光纤参数测试

以白光迈克尔逊干涉仪对双折射保偏光纤的偏振藕合进行测试,并基于仪器结构建立了测试扫描结果的数学模型。分析及仿真了信噪比对藕合强度及祸合位置检测的影响大小及变化趋势。信噪比     

基于小波降噪的偏振耦合检测分析

理论分析了基于白光干涉的保偏光纤偏振模式耦合检测原理,并以迈克尔逊干涉仪对保偏光纤的偏振耦合的耦合强度和耦合点的位置进行了测试.由于机械式扫描干涉仪和信号处理电路会受到环境干扰和各种噪声的影响,限制了系统偏振耦合检测的灵敏度,应用小波变换对检测信号进行了分析,采用软阈值方法降噪处理,有效地去除了各种干扰和噪声,提高了干...     

新型偏振干涉成像光谱仪信噪比研究

基于辐射度学、电磁与偏振理论和傅里叶变换光谱学理论，从理论和实验上对超小型稳态偏振干涉成像光谱仪的信噪比进行了深入地分析与讨论.推导出了其信噪比的理论计算公式；采用计算机模拟给出了傍轴条件下信噪比随入射角的变化规律；深入分析了偏振干涉成像光谱仪所特有的偏振化方向对信噪比的影响.在调制度等于0.6，0.7，0.8，0.9，1.0时，给出信噪比随偏振器光轴偏角的变化关系，并给出最优化值.在最优化情况下，采用计算机模拟得出了信噪比随探测器像元数的变化规律，与干涉成像光谱实验结果完全相符.理论与实验结果表明，该偏振干涉成像光谱仪在高调制度的情况下具有高通量、高信噪比的显著特点，适合于航空航天、远距离目标和微弱信号的探测.该研究为新型偏振干涉成像光谱技术的研究和新型成像光谱仪的设计、研制和工程化提供了重要的理论依据和实践指导.     

光的偏振对热光关联成像的影响

根据完全偏振光的不同偏振态和部分偏振光的不同偏振度对二阶关联函数的影响,利用统计光学理论研究了光的不同偏振性质对关联成像的可见度和信噪比的影响.研究表明,光的偏振对热光关联成像的影响体现在部分偏振光的不同偏振度上,关联成像的可见度是偏振度的二次函数,由二阶关联函数方法得到的信噪比随着偏振度增大而提高,而利用减去背景项的二阶关联函数以及二阶相干度方法得到的信噪比均与偏振度无关. 关键词： 关联成像 偏振 可见度 信噪比     

大气湍流对空间目标偏振成像探测的影响

为研究大气湍流对空间目标偏振成像探测准确度的影响,构建了大气湍流影响下的偏振成像探测模型,并对大气湍流导致的空间目标偏振度探测偏差进行仿真分析.通过对分时和同时偏振成像方式进行仿真,发现大气湍流会对空间目标偏振成像探测准确度造成明显影响,且对分时偏振成像探测准确度的影响明显大于同时偏振成像方式.通过自适应系统校正部分低阶像差,能明显减小大气湍流对偏振成像探测准确度的影响.为了兼顾图像信噪比和大气湍流影响下的偏振成像探测准确度,给出了一种结合分时和同时成像方式的改进偏振成像探测方式,大气湍流对其的影响略大于同时偏振成像方式,但该方式图像信噪比明显优于同时偏振成像方法.另外仿真分析发现,采用多帧图像叠加能效减小大气湍流带来的空间目标偏振成像探测偏差,在使用分时偏振成像方式时效果尤为明显.     

单模光纤耦合器的偏振温度特性研究

理论分析并研究了温度变化对单模光纤耦合器的偏振特性的影响.推导了单模光纤耦合器输出消光比与输入消光比、模式耦合率的关系表达式.利用多个偏振特性不同的光源,进行了在快速温度变化条件下单模耦合器输出消光比随温度变化的测试实验,证明了采用低偏振的光源有利于降低单模耦合器中因温度变化引起的模式耦合效应.最后仿真计算了在光源输出消光比不同的情况下模式耦合引起的光纤陀螺输出误差的大小,为不同环境应用的光纤陀螺选取合适的光源提供了参考.     

