受激布里渊散射光纤陀螺中光偏振特性的研究

从Jones矩阵理论出发 ,利用统计平均的方法 ,导出在受激布里渊散射光纤陀螺 (SBS FOG)敏感环中保偏光纤熔接点处偏振主轴进行θ角旋转后 ,传输光的偏振度P与光纤敏感环各参数之间的函数关系。在此基础上 ,进一步分析了光纤敏感环中传输光偏振本征态的特性 ,得出当L1=L2 ,θ =90°时在敏感环中的传输光不仅具有最大偏振度 ,而且还使其中的两个本征偏振态 (ESOP)达到稳定的结论     

SBS—FOG中受激布里渊散射光偏振特性的理论分析

本文考虑了双折射效应对保偏光纤两个偏振主轴方向上受激布里渊散射（SBS）光增益的影响,利用Jones矩阵理论分析了受激布里渊散射光纤陀螺（SBS－FOG）敏感环中在保偏光纤熔接点进行角的偏振主轴旋转后受激布里渊散射光的偏振特性,得出当θ=90度时,在敏感环中的受激布里渊散射光不仅具有最大偏振度,而且还使其中的两个本征偏振态（ESOP）达到稳定的结论。θ     

部分相干且部分偏振的光脉冲

提出了时域部分相干、部分偏振的光脉冲的慨念,定义了相应的时域部分相干-偏振矩阵(PCPM),对矩阵元和偏振度的测量方法以及光脉冲所满足的传输规律进行了研究;对矩阵元和偏振度的实验测量方法进行了分析．得到了光脉冲偏振度的表达式;进一步研究了部分偏振、部分相干光脉冲的传输和变换．发现在光脉冲传输过程中,矩阵元之间相互独立．并且各矩阵元的传输规律与标量的部分相干光脉冲一致。     

级联光纤环的空间全偏振态统计退偏特性研究

级联光纤环退偏器具有无源、经济、高效的特点,解决了当前发展较为成熟的Lyot型退偏器对窄带光退偏失败的缺点,是具有很大发展前景的新型退偏技术。研究了通过级联光纤环的不同循环传输路径实现光的空间分解,进而实现全偏振态退偏的统计特性。分解的各光分量由于通过不同的传输路径,其输出偏振态随机分布在所有偏振状态上。通过良好地设计光纤环长,可实现各分解光分量之间互不相干,从而实现合成输出光的统计退偏。实验实现了由10级光纤环级联实现的无需偏振控制的退偏器,对带宽为1.6nm的光源可以实现偏振度小于5%的稳定退偏光的输出。     

随机电磁光束在大气湍流中偏振态的变化

基于广义惠更斯-菲涅耳原理,以随机电磁双曲 正弦高斯(ShG)光束作为典型的随机电磁光束, 推导出随机电磁ShG光束在大气湍流中交叉谱密度矩阵元的解析表达式,并用以研究了随机 电磁ShG光束 在大气湍流中轴上偏振度、方位角和椭圆率的变化。结果表明,随机电磁ShG光束在大气湍 流中轴上偏振 度、方位角、椭圆率的变化与结构常数、Sh部分参数、空间相关长度和传输距离有关。随着 结构常数的减 小,或Sh部分参数的增大,方位角θ发生跃变位置增大,偏振度P达到最小值 和椭圆率ε达到最大值的传输 距离增大。当传输距离较远时,Sh部分参数Ω₀对偏振度P、 方位角θ和椭圆率ε的影响可以忽略。该研究工 作可为随机电磁光束在自由空间光通信中偏振态的分析提供理论基础和实验依据。     

