HCN激光器及亚毫米波波长的测量

简要地描述工作在亚毫米波段的连续波HCN(氰化氢)气体激光器的结构及工作特性,并分别应用反射光栅法及法布里-珀罗干涉仪法对HCN激光器的输出波长进行测量.其测量精度反射光栅法达到1%;法布里-珀罗干涉仪法达到0.1%.     

A new method for complex spectral measurement in millimeter and submillimeter wave range

New method for measuring complex transmission or reflection coefficients has been proposed and demonstrated using a simple setup. High measurement quality was achieved: phase sensitivity ～ 0.005 rad., amplitude reproduceability ～ 1%, dynamic range to ～ 10⁷ ÷ 10⁸ (previously 10⁴), phase shift range to be measured 10⁵. It is effective for BWT-Spectroscopy due to the absence of any mechanical adjustments during electronic frequency scan.     

Design and field-of-view calibration of 114-660-GHz optics of the Earth observing system microwave limb sounder

This paper describes the optics design and field-of-view (FOV) calibration for five radiometers covering 114-660 GHz which share a common antenna in the Microwave Limb Sounder instrument on the National Aeronautics and Space Administration's Aura satellite. Details of near-field pattern measurements are presented. Estimated systematic scaling uncertainties (3/spl sigma/) on calibrated limb emissions, due to FOV calibration uncertainties, are below 0.4%. 3/spl sigma/ uncertainties in beamwidth and relative pointing of radiometer boresights are 0.006/spl deg/ and 0.003/spl deg/, respectively. The uncertainty in modeled instrument response, due to the scan dependence of FOV patterns, is less than /spl plusmn/0.24 K equivalent black-body temperature. Refinements to the calibration using in-flight data are presented.     

Metal mesh couplers using evanescent waves at millimeter and submillimeter wavelengths

In this paper we introduce a metal mesh evanescent wave coupler that makes use of evanescent wave coupling between a metal mesh and a dielectric plate, as a quasi-optical component for millimeter and submillimeter wavelengths. The transmission properties of this type of couplers have been investigated experimentally and theoretically for both capacitive and inductive metal meshes in the frequency range from 40 GHz to 60 GHz. The transmittance of a capacitive metal mesh evanescent wave coupler can be adjusted more than 70% by changing the spacing between the capacitive mesh and the silicon plate less than 0.15 mm at around 57 GHz.     

Millimeter and submillimeter detection using Ga1−xAlxAs/GaAs heterostructures

We have shown that a Ga_1?xAl_xAs/GaAs heterostructure can be used as a sensitive tunable detector of mm-wave/sub-mm-wave radiation. The mechanism for detection requires the application of a magnetic field varying from approximately 0.2T at 94GHz (3.2mm wavelength) to 6.2T at 2500GHz (119μm wavelength). The responsivity and N.E.P. at 3.2mm have been roughly estimated at 200V/W and 5×10^?11W/?Hz respectively. The speed of such a detector could be several orders of magnitude greater than comparable InSb detectors.     

户外型探测臭氧和气溶胶激光雷达系统研制

激光雷达探测臭氧和气溶胶垂直廓线分布近年来在环境监测领域获得广泛应用。介绍了一套可同时用于探测臭氧和气溶胶浓度的激光雷达系统。采用Nd:YAG激光器,通过二倍频器和四倍频器分别产生532 nm和266 nm激光光源,基于受激拉曼散射原理,在两根拉曼管中分别充有氘气和氢气,产生拉曼频移光289 nm,299 nm,通过差分吸收算法原理反演垂直空间臭氧浓度廓线,通过米散射算法原理来反演气溶胶浓度廓线。水平扫描试验结果显示,雷达系统的探测结果与近地面点式臭氧分析仪测量结果有较好的一致性,相对误差小于10%。在安徽合肥科学岛外场观测结果表明:臭氧探测高度,白天可以达到3 km,晚上可以达到5 km,气溶胶探测高度,白天可以达到10 km,晚上可以达到15 km。     

Hail embryons detection in clouds using passive and active radars in millimeter and submillimeter wave bands