双强度调制静态傅里叶变换偏振成像光谱系统测量原理及仿真

为了抑制背景噪声,获得高信噪比的纯干涉条纹并实现图像、光谱和全偏振信息的同时测量,提出了一种基于双强度调制的静态傅里叶变换偏振成像光谱技术新方案.系统由前置望远系统、两个相位延迟器构成的偏振来谱调制模块、Wollaston棱镜构成的偏振.分束器、Savart偏光镜和线偏振器构成的干涉糢块以及CCD面阵探测器组成,可在单一探测器上同时获取两幅经过不同强度调制的全偏振干涉图,通过对两幅全偏振干涉图的简单加减运算,便可获得探测目标清晰的纯图像和高信噪比的纯干涉条纹.对该系统的图像和光谱偏振复原过程进行了理论分析和数值摸拟,结果表明该系统可有效分离探测目标的背景图像和干涉图像,实现高精度的光谱复原和全偏振信息的有效提取,具有髙稳定性、高光谱、高灵敏度、高信噪比、信息复原精度高及数据处理复杂度低等优点,为偏振干涉成像光谱技术的发展提供了新思路.     

亚波长刻槽结构衍射场研究与数值计算

用耦合波理论分析考虑了亚波长刻槽结构有限刻槽光栅对光波场的衍射作用,给出了TE偏振以及TM偏振入射下的耦合波方程,并通过数值计算给出了单槽及多槽在TE偏振正入射下的衍射场分布. 关键词：     

双环掺铒光纤激光器混沌偏振控制方法研究

提出双环掺铒光纤激光器激光混沌的偏振耦合控制以及部分偏振控制方法,偏振耦合控制能控制耦合相互作用以控制激光混沌,部分偏振控制是控制部分偏振耦合效应以控制激光混沌.数值模拟了偏振耦合控制混沌和某一个环的部分偏振控制混沌,它们都能实现把双环掺铒光纤激光器激光混沌控制到稳定态和周期态上;通过实时调控光的偏振方向,这两种混沌控制方法都能实时地、动态地、有效地控制激光混沌进入到稳定态和周期态上.     

偏振复用通信系统中偏振模耦合产生的啁啾

研究了相互垂直的两个偏振模耦合产生的啁啾.利用耦合非线性薛定谔方程推导出两垂直偏振耦合模产生啁啾的表达式,分析了偏振模走离效应和入纤功率分配对啁啾的影响.研究结果表明:较弱的走离效应对啁啾影响较大,当走离效应参量超过某一值时啁啾趋于零;随着偏振角的改变,啁啾也随着改变,不再互成镜象.     

Polarization Control with Piezoelectric and LiNbO3 Transducers

Several Polarization control transducers have appeared on the market, and now automated, endless polarization control systems using these transducers are becoming available. Unfortunately it is not entirely clear what benchmark performance tests a polarization control system must pass, and the polarization disturbances a system must handle are open to some debate. We present quantitative measurements of realistic polarization disturbances and two benchmark tests we have successfully used to evaluate the performance of an automated, endless polarization control system. We use these tests to compare the performance of a system using piezoelectric transducers to that of a system using LiNbO3 transducers.     

Polarization Control with Piezoelectric and LiNbO3 Transducers

Several Polarization control transducers have appeared on the market, and now automated, endless polarization control systems using these transducers are becoming available. Unfortunately it is not entirely clear what benchmark performance tests a polarization control system must pass, and the polarization disturbances a system must handle are open to some debate. We present quantitative measurements of realistic polarization disturbances and two benchmark tests we have successfully used to evaluate the performance of an automated, endless polarization control system. We use these tests to compare the performance of a system using piezoelectric transducers to that of a system using LiNbO3 transducers.     