耦合型微纳光纤偏振滤光器研究

微纳光纤偏振滤光器是光纤通信和传感系统的微型基本元件之一。利用超模耦合理论研究表明,当选择合适的耦合区长度和微纳光纤直径时,两平行紧贴微纳光纤构成的耦合器件可实现起偏效应,即将非偏振的输入光变为偏振光输出;理论设计分析给出了产生这种效应的几何参量值。实验研究了两根微纳光纤平行耦合时输出光偏振度(DOP)与耦合长度的关系,验证了起偏效应并制作了基于消逝场耦合的微纳光纤偏振滤光器。实验表明当微纳光纤偏振滤光器输入非偏振光时,在1545～1560nm波段耦合输出端光的偏振度达到了90%以上,实现了光束起偏;在此波段内某些波长的输出光消光比(LPER)可达到24dB以上,而其他波长处为椭圆偏振光或者圆偏振光,实现了分色起偏。此器件与检偏器组合可制成带通(阻)波长滤波器。     

半导体光纤环形激光器产生偏振混沌的数值研究

建立了半导体光纤环形激光器的动力学模型, 并进行了数值分析和研究。半导体光放大器采用由张应变引起的自身双折射理论模型, 光纤的双折射效应和偏振控制器对光的偏振调节作用综合用一个线性双折射琼斯矩阵表示。利用Matlab软件对该模型进行仿真, 寻找到特定电流下半导体光纤环形激光器产生偏振混沌时偏振控制器的延迟角与方位角的范围以及半导体光放大器注入电流对环形激光器产生偏振混沌的影响。仿真的环形激光器输出功率与偏振度随半导体光放大器注入电流的变化关系与实验结果相符。结果表明, 半导体光放大器注入电流越大、偏振控制器的延迟角与方位角越接近零, 越容易产生高频偏振混沌。     

SBS—FOG中克尔效应的理论分析

本文从理论上分析了受激布里渊散射光纤陀螺（SBS－FOG）中的克尔效应,得出附加的输出拍频与光纤敏感环中沿相反方向传输的泵浦光及受激布里渊散射光的不均匀性之间的函数关系,从而为在检测系统中抑制克尔效应提供了理论依据。     

基于双向二级喇曼抽运的偏振控制研究

为了发展具有实用价值的受激喇曼全光偏振控制方法,根据光纤中受激喇曼散射矢量理论和光纤随机双折射效应设计了基于双向二级喇曼抽运的全光偏振控制方案,构建了偏振吸引理论模型,采用严格数值迭代算法对该偏振控制方案进行了仿真分析,并完成了偏振控制方案最佳工作性能的优化设计。结果表明,当信号光波长为1550nm、功率为0.1mW、一级抽运光和二级抽运光的功率分别为1W和4W、其偏振态都为（0,1,0）、光纤长度为3km时,信号光偏振度可达0.85以上,且信号光强度波动低于35%。该方案有效降低了作用光波功率、减弱了信号光输出强度噪声,并提高了信号光输出偏振度。     

大芯径功率光纤中传输的激光束质量与偏振度研究

研究了在大芯径、多模功率光纤中传输的激光束光束质量和偏振与光纤长度的关系。用芯径为0．6mm的国产石英光纤及芯径为0．4mm和0．6mm的3M光纤做样品，实验结果表明输出光束的光束质量因子M^2值是光纤长度的双曲正切复合函数。线偏振光经光纤后其偏振度随光纤长度的变化呈指数衰减的关系。     

气溶胶散射光偏振度特性的理论研究

散射光偏振度在大气气溶胶、大气污染的遥感探测中有重要的应用价值。通过求解Mueller矩阵及偏振度,讨论了当激光器输出波长处于近红外波段806 nm时，散射介质的粒子数浓度对散射光偏振度的影响。给出了散射光的偏振度与散射介质的粒子数浓度之间的变化关系，为使用散射光偏振度研究大气遥感提供了新途径。     