Two detection methods of hail embryons in a cloud are discussed in the paper: combined passive/active and purely active sensing of a convective cloud from board of air or space carrier. The first method makes it possible to determine the spectral dependence of absorption coefficient by oversized drops in convective cloud in the millimeter (MM) and submillimeter (SbMM) wavebands. With this purpose a highly sensitive 16-channel Dicke radiometer is used. In the second method a multiwave (12 wavelength) active radar is used to determine the spectral dependence of backscatter coefficient in the same wavebands. Variation of these spectral characteristics in time makes possible the detection of physical processes taking place in a cloud, such as drops drowth and evaporation, as well as transition of oversized drops into the overcooled state. The instant of water/ice phase transition in oversized drops is determined in both methods by means of active radar in SbMM waveband (in the transparency “window” of ice and atmosphere, 0.64 mm). Corresponding hardware, antennas, and wavelengths are considered for active/passive and purely active sensind of clouds. The effect of antenna beamwidth in SbMM on anomalous backscatter is discussed.     

The study of the target emissivity and detection using a superconducting detector in the submillimeter wave region

This paper researches mainly the radiation characteristics of the target and detecting techniques by superconducting detector in the submillimeter wave(SMMW) region. The calculation of transition wavelength(TW) between Planck and Rayleigh-Jeans is given out. The experiment of detecting different targets is finished by use of superconducting detector possessing high performances. Through the experiments in paper we can select and determine the wave bands of SMMW detecting and imaging system. The many novel theoretical analyses and experimental results are expressed in Figs and tables of the paper. Finally, a part of calculating results and experimental datum detected by a superconducting detector in SMMW regions are given in this paper.     

Antenna pattern and penetration measurement using spectrumanalyzers

A convenient method for measuring synthetic-aperture radar (SAR) azimuth antenna patterns and microwave penetration of soil or trees using spectrum analyzers and amateur-radio antennas is described. The received power of a ground receiver is estimated for several SARs. This estimation suggests that spectrum analyzers can be used for ground measurement during SAR observation. Results of in situ experimental measurements which were made during the NASA/JPL DC-8 SAR campaign in summer 1990 in the JAROS/NASA JERS-1 simulation project are presented. A discussion and perspectives on applications for JERS-1 SAR are included     

介质前后双重臭氧处理实现锗/氧化铪间界面钝化

The physical and electrical properties of a Ge/GeO₂/HfO₂/Al gate stack are investigated.A thin interfacial GeO₂ layer（ 1 nm） is formed between Ge and HfO₂ by dual ozone treatments,which passivates the Ge/high-k interface.Capacitors on p-type Ge substrates show very promising capacitance-voltage（C-V） characteristics by using in situ pre-gate ozone passivation and ozone ambient annealing after high-k deposition,indicating efficient passivation of the Ge/HfO₂ interface.It is shown that the mid-gap interface state density at the Ge/GeO₂ interface is 6.4×10¹¹ cm^-2·eV^-1.In addition,the gate leakage current density of the Ge/GeO₂/HfO₂/Al gate stack passivated by the dual ozone treatments is reduced by about three orders of magnitude compared to that of a Ge/HfO₂/Al gate stack without interface passivation.     

Splice loss measurement using local launch and detect

This paper reports a new method for measuring absolute splice loss using a local launch and detect technique. The theory of the procedure and the calibration routine are described. Results with single-mode fiber splices are presented and compared with the cutback measurements.     

基于双波片的偏振调控和偏振测量技术

针对双波片偏振调控结构,基于Stokes-Mueller矩阵偏振算法,对双1/4波片和双1/2波片的偏振调控机理作了详尽的理论分析,得出调控偏振态与双波片快轴方向之间的关系,并追迹其在庞加莱球上的运动轨迹.基于双波片调控结构搭建偏振测量系统,根据入射和出射Stokes矢量构建了投影关系矩阵算法,完成了待测元件Mueller矩阵的测量,并分析了波片的快轴方向误差和位相延迟误差对Mueller矩阵测量结果以及对出射偏振态调控精度的影响.分析结果表明:波片的快轴方向误差控制在±2°内,位相延迟误差不大于λ/300时,Mueller矩阵的最大测量误差为0.040 2,波片自身误差对测量结果的影响可以忽略不计;波片自身误差所引起的方位角误差不大于0.16rad时,快轴方向误差引起的椭率角误差最大不超过0.032 rad,位相延迟误差导致的椭率角误差小于0.015 rad,且对偏振度无影响.     

