BaO-TiO_2-SiO_2系统微晶玻璃窗口的制作及光学性质

讨论了以ＢａＯＴｉＯ２ＳｉＯ２系统作为基础玻璃组分烧制的散射型微晶玻璃窗口的部分光学性质。这种窗口在激光测量中的使用，可退偏振降低探测器的偏振效应误差，提高探测器的抗光损伤能力。针对不同的情况，可扩大探测器的线性动态范围一至两个数量级。     

中波红外集成偏振光栅结构参数对偏振性能影响仿真分析

中红外集成偏振焦平面探测技术将偏振探测技术与中波红外焦平面成像探测技术融合,通过异质集成的方式实现偏振光栅和探测器的单片集成,具有体积小、质量轻,机械稳定性高等优势,可实现多偏振方向的同时成像。像元级的亚波长金属光栅可实现不同偏振方向的高消光比,然而金属材料的选择、光栅的周期、占空比、厚度等参数均会影响偏振探测器的偏振性能。给出了亚波长金属光栅的理论分析,建立了中波红外集成偏振HgCdTe探测器的偏振性能仿真模型,对不同光栅参数对探测器偏振性能影响进行了仿真分析,确定了Al光栅周期200~400 nm,占空比0.5~0.7,厚度＞100 nm的参数选择。仿真分析得到在±14°入射角范围内,偏振消光比变化较小。同时,引入了Si基HgCdTe探测器,仿真分析了SiO₂增透膜厚度对偏振消光比的影响,确定了SiO₂最佳厚度在500 nm附近,对Si基和CdZnTe衬底集成偏振HgCdTe探测器的消光比进行比对,得出了Si基探测器偏振性能更优。仿真结果可为中波红外集成偏振HgCdTe探测器偏振光栅的设计提供理论指导和参考。     

片上红外偏振探测研究进展

偏振是光的固有自由度,偏振探测提供了光强和波长之外的更多丰富信息。红外偏振探测器在成像、通信、遥感和宇宙学等众多应用中发挥着至关重要的作用。然而,传统的偏振检测系统体积庞大、系统复杂,阻碍了偏振探测的小型化和集成化。近来,片上红外偏振探测器的发展引起了广泛的研究兴趣。本文将重点介绍片上红外偏振探测器的两个前沿研究领域：偏振敏感材料和偏振选择性光耦合结构集成的红外偏振探测器,主要讨论片上红外偏振探测器的研究现状以及未来的挑战和机遇。     

InGaAs短波红外探测器的偏振响应特性分析

在偏振成像和激光功率测量技术领域,凡涉及偏振光的定量测量,都会由于光束的偏振态对探测器的影响而产生显著的误差.这种现象主要是由于许多类型的光探测器存在偏振敏感响应引起的.本文对光电探测器的偏振响应进行了分析,推导了光电探测器偏振相关损耗的斯托克斯模型.分析了SiNx钝化膜对InGaAs探测器偏振响应的影响.结果表明,无SiNx钝化膜时,随着入射角度的增加,偏振响应损耗明显增加,而随着波长的增加,偏振响应损耗明显降低;采用SiNx钝化膜时,随着波长的增加,偏振响应损耗先减小后增加.由于设计的SiNx薄膜的增透中心波长为1550nm,1310nm波长处的偏振响应损耗大于1550nm处的偏振响应损耗.     

InGaAs探测器偏振响应特性的实验研究

分析了光电探测器偏振响应产生的原因,定义了探测器偏振敏感度的公式,制备了测试用InGaAs探测器.为了测试器件的偏振敏感度,搭建了测试系统,并对器件的偏振敏感特性进行了测试.结果表明,测试系统具有较好的稳定性;器件响应存在明显的偏振特性,正人射时器件的偏振敏感响应为0.27 dB,斜人射时器件偏振敏感有所增加,人射角度...     

基于Bang-Bang和PID复合控制的红外探测器温控系统设计

红外探测器作为星载偏振探测载荷的核心部件,用于实现短波红外波段辐射偏振信息的光电转换。为保证应用性能,需要对探测器进行精密温控,保证其工作在较低且稳定的温度以降低探测器热噪声和暗电流。本文介绍了一种红外探测器温控系统,采用FPGA控制完成温度信号的采集并输出控制信号,数模转换器控制三极管驱动电流完成半导体制冷器的驱动,采用Bang-Bang和PID复合控制算法完成探测器的精密温控,测试结果表明,温控精度优于±0.1℃,温度稳定时间小于6 min,可将探测器在较短的时间内控制在目标温度范围内,为实现短波红外波段的高精度偏振信息测量提供保障。     

基于谐振波导光栅的偏振选择广角光探测器(英文)

