小型化全景系统的杂散光分析与抑制方法研究

由于全景环带光学系统的头部单元结构形式复杂，内部光路经过多次反射与折射，杂散光情况比较严重，因此全景环带光学系统设计过程中对杂散光的分析尤为重要。文中着重分析全景环带光学系统头部单元中产生杂散光的形式，对未经全景环带光学系统头部单元反射的杂散光建立消杂光数学模型，在此基础上对全景环带光学系统行了优化设计；对全景环带光学系统中头部单元胶合面反射的杂散光采用一种凸向像面的弯月胶合镜的形式进行抑制，并通过ASAP软件建模仿真。仿真结果显示，杂散光能量降低90%，证明采用的结构形式和消杂光数学模型有效地抑制了杂散光的产生。     

An approach to remove the background light based on linearly polarized light in the inter-satellite optical communications

In the inter-satellite optical communications, background light is an important factor that worsens the acquisition performance and tracking precision of the system. In general, optical filters are applied in eliminating background light. But the bandwidth of the optical filter is a bottleneck for improving the performance of the optical system further. We propose a new method for decreasing background light, in which linearly polarized light is employed as the beacon light. The theoretical model of acquisition probability is derived. Contrastive analysis is performed, among the system with the pure optical filter, the system using the linearly polarized light and the system with the circularly polarized light. Numerical simulations and experimental verification lead to the conclusion that acquisition probability of the system with linearly polarized light is greater than that of the other systems, and this approach is effective. This work can benefit the design of inter-satellite optical communication system.     

用于实现散射介质中时间反演的数字相位共轭的相干性

抑制散射介质对光的散射,调控光在散射介质中的传输,是光通信、生物光子学、光镊等领域的重要课题.设计并实现了基于宽谱光源和数字相位共轭的可调控光在散射介质中传输的时间反演实验系统.实验获取了不同相干长度下物光和参考光束之间的光程差与干涉图样、相位图及时间反演信号之间的关系,分析了光源相干性对调控光在散射介质中传输的影响.实验结果表明,基于宽谱光源的相干特性和数字相位共轭技术,通过调节光程差能选择性获取同一散射角度及相同传输路径的光束的相对相位,再利用空间光调制器对参考光束进行调控,实现光束的反向传播,从而选择性实现对同一散射角度及相同传输路径的光的时间反演.     

一次透镜封装的单片集成LED光源北大核心CSCD

在使用LED作为照明光源的过程中,光场作为LED应用中的关键因素,一般使用二次光学系统进行调控。但是二次光学系统一般设计复杂、体积大、重量重,随着LED光学封装系统朝着小型化方向发展,二次光学系统的应用将会变得困难。结合软件仿真和实验验证探索了用于单片集成发光二极管(MI-LED)的一次光学透镜的光场调控功能。研究结果表明,仿真和实验LED光源的光场几乎重合一致,所设计的一次透镜将LED光源的光束角从120°调控到48°~72°范围内。与未加一次透镜的LED光源相比,加一次透镜的LED光源具有更高的光提取效率和更均匀的空间光色分布。     

光纤陀螺信号处理中SLD驱动电路设计

光纤陀螺用光源要求输出功率高、相干性低、稳定性好，超辐射发光二极管（SLD）是能满足这些要求的理想光源，目前国内光纤陀螺用的光源基本上主要选择超辐射发光二极管（SLD），从工程实际应用出发，介绍了超辐射发光二极管（SLD）驱动电路设计，以此来提高光纤陀螺性能。     

Modeling and characterization of TFT-LCD display module for LED projector

We developed optical simulation models for TFT-LCD modules in LED projectors to study the effects of optical properties and light projection tilting angle on the transmission rate of liquid crystals. Optical properties for modules in each of the LCD panel layers were included in the study. The experiment for establishing crystal rotation was first constructed to measure changes in the transmission rate as light was projected on the LCD panel from different angles. The relationship between light attenuation and the allowable angles at which the LCD panel is able to allow light to shine through, was investigated. The results were used as parameters in the optical simulations. Through the use of LightTools, an optical software package, optical simulation was built for different modules in each of the LCD panel layers and optical simulation analysis was performed on the overall structure of the TFT-LCD panel. Results from the simulation analysis were compared with experimental results from scanning illumination measurement. The disparity between simulated and experimental values was less than 13%, ensuring the rationality and accuracy of the optical simulation.     