Accurate and fast speed measurement using ramp-waveform samplingtechnique

A novel “ramp-waveform sampling technique” for accurate and fast speed measurement is presented. Square pulses from an encoder are turned into ramps using analog electronics. They are then sampled, and linear regression is used on ramp-waveform sample points to extrapolate backward and determine the starting point of each pulse very accurately     

Synthesis of silicon dioxide film using high-concentration ozone and evaluation of the film quality

We investigated the ozone oxidation characteristics on a hydrogen-terminated Si substrate. A high-concentration ozone gas generator with an ozone condensation unit was specially designed and assembled for this study. During the oxidation by ozone with the concentration of 25 vol.% in the temperature range from 340°C to 625°C at 8 Torr (1.1 kPa), the formed oxide film thickness increased with oxidation time in accordance with the parabolic law, which suggests a diffusion-controlled step, while the oxidation by pure oxygen attained saturated states within 3 min of initiating oxidation. The activation energy for parabolic constants in the ozone oxidation was determined to be 0.52 eV. This value is much smaller than the activation energy for dry oxidation with oxygen, while it is almost the same as that in the plasma oxidation with the mixture of rare gas and oxygen. Moreover, the quality of the ozone oxidation film was evaluated by estimating the amount of suboxides (Si³⁺+Si²⁺+Si⁺) using x-ray photoelectron spectroscopy (XPS) analysis and the compressive stress using Fourier transform infrared (FT-IR) spectroscopic analysis. Both results showed that the quality of film subjected to ozone oxidation at 500°C is equal or superior to that of the film subjected to pyrogenic oxidation at 750°C in spite of the faster oxidation rate, and thus, the significant advantages of ozone oxidation at low oxidation temperatures could be confirmed.     

Characterization of oxide etching and wafer cleaning using vapor phase anhydrous hydrofluoric acid and ozone

A cleaning process using anhydrous hydrofluoric acid/methanol (AHF) and ozone was carried out in a vapor phase cleaning module (VPC). The dependence of the AHF vapor phase etch rate of thermally grown silicon dioxide on different process parameters, such as etch time, AHF-flow and temperature was studied. The optimized etch process is attained at a temperature of 40°C and a pressure of 50 mbar. To demonstrate the feasibility of this cluster tool for advanced gate dielectric formation, investigations on surface properties after AHF vapor cleaning, such as contact angle measurement and atomic force microscopy (AFM) were carried out. Using XPS, the surface binding states of HF-vapor treated silicon surfaces were studied. Traces of fluorine and low oxygen coverage were monitored. An ozone treatment immediately after AHF cleaning increases significantly the fluorine concentration on the silicon surface. A beneficial impact of AHF and ozone on the electrical characteristics of 4 nm oxide films grown in oxygen by RTP in a cluster tool immediately after cleaning without breaking the vacuum was found.     

温度应变双参量同时测量的光纤传感技术研究

光纤光栅用于传感领域存在应变和温度的交叉敏感问题。从温度与应变的分离方法方面主要分双波长矩阵法和双参量矩阵法两类,综述了用于温度和应变同时测量的光纤光栅传感器的最新研究成果,对一些基于其他理论的新方法也做了简要的介绍。概括了各方法的基本原理,并对这些方案的优点和不足进行了分析。     

Optical wavefront measurement and/or modification using integratedoptics

Sensors consisting of an array of interferometers to measure phase differences and straight waveguides to measure intensity along an optical wavefront have been fabricated in LiNbO₃ at four wavelengths, λ=0.458, 0.514, 0.82, and 3.39 μm, and the performance of the sensors has been evaluated. The outputs of the arrays are coupled to an imaging CCD and fed into a computer. Calculations are presented for a conceptual design of a scanning one-dimensional array producing a 50×50 pixel snapshot. Experimental results are presented for 20-resolution-element one-dimensional interferometer arrays at 0.514, 0.82, and 3.39 μm. The results indicate that accurate modification of wavefronts as well as measurements of wavefronts are possible. Two structures for modification of optical wavefronts are proposed