矢量光束空间偏振编码的研究

矢量光束独特的空间偏振结构使之应用于空间偏振编码成为可能。提出了一种用一阶矢量光束的偏振分布进行极角空间编码的方法。通过矢量光束生成、光束偏振分布再调制实现了空间编码光束的生成,并采用斯托克斯参数法对空间编码光束进行检测。实验结果证实了一阶矢量光束应用于极角空间偏振编码的可行性,为基于空间偏振编码的激光驾束制导提供了新方法。     

一种基于新型偏振干涉成像光谱仪的目标偏振信息探测新方法

提出了一种采用基于视场补偿型Savart偏光镜的新型偏振干涉成像光谱仪对二维目标偏振信息进行空间遥感探测的新原理和新方法.在新型偏振干涉成像光谱仪光学系统不变的情况下,通过旋转偏振干涉仪分别测出了三个不同角度下像面上各像点的光强值,反演出了二维面目标的斯托克斯矢量,并给出了各像点偏振度和偏振方向的理论表达式.采用计算机模拟实验对该探测原理和方法进行了验证,所得结果与理论完全符合.从理论和实践上扩展了干涉成像光谱仪的探测功能,与目前国内外所研究的成像光谱仪相比,该成像光谱仪既能同时探测目标二维空间信息和一维光谱信息,又提供了一种获得目标偏振信息的手段和方法.     

Analysis of polarization conversion in AlGaAs/GaAs electrooptic polarization converter

A numerical simulation study of the polarization conversion phenomenon in deeply etched semiconductor electrooptic polarization converter is presented. Based on a powerful and versatile finite element method, the effects of various parameters on the polarization conversion in electrooptic semiconductor polarization converter are reported.     

Analysis and comparison of four anhysteretic polarization models for lead magnesium niobate

Four anhysteretic polarization models that have been used in the literature to evaluate data acquired from lead magnesium niobate (PMN) are analyzed and compared. Derivations of two of the models from assumed spatial distributions of dipole energy states, using first physical principles, are presented. A third model is derived from a suitable integral averaging calculation. These derivations are used as the basis for developing an integral equation for determining an energy-state distribution that produces a fourth model, which was not originally formulated in terms of an assumed distribution. A new polarization function is also presented. Excellent approximations to each of the four polarization functions of interest can be deduced from this new polarization function by adjusting the numerical value of just a single parameter. An application of two of the models to data is presented. It is shown that it can be necessary to consider a sample to be an admixture of two distinct species of poles, in the sense that two polarization functions must be added together in order to accommodate the data.     

新型偏振干涉成像光谱仪中格兰-泰勒棱镜像质分析与评价

阐述了自行研制的新型偏振干涉成像光谱仪中重要偏光器件格兰-泰勒棱镜的分光机理,应用光线追迹法分析计算了光在格兰-泰勒棱镜中的传播规律与光线轨迹;推导出了任意角度入射时光线在棱镜中的传播方向及出射点坐标;给出了格兰-泰勒棱镜的像点位移和色差理论计算公式.该研究对晶体器件像质的分析计算及评价具有普遍的指导意义,为新型偏振干涉成像光谱技术的研究以及偏振干涉成像光谱仪的研制提供了重要的理论依据. 关键词： 偏振干涉成像光谱仪 格兰-泰勒棱镜 像点位移 色差     

Double-pass self-spectral-calibration of a polarization state analyzer

We present a new method that allows efficient spectral calibration for a polarization state analyzer. The procedure does not require any additional polarization optical element other than the polarization state analyzer itself. It uses a double-pass technique that can be achieved up to a very good precision. The method is illustrated using real measurements done at several wavelengths with a rotating wave plate polarization state analyzer. Alignment of axis as well as true retardation at a specific wavelength are easily obtained by a standard function fitting.     

Quadrature phase-shifting interferometer with a polarization imaging camera

We present a new high-speed phase distribution measurement, in which a polarization imaging camera is applied to a quadrature phase-shifting interferometer. The polarization imaging camera composed of a polarizer-mask on a detector array can provide simultaneously two phase-shifted data in quadrature. Two sets of two phase-shifted data in quadrature are obtained before and after a change of the interferometer such as object displacement or environmental disturbances. Phase sum and difference distributions of the interferograms between two states with arbitrary phase-shift in the interferometer are calculated with the two sets of two phase-shifted data in quadrature. This phase calculation method in the pixel displaced phase-shift method has such advantage that phase-shifted data required for the calculation of phase distributions can be obtained by only two pixels in the polarizer-mask detector array, which means no reduction of the image resolution in the other direction. The principle of this technique and experimental results are presented.     