高性能偏振选择型光探测器是偏振检测系统中不可或缺的一部分。提出了一种由硅基谐振波导光栅和InP/InGaAs PIN光探测器混合集成的光探测器结构。利用严格耦合波分析方法设计了硅基谐振波导光栅结构,利用时域有限差分法优化了该混合集成光探测器的结构参数。数值仿真结果表明该光探测器在宽带范围内具有高量子效率、较大入射角容差及偏振选择性。该器件可以应用于偏振敏感系统中。     

中波碲镉汞红外偏振焦平面探测器的制备研究（特邀）

针对隐身等多类高价值目标精确探测与识别以及探测技术持续发展需求,为实现复杂战场环境下的高概率真假目标识别和高精度目标检测、定位、跟踪,开展复杂战场环境下隐身及微弱特征目标探测及抗干扰探测等技术研究意义重大,其中高集成度的焦平面型偏振红外探测器技术是其中一个重要方向。围绕集成式中波（MW）256×256碲镉汞红外偏振焦平面探测器的研制,介绍了偏振结构的设计、制备到偏振探测器的集成,以及偏振探测器性能的测试等方面的研究进展状况,设计加工出了亚波长金属光栅阵列,采用倒装互连的方式实现了偏振探测器的集成,并在MW 256×256碲镉汞焦平面器件上实现了红外偏振性能的测试和评估。     

光电探测器表面损伤状态偏振成像式探测系统

针对在外场实现探测器损伤状态实时探测的需求,研发了光电探测器表面损伤状态偏振成像式探测系统。理论推导了“猫眼”目标回波偏振特性参数DP和回波偏振度DOP的表达式,利用MATLAB软件仿真绘制了表面粗糙度、回波偏振度以及偏振特性的关系曲线;设计了一套同时偏振成像光学系统,开展了671 nm连续激光对电荷耦合器件（CCD）表面损伤状态的实时探测外场实验,编制了基于MATLAB GUI的回波图像可视化实时采集系统,得到了回波图像强度、偏振特性以及光斑尺寸等信息;通过光学显微镜和白光干涉仪对探测器表面损伤处和未损伤处形貌图像分析,发现探测器损伤表面可见硅基底且粗糙度参数Sq值较大;结果表明,仿真结果与实验测试结果具有良好一致性。光电探测器被损伤后,其表面粗糙度增大,回波偏振特性参数DP减小,退偏特性明显,偏振度DOP减小。偏振成像技术可有效对光电探测器表面损伤状态进行实时探测,该研究提供了一种外场条件下实时探测的好方法。     

红外偏振探测器融合成像研究

分析了红外偏振探测器对于探测识别红外伪装目标以及红外暗弱目标的重要应用意义。详细介绍了物体的红外偏振特性及其表示方法,并阐述了红外偏振特性的影响因素。最后重点介绍了偏振成像融合算法。步骤分为数据预处理、红外偏振融合和融合图像再处理。本文对研究红外偏振探测器融合成像具有重要意义。     

回旋管输出窗频率特性的研究

本文对回旋管输出窗系统的传输特性进行了理论研究,给出了圆波导径向突变的模式散射的近似公式,研究了输出窗对工作模式的反射和寄生模式的散射的频率响应。实验证实分析是合理的。     

结构保持的双边滤波极化SAR图像降噪

针对极化合成孔径雷达(Polarimetric Synthetic Aperture Radar, PolSAR)图像相干斑抑制时结构保持的难题,该文提出一种PolSAR图像的双边滤波算法:结构保持的双边滤波(SPBF)。该算法通过结合边缘结构特征和地物散射特性,增强对PolSAR图像结构信息的描述,减少滤波时图像结构信息的损失,实现滤波性能的提高。该算法首先使用边缘检测模板在极化总功率图像(Span)上提取边缘方向,实现自适应选择滤波方向窗;其次,采用Freeman-Durden分解获取像素的散射机制,并根据极化数据的统计分布特性获取地物散射的聚类标记;最终在所选的方向窗中,以聚类标记图为掩膜,利用改进的双边滤波算法对PolSAR数据进行相干斑抑制。真实SAR数据的实验结果表明,该方法能够有效抑制相干斑噪声,同时提高了对图像的边缘、强点目标和极化散射特性的保持能力。     

On the resonant scattering at guide dielectric windows

The effect of output wave resonant scattering at vacuum window of a microwave device caused by high-quality dielectric window eigenmodes excitation is studied. These negative resonant effects can seriously influence the device operation. The numerical calculation results are confirmed by a model experiment.     