Optical Implementation of CMOS/SEED Optoelectronic Integrated Crossbar Interconnection Network

An optical implementation of CMOS/SEED optoelectronic integrated crossbar interconnection network is reported. The CMOS/SEED smart pixel arrays with O/E light windows are used as logical controlling switch nodes. High/lower modulating ratio of the output light density is about 1.4. The light beam is supplied by a 0.85 μm semiconductor laser diode. 8×2 spot arrays formed by a computer-generated phase grating are used as the pumping light beams for CMOS/SEED light modulators. High-precision 2-D optical fiber bundle arrays are used as the I/O access devices. 16×16 optical crossbar interconnection network is realized using our experimental setup. It is easy to couple with CMOS/SEED smart pixel arrays by using 2-D optical fiber bundle arrays as the I/O access devices. Compact in comparison with other optical interconnection systems.     

Optical Implementation of CMOS/SEED Optoelectronic Integrated Crossbar Interconnection Network

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二级级联式室内可见光通信光学接收天线设计

针对室内可见光通信系统的传统光学接收天线无法同时满足高增益和大视场的问题, 设计了一种二级级联式光学天线. 通过分析信噪比、通信速率与接收天线视场角的关系, 发现视场角为40°–60°的光学天线最适用于室内可见光通信系统. 通过光学仿真软件TracePro的模拟及计算, 给出了所设计的二级级联式光学天线的增益随信号光入射角的变化关系. 结果表明, 相较于传统接收天线, 二级级联式光学天线具有更好的光学性能, 视场角为菲涅耳透镜单独接收时的4 倍. 利用Matlab对二级级联式光学天线竖直向上时的接收功率分布进行仿真, 结果显示探测器接收到的信号功率提升效果明显, 平均值较直接探测时增大了7 dBm, 进一步证实该二级级联式光学天线适用于室内可见光通信系统.     

星载光学系统遮光罩消杂光结构优化设计方法

本文对星载光学系统遮光罩消杂光结构的优化设计做了初步探讨。提出了遮光罩和挡光环消杂光设计的基本原则．给出了一种二级遮光罩结构寸的优化设计方法和一种遮光罩内壁上挡光环位置优化设计方法，并对一级和二级遮光罩进行了初步的分析比较。     

星载光学系统遮光罩消杂光结构优化设计方法

本文对星载光学系统遮光罩消杂光结构的优化设计做了初步探讨。提出了遮光罩和挡光环消杂光设计的基本原则。给出了一种二级遮光罩结构寸的优化设计方法和一种遮光罩内壁上挡光环位置优化设计方法,并对一级和二级遮光罩进行了初步的分析比较。     

Pure spin photocurrents in low-dimensional structures

As is well known, the absorption of circularly polarized light in semiconductors results in optical orientation of electron spins and helicity-dependent electric photocurrent, and the absorption of linearly polarized light is accompanied by optical alignment of electron momenta. Here, we show that the absorption of unpolarized light leads to the generation of a pure spin current, although both the average electron spin and electric current vanish. We demonstrate this for direct interband and intersubband as well as indirect intraband (Drude-like) optical transitions in semiconductor quantum wells.     

Intensity modulated silver coated glass optical fiber refractive index sensor

Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback from environments, in which optical fibers act as a signal carrier. A novel Ag coated intensity modulated optical fiber sensor based on refractive index changes using IR and UV-Vis(UV-visible) light sources is proposed. The sensor with an IR light source has higher sensitivity compared to a UV-Vis source. When the refractive index is enhanced to 1.38, the normalized intensity of IR and UV-Vis light diminishes to 0.2 and 0.8, respectively.     