Anomalies of polarization processes in relaxor ferroelectrics

The anomalous polarization of relaxor ferroelectrics (relaxors), such as solid solutions of barium-strontium niobate (SBN) and lead magnesium niobate (PMN), is studied in ac low-frequency (up to 10^?4 Hz) and dc electric fields. The results of studying dielectric hysteresis loops, polarization relaxation, the coercive-field distribution spectrum, nonlinear polarization for various scales of inhomogeneities, and polarization in a photosensitive SBN relaxor subjected to illumination are presented. All of the anomalous polarization properties of relaxors substantially distinguish them from ordinary homogeneous ferroelectrics and serve as signs and a measure of structural disorder. This article presents a brief review of our recent studies and some new results obtained as a result of their analysis.     

Improved measurement of polarization state in terahertz polarization spectroscopy

A calibration scheme is presented for improved polarization state measurement of terahertz pulses. In this scheme the polarization response of a two-contact terahertz photoconductive detector is accurately measured, and is used to correct for the impact of the nonidealities of the detector. Experimental results show excellent subdegree angular accuracy and at least 60% error reduction with this scheme.     

偏振风成像干涉仪多波长探测理论研究

简述了偏振风成像干涉仪(PAMI)探测高层大气风场的基本原理;研究得出了多波长探测时偏振风成像干涉仪干涉强度、仪器调制度与位相延迟片的延迟位相之间的理论表达式;得出了偏振风成像干涉仪的干涉强度和仪器调制度受所探测谱线波长调制的重要结论;采用计算机模拟分析了使用偏振风成像干涉仪(设计谱线为高层大气氧原子跃迁时辐射的630nm的极光谱线)探测高层大气时各目标谱线的干涉强度和仪器调制度,给出了干涉强度和仪器调制度与探测谱线波长之间的关系,得出了732nm的极光谱线不适合用作探测目标的结论. 本文为高层大气风场探 关键词： 高层大气风场探测 偏振风成像干涉仪 调制度 多波长探测     

汉折射波片用于发散光束的偏振像差分析

本文利用光线追迹法,对双折射波片用于发散光束的偏振像差进行了分析,并以标准1/4波片为例,给出了小角入射时的近似处理方法.     

Design of optical polarization splitters in a single-section deeply etched MMI waveguide

The design of a single-section polarization splitter in a deeply etched semiconductor MMI waveguide is presented. Numerically simulated results indicate that the semiconductor MMI exhibits considerable polarization dependence and, utilizing this effect, a compact 1.6-mm-long polarization splitter may be fabricated to yield more than 8-dB polarization separation and only 0.11-dB optical loss, using a very simple design-approach. Received: 16 May 2001 / Revised version: 14 August 2001 / Published online: 2 November 2001     

Instantaneous coherent polarization and coherent polarimetric spectra

The statistics of polarization in electromagnetic waves or target vector has been studied deeply, generally using Stokes parameters. Unfortunately, all the data-processing includes the assumption that the sampling data are independent of time, without a consideration of the time coherence of the polarization data, such as instantaneous Stokes parameters. In this paper, the definitions of the instantaneous coherent polarization function and polarimetric spectrum are presented for the first time, which shows the coherences of the instantaneous Stokes parameters in both time and frequency domain, even in spatial coherence. The new formula of definition can be extended to spatial propagation coherence, both in free space or any linear medium.     

Skew aberration: a form of polarization aberration

We define a new class of aberration, skew aberration, which is a component of polarization aberration. Skew aberration is an intrinsic rotation of polarization states due to the geometric transformation of local coordinates, independent of coatings and interface polarization. Skew aberration in a radially symmetric system has the form of a circular retardance tilt plus coma aberration. Skew aberration causes undesired polarization distribution in the exit pupil. We demonstrate statistics on skew aberration of 2383 optical systems described in Code V's U.S. patent library [Code V Version 10.3 (Synopsys, 2011), pp. 22-24]; the mean skew aberration is 0.89° and the standard deviation is 1.37°. The maximum skew aberration found is 17.45° and the minimum is -11.33°. U.S. patent 2,896,506, which has ±7.01° of skew aberration, is analyzed in detail. Skew aberration should be of concern in microlithography optics and other high NA and large field of view optical systems.     