Polarization properties of the flint glass fiber

To realize stable characteristics of a current sensor using the Faraday effect in an optical fiber, it is necessary to prevent the influence of birefringent effect on light passing the fiber, which is caused by photo-elastic effect and/or lack of axial symmetry of its structure. The flint glass fiber manufactured from flint glass with very small photo-elastic constant, which has circular core and satisfies the single ode condition,has been developed to solve this problem. This paper reports results of a study to clarify polarization properties of the fiber and to consider a method for highly stabilizing the polarization. From experiments to investigate the relationship between state of polarization of light inserted to the fiber and that emitted from another end, it was confirmed that the birefringence due to the photo-elastic effect and the lack of symmetry are negligibly small. It also became known that the azimuth angle of polarization of the emitted light depends on the shape of the curve of the fiber. Namely, a rotation of the polarization plane is equal to the amount of line integral of the torsional rate along the curve. A countermeasure is necessary for this phenomenon, because characteristics of the current sensor may be influenced if the flint glass fiber coil is deformed by environmental factors. From a consideration of the mechanism of the phenomenon, it is inferred that the problem can be solved by reciprocating light in the fiber to stabilize the polarization. The effect of this method is confirmed experimentally     

Theory of polarization evolution in interferometric fiber-opticdepolarized gyros

Single-mode (SM) fiber which is used in the sensing coil of depolarized interferometric fiber-optic gyroscopes (IFOG's) does not maintain the polarization state of light. As a consequence, the state of polarization evolves freely over the length of the sensing coil and over environment. The polarization evolution is induced by birefringence within the SM coil. Variations of this birefringence may lead to nonreciprocal errors whose treatment is presented in this paper together with signal fading and the mean wavelength stability. Thus, this treatment provides a relatively comprehensive analysis of polarization evolution in depolarized gyroscopes. The analysis leads to the conclusion that the depolarized gyro architecture with two depolarizers on the opposite sides of the gyro loop must be used to obtain low-drift behaviour     

Optical rotation sensing by the geometric effect of fiber-loop twisting

An optical technique for sensing a rotation angle is described and experimental results are presented. When a loop of an ideal fiber that exerts no linear birefringence is deformed into a nonplanar curve, the azimuth angle of linearly polarized light propagated in the fiber is rotated. The technique is based on this effect of geometric polarization rotation in an optical fiber. A twisted single-mode fiber is substituted for the ideal fiber. Experimental results include studies of polarization rotation and variations of light propagated in a loop of a twisted single-mode fiber under deformation.     

Analysis of the polarization characteristics of scattered light of underwater suspended particles based on Mie theory

Aiming at the problem of underwater polarized laser scattering caused by underwater suspended particles, the equivalent spherical particle Mie scattering theory simulation method is used to study the polarization characteristics of underwater scattered light. The relationship between underwater suspended particle characteristics and optical characteristics is analyzed, and the effects of particle size, polarization characteristics of incident light, and angle of incidence on the degree of polarization of forward and backward scattering light are studied. The results show that:When the incident light is natural light, the degree of polarization of scattered light is very low at the forward-scattering angle, which increases with the increase of the scattering angle, but changes frequently with the increase of the particle size. When the incident light is linearly polarized, the degree of linear polarization of the scattered light is related to the azimuth Angle. The degree of circular polarization is largely unaffected by particle size.     

受激布里渊散射光纤陀螺中光纤光源的阈值光功率研究

从非线性受激布里渊散射产生机理出发 ,研究了受激布里渊散射光纤陀螺 (SBS- FOG)中光纤光源的阈值光功率与光源谱宽及保偏光纤敏感环参数之间的函数关系 ,为进一步研究这种光纤光源的构造以及建立受激布里渊散射光纤陀螺系统打下了理论基础。     

高光谱多角度偏振信息反演盐水密度最佳波段

利用折射率可以建立偏振度与液体密度之间的函数关系.以不同浓度的盐水为例,通过USB2000光谱仪测得高光谱偏振信息并计算其密度,发现在不同入射角度计算不同浓度的盐水密度的最佳波段不同,在最佳波段范围内计算的盐水密度精度高.当入射角趋近布儒斯特角时最佳波段范围变宽,可以满足现今遥感技术的要求.该研究结果为遥感技术在监测水体密度方面提供了新的科学依据.