A compact, low loss and polarization insensitive fiber-optic gyroscope transceiver module configuration based on free-optic integration

A compact, low loss and polarization insensitive transceiver module configuration based on free-space integration which is applicable to a high sensitive and miniature fiber-optic gyroscope is proposed. The basic idea of this module is to construct a double power output configuration so that both of the powers of the two split orthogonal polarized components of the source propagating along different paths can be utilized fully which thus improves the signal-to-noise (SNR). In addition, the signal intensity received by the detector is insensitive to the source polarization and is independent of the power ratio of the two split orthogonal polarized beams, which relaxes the polarization specification of source and simplifies the integration processes of transceiver module.     

倾斜光纤光栅谱特性

基于倾斜光纤光栅耦合模理论,采用数值分析法研究了前后向导模耦合时倾斜角度和调制深度对倾斜光纤光栅反射谱的影响,以及导模和辐射模耦合时针对不同的入射光偏振态在倾斜角度、调制深度、光栅长度等不同时倾斜光纤光栅透射谱(或反射谱)的特性.研究结果表明,在前后向导模耦合时,不同偏振态入射光的光谱几乎相同;而对于辐射模耦合,由于反射谱的包络受消光系数的调制,而不同偏振态入射光的消光系数不同,并且倾斜角度越大不同偏振态的入射光的消光系数差别越大,故在研究辐射模耦合时需要将偏振态予以考虑.     

倾斜光纤光栅谱特性

基于倾斜光纤光栅耦合模理论,采用数值分析法研究了前后向导模耦合时倾斜角度和调制深度对倾斜光纤光栅反射谱的影响,以及导模和辐射模耦合时针对不同的入射光偏振态在倾斜角度、调制深度、光栅长度等不同时倾斜光纤光栅透射谱(或反射谱)的特性.研究结果表明,在前后向导模耦合时,不同偏振态入射光的光谱几乎相同;而对于辐射模耦合,由于反射谱的包络受消光系数的调制,而不同偏振态入射光的消光系数不同,并且倾斜角度越大不同偏振态的入射光的消光系数差别越大,故在研究辐射模耦合时需要将偏振态予以考虑.     

All-optical regeneration of polarization division multiplexing signals in polarization nonlinear loop mirror

All-optical regeneration of 2 × 10-Gb/s RZ-OOK polarization-division-multiplexed (PDM) signals is demonstrated through a single polarization nonlinear loop mirror configuration. PDM signals with orthogonal polarization states are regenerated simultaneously and reassembled automatically. Up to 3.0-dB eye-diagram-based signal-to-noise-ratio (SNR) improvement is achieved for both channels with the input SNR of 6.7 dB. Such scheme is also capable of mitigating the polarization-mode-dispersion (PMD) effect for PDM signals in the presence of up to 6.3-ps DGD.     

Polarization enhancement technique for nuclear quadrupole resonance detection

We demonstrate a dramatic increase in the signal-to-noise ratio (SNR) of a nuclear quadrupole resonance (NQR) signal by using a polarization enhancement technique. By first applying a static magnetic field to pre-polarize one spin subsystem of a material, and then allowing that net polarization to be transferred to the quadrupole subsystem, we increased the SNR of a sample of ammonium nitrate by one-order of magnitude.     

Combined effect of PMD and PDL on four-wave-mixing-induced crosstalk in WDM system

We derive an explicit autocorrelation function (ACF) formula of state of polarization for a fiber transmission system with polarization mode dispersion (PMD) and polarization dependent loss (PDL), which is found to agree well with Monte Carlo simulation. Then we use the new ACF to investigate the combined effect of PMD and PDL on the polarization multiplexed scheme. We find the performance of the polarization multiplexed scheme can be deteriorated more severely than the case without PDL.     

Dual-band plasmon induced transparency controlled by the polarization of the incident wave

In this paper, a hybridized plasmonic waveguide system is investigated numerically. By coupling plasmonic modes with different waveguide modes, two plasmon induced transparency (PIT) windows with high transmittance and deep modulation can be realized. Through the polarization of the incident wave, the transparency windows can be dynamically controlled.