光偏振态的群论描述:转动矩阵的生成元

应用偏振光描述中的变换矩阵与群论的对应关系[1]和相应的计算理论,讨论了与偏振光学系统中的Jones矩阵、Mueller矩阵相对应的SU(2)群、SO(3)群和Lorentz群的生成元问题,给出了用单位矩阵、Pauli自旋矩阵和稀疏矩阵分别作为无耗偏振光学系统中SU(2)群元(Jones矩阵)和SO(3)群元(Mueller矩阵)生成元以及部分损耗偏振光学系统中的幺模群(Jones矩阵)和Lorentz群(Mueller矩阵)生成元的具体形式;矩阵计算理论说明这些群元的生成元表示可以简化偏振光学系统的计算。     

基于偏振成像技术的目标探测研究进展及分析

简述了利用偏振成像技术进行目标探测的物理特性,介绍了偏振成像技术的应用优点,概括分析了我国利用偏振成像技术进行目标探测的发展状况,指出了发展中存在的问题,叙述了国外在该研究方向所取得的主要成就。总结分析了基于偏振成像技术的目标探测的研究进展,并对其未来发展方向进行了展望。     

Quantitative Surface Chirality Detection with Sum Frequency Generation Vibrational Spectroscopy: Twin Polarization Angle Approach

介绍了一种新的表面和频振动光谱方法: 定量手性检测中的双偏振角方法. 一般来讲表面光谱信号中非手性项贡献最强,而纯界面手性信号要比非手性信号弱两到三个数量级. 因此在和频振动光定量测量和分析界面手性的贡献问题上存在困难. 在和频振动光谱的双偏振角方法中,通过固定入射红外光偏振方向,并同时改变入射可见光和初涉和频信号光的偏振角进行测量. 这样所得到的偏振依赖的和频振动光谱信号能够直接给出界面手性贡献的特征,并 且能够用于准确测量界面的手性和非手性贡献. 对双偏振角方法进行了描述,并且通过S和R手性的柠檬烯空     

衍射效应诱导涡旋光束的偏振度变化

基于惠更斯-菲涅耳衍射原理以及部分相干光的相干与偏振的统一理论,研究了衍射效应诱导部分相干涡旋光束的偏振度变化.通过理论分析与数值计算表明,部分相干涡旋光束经圆孔衍射后偏振度将发生变化,在衍射场中光束的偏振度分布情况与入射光束的相干度、入射光束的拓扑电荷数、衍射孔径的大小等因素有关.     

大气湍流对部分相干电磁平顶光束传输的影响

基于相干性和偏振性统一理论,采用Rytov相位结构函数平方近似推导出了部分相干电磁平顶光束在湍流大气中传输的偏振度、相干度和光谱强度公式,并研究了湍流对其传输特性的影响.研究表明,偏振度和相干度与源光谱的带宽无关.大气湍流使得不同阶数的部分相干电磁平顶光束的偏振度经长程传输后均趋于其初始值.大气湍流使得部分相干电磁平顶光束与电磁高斯一谢尔模型光束相干度的差别减小,并导致相干度的振荡和相位奇异现象消失.大气湍流使得相干性较好的部分相干电磁平顸光束的光谱跃变现象消失.     

KDP晶体折射率非均匀性检测系统

基于正交偏振干涉法,建立了KDP晶体折射率非均匀性的检测系统,并可实现晶体相位失谐角的间接检测.波前检测系统实现了测试光偏振态的精密控制与切换,采用波长调谐相移的方法去除了测试过程中参考面倾斜引入的误差,优化了抗振动相移算法,提高了波前测试的测量准确度及重复性.通过折射率非均匀性分析算法的设计,解决了晶体厚度变化引入的误差等.小口径晶体元件的测试结果表明系统的折射率非均匀性检测准确度(均方根值)优于10~(-6).     

Changes in the polarization, the coherence and the spectrum of partially coherent electromagnetic Hermite–Gaussian beams in turbulence

The unified theory of coherence and polarization is applied to an investigation of the changes in the polarization, the coherence and the spectrum of partially coherent electromagnetic Hermite–Gaussian (EHG) beams propagating through atmospheric turbulence. Based on the extended Huygens–Fresnel principle, the 2×2 electric cross-spectral density matrix of partially coherent EHG beams in turbulence is expressed analytically by using a quadratic approximation of Rytov's phase structure function. The analytical expressions for the degree of polarization, the degree of coherence and the spectrum of partially coherent EHG beams in turbulence are derived, and the corresponding analytical results of electromagnetic Gaussian Schell-model (EGSM) beams can be obtained when the order number of the Hermite polynomial is zero. Some interesting results are obtained, which are illustrated by using numerical examples.     

All-optical NRZ-OOK-to-RZ-OOK format conversions with tunable duty cycles using nonlinear polarization rotation of a semiconductor optical amplifier

We experimentally demonstrate an all-optical 10 Gb/s format conversion from non-return-to-zero (NRZ) on-off-keying (OOK) to return-to-zero (RZ)-OOK with tunable duty cycle in the whole C-band using nonlinear polarization rotation (NPR) arising in an semiconductor optical amplifier (SOA). The experimental results show that, by tuning the polarizer at the SOA output, an RZ signal with tunable duty cycle from 33% to 66% could be obtained with an extinction ratio(ER) over 10 dB. In addition, we show that the NRZ-to-RZ conversion with duty cycle of 33-66% can be obtained with less than 1 dB power penalty at the bit error ratio (BER) of 10⁻⁹. The device can facilitate the cross-connection between optical transmission networks employing different modulation formats.     

Complete chaotic synchronization mechanism of polarization mode of VCSEL with anisotropic optical feedback

We numerically investigate the complete chaotic synchronization mechanism of polarization mode of VCSEL with anisotropic optical feedback. Firstly, the synchronization quality of the x-linear polarization (LP) mode and the y-LP mode are both periodically changed with the angle θ between the polarizer and the light axes. Secondly, in a enough large scale region of the feedback coefficient and the injection current, where each LP mode can obtained good synchronization quality when the angle θ exists in the former half period region and the injection current is fixed at a certain value, which is over the threshold current. Under this condition, their synchronization quality is independent of the polarization states. By contrast, in the latter half period region of the angle θ where each LP mode can be obtained very instable and inferior synchronized quality. At last, the robustness of the synchronization scheme is sensitive to the internal and external parameter mismatch between the transmitter-VCSEL and the receiver-VCSEL.     

双轴晶体会聚偏光干涉的理论与实验研究

晶体会聚偏光干涉图包含了晶体特性的许多信息,建立偏光干涉图的定量分析方法可以使这些信息得到充分利用。基于双轴晶体折射时满足的波矢关系,导出了两折射光波相位差的精确计算公式。分析了光波在各界面折射时偏振态的变化,提出了会聚偏光干涉合成振幅的计算方法。针对任意取向的双轴晶体,计算了完整的偏光干涉图,反映了相位分布决定等色线、振幅分布决定消光影的规律。用数字图像模似了干涉图,并讨论了干涉图的变化情况。对4块不同取向的KTP晶片进行实验,实验干涉图与理论干涉图的特征完全一致,两者仔细对比可判断现有KTP晶体色散方程的优劣。