随机电磁光束经像散透镜后磁场的光谱Stokes奇点  

Magnetic spectral Stokes singularities of stochastic electromagnetic beams through an astigmatic lens

作　　者：郑尚彬 唐碧华 姜云海 高曾辉[2] 罗亚梅[1,2] 

机构地区：[1]西南医科大学医学信息与工程学院,泸州646000 [2]宜宾学院,计算物理重点实验室,宜宾644000

出　　处：《物理学报》2016年第23期114-121,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61275203,61505075);四川省教育厅自然科学基金(批准号:15CZ0017)资助的课题~~

摘　　要：利用交叉谱密度函数的传输公式,以部分相干刃型位错光束为例,推导出随机电磁光束磁场通过像散透镜传输后的解析表达式.使用光谱Stokes参数,详细讨论了光谱Stokes场的奇点变化规律.结果表明,随机电磁光束磁场通过透镜后的传输过程中,存在光谱s12,s23和s31奇点.改变刃型位错的离轴量、斜率、空间相关长度等光束参数以及随着传输距离的变化,会有磁场光谱Stokes奇点的移动、产生和湮没,也会有V点的产生和C点旋向性的反转.此外,还与电场的光谱Stokes奇点做了比较.Much interest has been aroused in the polarization singularities. A new technique for metrology called singular Stokes polarimetry based on the detection of polarization singularities has been recently developed and used to detect deformations and displacements of samples on a submicron scale, to measure the topology of polarized speckle field and to study the biomedicine as well. The polarization singularities have been extensively studied theoretically, numerically and experimentally. However, most of the studiesare restricted within the frameworks of the fully coherent wave-fields.By using the spectral Stokes parameters introduced by Korotkova and Wolf [Korotkova O, Wolf E 2005 Opt. Lett. 30198], Yan and Lü [Yan H, Lü B 2009 Opt. Lett. 34 1933] have extended the concept of the polarization singularities from fully coherent beams to partially coherent beams. On the other hand, Hajnal [Hajnal J V 1990 Proc. R. Soc.Lond. A 430 413] studied the electric and magnetic polarization singularities in free-space propagation experimentally with microwaves and confirmed that the electric and magnetic polarization singularities are not coincident in general.In this paper, taking the partially coherent edge dislocation beam for example, the explicit magnetic propagation expression for stochastic electromagnetic beam through an astigmatic lens is derived based on the representation of cross-spectral density matrix propagation. Using the spectral Stokes parameters the magnetic spectral singularities are studied in detail. It is shown that there exist magnetic spectral s12, s23 and s31singularities of stochastic electromagnetic beams through an astigmatic lens. The magnetic spectral Stokes singularities correspond to the zero points of complex Stokes fields sij= 0. s12 singularity corresponds to the circular polarization（C-point） of partially coherent beam, and s3 0（s3 0） means right-（left-） handedness, where the orientations of the major and minor axes of the polarization ellipse become undefined. s23 and s31sin

关 键 词：随机电磁光束 像散透镜 磁场光谱Stokes奇点 

分 类 号：O441[理学—电磁学]