高透明Al2O3陶瓷窗口

本文所介绍的高透明Ａｌ_２Ｏ_３窗口兼有以往许多种光电探测器窗口的优点：比如有极好的机械强度和硬度；较宽的光谱透射区域１９０－７０００ｎｍ；较高的总透射率（＞９０％）；优良的散射退偏振特性。并且因其具有适度的散射功能及与晶体Ａｌ_２Ｏ_３相似的透明波段，当它被用作激光探测器窗口时，可使激光较均匀地分布于探测表面，起到大幅度地提高探测器的抗激光损伤能力，同时降低探测元的非线性响应引起的测量误差的作用。     

无源双极化标签式雷达目标及其应用

提出了一种用于雷达目标检测的L型无源双极化标签式雷达目标结构,研究了该标签的雷达散射特性,讨论了标签式雷达目标在机动车交通管制系统中的应用。利用L型金属结构的表面感应电流分布特性提高雷达目标的交叉极化散射特性,将雷达标签置于实际尺寸的机动车模型前窗之上,仿真并比较了机动车贴装雷达标签前后的雷达散射截面。分析表明:这种雷达标签对提高雷达对机动车辆的探测和识别能力实际有效,研究结果对于构建经济实用的机动车交通管制系统具有实际意义。     

A Unified Approach to the Analysis of a Category of H-Plane Discontinuities

Based on the mode matching method, the generalized scattering parameters including the fundamental and higher order modes (multi-modes) are obtained for the discontinuity interface of a category of waveguide H-plane discontinuities. Then by using a general port-connection order-decrease method raised by the author, the whole discontinuity including the two interfaces and the intermediate part of finite length or zero length (as is the case for very thin inductive windows or irises) can be combined into one network, and the generalized scattering parameters of this network can be obtained from which the scattering parameters of the fundamental mode can be extracted. If needed, the equivalent circuit parameters can be calculated directly from the scattering parameters. Examples are given to show the validity and versatility of this new method for dielectric filled waveguide, inductive iris and/or window, E-plane metal and/or finline insert, and even the offset E-plane finline insert, etc.. Multiple inserts, windows and irises can also be analysed.     

On the optimization of the aspect angle windows for the Doppler analysis of the radar return of rotating targets

Optimum resolution in the Doppler spectra of rotating targets is obtained by using an optimum aspect angle window from which the data for the Fourier transforms are taken. The width of the optimum aspect angle window depends on the location, relative to the axis of rotation, of the scattering center to be resolved, so that for optimum resolution a sort of focusing by choosing the appropriate aspect angle window is necessary. Formulae and graphs for optimum width of aspect angle windows and the obtainable resolutions are given. Typical applications of the scheme presented are in the experimental determination of the location, the strength, and the interaction of the scattering centers on a target. These in turn are of major interest, e.g., for the analysis and synthesis of radar cross sections, in glint investigations, and in target imaging.     

Diffuse channel model and experimental results for array antennasin mobile environments

A wide-band spatial model of the mobile channel has been developed. The model allows the inclusion of array antennas at the base station. The diffuse scattering is modeled using dense discrete scatterers. An algebraic power decay is used for the path loss to the scatterers of the environment and to the mobile. Results from the model are compared with experimental results obtained at 1800 MHz. The parameters that are used are delay spread, power window, and angular spread of incident power. The model elucidates the general diffuse background scattering in a rural and an urban environment. It can be extended with inclusion of spatial specular scatterers where appropriate     

Analysis of a Complete Gyrotron Oscillator Using the Scattering Matrix Description

Complete harmonic gyrotron oscillators in axial arrangement including cavity, uptapers, collector waveguide and output window have been numerically simulated using a scattering matrix resonator code. The output mode purity and the influence of window reflections on the performance of a step-tunable, very high frequency gyrotron, Gyrotron FU IV A, at Fukui University was analyzed.     

An Accurate Transient Analysis of High-Speed Package Interconnects Using Convolution Technique

An accurate transient analysis of a package interconnect requires the modeling and analysis of conductor and dielectric losses, as well as other high-frequency effects of 3D structures. The skin effect and dispersion of interconnects are more accurately modeled in frequency domain. Consequently, an accurate time-domain simulation of such a system is only possible using convolution techniques. Although the convolution method is well understood, the application of windowing for frequency-dependent interconnect analysis is less so. In this paper, we present the practical considerations of window selection and its application to improve the accuracy of convolution simulators. We introduce the Tukey window and study the tradeoff between how smoothly data can be set to zero to avoid aliasing and suppress ripples and how much information tapering will discount at the edge of the window in order to obtain meaningful results. The bandlimiting effects of the Tukey window and other well-known windows are also compared. Finally, to verify the validity and accuracy of the proposed method, a wirebond PBGA package and a PCB-connector system are analyzed using the scattering parameters obtained from simulation and measurement, respectively.