firstly analyzed by time-frequency method. Then a constant false alarm rate (CFAR) scheme for millimeter wave collision-avoidance radar was designed on the basis of the clutter statistics distribution rule. This proposed method can change the threshold with the clutter to make the false alarm rate constant. The testing result and the performance of this CFAR processor were presented. It is shown that this method is practical in the project.

Abstract:The model of buffer gas effect on optically pumped submillimeter wave laser was established. And the deactivation rate of buffer gas was deduced by quantum theory, so that the buffer gas effect could be calculated quantificationally. The CO2-9(R30) laser pumping NH3 67.2um line was calculated theoretically and measured experimentally. The experiment results agree with the theoretical calculation. This work would be in favor of finding high-efficient buffer gas of optically pumped submillimeter wave laser.

Abstract:最大类间方差法是一种常用而有效的图像分割算法，但由于计算量较大，不适宜于红外成像跟踪系统中高帧频的实时图像处理。在分析类问方差曲线特征的基础上，提出了一种二分逼近型快速最大类间方差算法．该算法通过对最大类间方差函数求导并利用二分逼近的方法逐次逼近最佳阈值点．理论分析和仿真结果证明，该算法的计算量较一般的最大类间方差算法有较大幅度的降低，具有实时性好，易于工程实现等优点．

Abstract:基于多晶硅p-n结正向压降的温度特性,应用标准CMOS工艺,结合体硅微机械加工技术,研制成功非制冷红外微测辐射热计.本文详细分析了横向多晶硅p+p-n+结的温度特性,给出了正向压降温度变化率的理论表达式和实验测量值;并描述了微测辐射热计的设计思路和制作工艺.实验结果表明在室温(284～253K)附近,横向多晶硅p+p-n+结正向压降的温度变化率为1.5mV/K;在3～5μm红外波段,微测辐射热计的电压响应率为5.7×103V/W,黑体探测率D*为1.2×108cm.Hz1/2.W-1.

Abstract:The mean shift algorithm is a nonparametric statistical method for seeking the nearest mode of a point sample distribution. In the color image sequence, the mean shift algorithm is an efficient method for tracking object. However, there is a singular grey space for representing the infrared object in the infrared object tracking scenario. Due to the lack of the information for the object representation, the object tracking based on the mean shift algorithm may be lost in the infrared sequence. To overcome this disadvantage, a new scheme that is to construct a cascade grey space is proposed. Moreover, for the different infrared image sequence, different strategies are used to generate different cascade grey spaces. The experimental results of two different infrared image sequences show our new scheme is efficient and robust for the infrared small object tracking and infrared object in the severe clutter background tracking.

Abstract:With the development and the application of visible-IR image fusion techniques in color vision night, evaluating the performance of image-fused algorithms is becoming an important aspect. In this study, three basic visual evaluation factors, target detection, details and colorfulness, were presented for evaluating perceptual quality of color fused images, and the degree of correlation between the perceptual quality and the three evaluation factors was investigated. Visual evaluation experiment on the color images fused visible and IR images of ten scenes by four fusion algorithms was conducted. The experimental results show that the fuesd images have good performances in target detection, the correlation coefficient between the perceptual qulity and details is 0.89, and the correlation coefficient between the perceptual qulity and colorfulness is 0.75 . It indicates that details are the main factor and the colorfulness plays an important role when targets are beyong the detected level.