基于微机电系统红外光源的长光程气体检测

针对红外气体传感器对光源的要求,选用了一种宽波长、高调制频率、低功耗的小体积微机电系统(micro-electro-mechanic system, MEMS)红外光源作为辐射源,其各项性能均能很好的满足红外传感系统对于光源的要求。由于其面光源的朗伯辐射特性,整形之后的红外光数值孔径仍然很大,采用传统的长光程气室结构很难实现长光程从而提高系统的检测灵敏度。本文结合双波长单光路的差分检测方法,设计了一种基于积分球特性的吸收气室,有效地解决了MEMS红外光源在高灵敏度气体检测应用中难于实现长光程的问题;并运用光在传输过程中光通量守恒的原理,推导了此积分球吸收气室的等效光程,解决了积分球气室等效光程计算的难题;同时采用FPGA主控芯片对MEMS红外光源进行高频调制并处理探测器的输出信号,使得外围电路的设计更加简单、灵活。设计中,使用直径为5 cm的积分球吸收气室便可实现166.7 cm的等效光程,研究结果显示系统可测得的最小甲烷浓度达0.001×10-6,极大地提高了红外检测系统的灵敏度。     

纳米集成光路中的光源、光波导和光增强

使用近场光学显微术(scanning near-field optical microscopy, SNOM)研究了ZnO亚微米线端面出射性质,不同空间形貌Ⅱ-Ⅵ族半导体荧光器件光波导特性,二维光子晶体、准晶光子晶体对LED的出射增强作用以及表面等离激元(surface plasmon polariton, SPP)与半导体纳米荧光器件的相互作用,对纳米集成光路中的光源、光波导、光增强三个重要问题做了实验和理论上的分析.研究发现半导体微纳米线端面出射光束的质量与样品的直径有密切关系.通过合理地设计其直径和 关键词： 纳米集成光路 扫描近场光学显微术 光波导 光增强     

纳米集成光路中的光源、光波导和光增强

使用近场光学显微术(scanning near-field optical microscopy, SNOM)研究了ZnO亚微米线端面出射性质，不同空间形貌Ⅱ-Ⅵ族半导体荧光器件光波导特性，二维光子晶体、准晶光子晶体对LED的出射增强作用以及表面等离激元(surface plasmon polariton, SPP)与半导体纳米荧光器件的相互作用，对纳米集成光路中的光源、光波导、光增强三个重要问题做了实验和理论上的分析.研究发现半导体微纳米线端面出射光束的质量与样品的直径有密切关系.通过合理地设计其直径和     

基于传输矩阵法的聚合物太阳能电池光学性能分析

采用基于传输矩阵法的光学模型及Matlab软件,模拟了以聚合物P3HT:PCBM为活性层的倒装太阳能电池,并分析了模拟电池的吸光率及其内部光电场分布。探讨了厚度、入射角度以及新结构对电池光学性能的影响。模拟结果表明,电池的光吸收主要由活性层厚度决定,分别随着电子传输层和空穴传输层厚度的增加而下降。当光入射角度增大时,由于光程的增加电池的吸光率随之增加,在40°入射角时达到最大;由于其他光学作用,器件吸光率在40°入射角以后反而降低;证明了光斜入射时电场在整个器件中分布是不连续的。通过在基本结构的适当位置插入一层薄膜构成的微腔器件,由于光学共振效应能够有效提高电池的光吸收。     

基于白光LED照明光源的室内VLC系统

LED照明与可见光通信技术相结合,构建出基于LED可见光无线通信系统。对室内VLC(Visible Light Communication)系统的白光LED光源特性和系统信道模型分析,提出照明光源布局设计与接收光功率分布的关系;对强度调制直接检测方式的室内VLC系统中信噪比和多径效应引起的码间串扰分析,提出采用光分集接收技术克服码间串扰和提高信噪比,并给出光检测器阵列布局的模型。建立VLC系统仿真模型,给出OOK-NRZ (On-Off Keying & Non-Return Zero)和OOK-RZ(On-Off Keying & Return Zero)调制方式的误码率和均方根时延扩展之间的关系曲线。仿真结果表明,接收光功率相同时,均方根时延扩展时间大于1.0 ns时,OOK-RZ特性优于OOK-NRZ。     

分散橙25掺杂的聚合物PMMA薄膜全光极化的研究

制备了以分散橙25为客体的掺杂型有机聚合物PMMA薄膜样品，对之进行了全光极化研究，极化使薄膜产生诱导二阶非线性光学效应，种子光的强度越大，其二阶非线性极化率达到的饱和值越大;种子光的位相差、相对强度比、光场强度等因素影响薄膜的二阶非线性的优劣.     

Optical coherent detection Brillouin distributed optical fiber sensor based on orthogonal polarization diversity reception

In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fiber sensor is achieved.