Independent control over the amplitude,phase, and polarization of femtosecond pulses

We introduce a shaper setup which takes advantage of laser pulses passing through a spatial light modulator twice, thereby effectively utilizing a four-liquid crystal mask configuration. This approach grants control not only over the phase and polarization but also the amplitude. The Jones vector of the light wave after passing through the setup is considered in detail including polarization sensitive grating efficiency. A new method of counteracting the polarization dependent grating transmission is described and a comparison between the desired and recorded pulses is presented. PACS 42.25.Ja; 42.15.Eq; 42.65.Re     

Generation of azimuthally and radially polarized beams by coherent polarization beam combination

A new architecture for generating pure azimuthally and radially polarized beams is presented. It involves coherent polarization beam combination of two orthogonally polarized LP(11) fiber modes. Experimental results reveal that high purely polarized (polarization purity of 95% or better) azimuthal and radial beams can be generated.     

Identification of excited states in Na2 by two-step polarization labeling

In two-step polarization labeling, as in polarization labeling, a polarized pump laser is tuned to a molecular transition. This produces an optical anisotropy in the upper and lower levels of the pump transition. A linearly polarized probe laser will experience a change in polarization when it interacts with these oriented levels of the molecule. Probe delays of several nanoseconds distinguish lower level depolarization from upper level depolarization. The technique has been applied to Na₂ to identify three new excited states. Preliminary values of some of the molecular constants are presented.     

偏分复用系统中偏振模色散补偿与偏分解复用一体化方案

本文建立了偏分复用系统中偏振模色散与信号偏振态变化引起信道串扰的数学模型, 分析了偏振模色散对偏分复用信道射频功率的影响, 并提出了适用于偏分复用系统的光域偏振模色散补偿与偏分解复用同时进行的方案: 用信道的射频功率作为反馈控制信号, 监测链路中偏振模色散和偏振态变化引起的信道串扰的大小, 用改进的粒子群优化算法对偏振控制器进行自适应控制, 同时完成偏振模色散补偿与偏分解复用. 在112 Gb/s偏分复用-差分正交相移键控(PDM-DQPSK)传输系统中仿真验证了该方案的有效性. 结果表明该方案可以使112 Gb/s-PDM-DQPSK传输系统完成自适应偏分解复用的同时, 在1 dB的光信噪比代价下, 使系统对偏振模色散的容忍度提高20 ps. 关键词： 偏分复用系统 信道串扰 偏振模色散 偏分解复用     

Photon polarization tensor in a magnetized plasma system

We investigate the photon polarization tensor at finite temperatures in the presence of a static and homogeneous external magnetic field. In our scheme, the summing of the Matsubara frequency is performed after Poisson resummation, which is easily completed and converges quickly. Moreover, the behaviors of finite Landau levels are presented explicitly. It shows a convergence while summing infinite Landau levels. Consequently, there is no necessity to truncate the Landau level in a numerical estimation. At zero temperature, the lowest Landau level (LLL) approximation is analytically satisfied for the vacuum photon polarization tensor. However, we examine that the LLL approximation is not enough for the thermal polarization tensor. The thermal tensor obtains non-trivial contributions from the finite-n Landau levels. And, photon spectra gains a large imaginary contribution in thermal medium, which is the so-called Landau damping. Finally, it is argued that the summation of Matsubara frequency is not commuted with Landau level ones, such conjecture is excluded in our calculations.     

Complex degree of mutual polarization

Starting from the concepts of coherence and polarization, we generalize the conventional degree of polarization, introducing a two-point parameter, the complex degree of mutual polarization V, which is defined in terms of measurable quantities. We demonstrate the physical significance of this new quantity for the case of fully correlated, pure states of polarization at the two points, showing that the magnitude of V is a measure of the similarity between the states of polarization at two different points in space.