投影光学系统中的偏振像差分析

当光束斜入射时,光学薄膜存在一定的偏振效应。在飞利浦棱镜系统中,当一定大小孔径角的照明光束斜入射到分色合色薄膜后,S偏振分量和P偏振分量存在一定的相位差,使得线偏振光变成椭圆偏振光。利用琼斯矩阵偏振光线追迹的方法,分析了投影光学系统中由于两偏振分量相位差引起的偏振像差,以及它与暗态泄漏光强和系统衬比度的关系。得出了系统出瞳面上的光波偏振特性,以及在不同大小孔径角的照明光束入射下偏振像差的变化。分析了膜厚监控误差对光学系统偏振像差的影响,发现膜厚监控误差对偏振像差和系统衬比度有很大的影响。所使用的分析方法可以应用于其他大口径光学系统。     

关于部分偏振光能量传递和偏振态的光线椭圆分析方法

部分偏振光传播时的光强和偏振态变化情况比较复杂, 尤其是当大数值孔径成像时, 光束的偏振态还会影响成像质量. 本文提出一种用于分析部分偏振光能量传递和偏振态的光线椭圆方法, 采用光线椭圆叠加的办法来分析光束在各向同性的均匀介质中传输时能量和偏振态的变化情况, 同时直观性好, 计算量小. 论文最后, 对大数值孔径、 高像质的齐明透镜系统讨论了入射无偏振光的能量、 偏振态变化, 以及偏振效应问题. 结果表明, 大数值孔径使成像光束中TM偏振光强度相对增加, 影响成像对比度; 提高像方介质的折射率, 会改善此种偏振效应问题.     

各向异性光子晶体的全反射隧穿偏振特性

为了研究一维各向异性光子晶体的全反射隧穿偏振特性,利用传输矩阵法计算了TE波和TM波以大于全反射角入射一维各向异性光子晶体时的透射率,在透射波中发现了TE波和TM波的一、二级全反射隧穿带.得出了与一维各向同性光子晶体的全反射隧穿效应的不同点,即TE波和TM波的一、二级全反射隧穿带的频率中心和频率宽度存在着较大的差异,利用这个特性可以将两种偏振光进行频率分离,为设计优质偏振滤波器提供理论依据.     

界面反射光的偏振态分析

首先利用菲涅尔反射公式,给出界面反射光s分量和p分量的光强反射率公式。然后分析并推导出自然光和部分偏振光分别入射介质界面时,反射形成的部分偏振光偏振度的一般表达式。对反射光偏振度的模拟分析表明,当自然光入射时,随入射角增加反射光的偏振度先增大后减小。当部分偏振光入射时,若I_sI_p,随入射角增加反射光的偏振度也是先增加后减小;若I_sI_p,则随入射角增加,反射光的偏振度呈现两次减小、两次增加。在正入射和掠入射的情况下,反射光的偏振度均与入射光的相同;在布儒斯特角入射的情况下,反射光的偏振度均为1,即线偏振光。最后,对线偏振光入射的情形进行了理论分析和模拟。结果表明,从光疏入射光密介质时,反射线偏振光的振动方位角随入射角增加单调增加。从光密入射光疏介质时,若入射角小于全反射临界角,反射线偏振光的振动方位角也随入射角增加而增加;若入射角大于全反射临界角,则随入射角增加,反射形成的椭圆偏振光的椭圆率先增大后减小。反射光偏振态的这些变化规律,对改造光的偏振态以及反射光偏振态信息的应用具有实际意义。     

拉盖尔-高斯光束在界面反射和折射的质心偏移特性研究

在圆柱坐标系中研究了傍轴线偏振拉盖尔-高斯光束在两种各向同性介质界面反射和折射后光强质心的偏移. 基于菲涅耳近似和泰勒级数展开,分别得到了部分反射和全反射两种情形下,质心的横向偏移和纵向偏移与光束拓扑荷的解析关系式. 研究表明,部分反射时,反射和折射光束的横向偏移的大小与光束的拓扑荷成正比,方向由拓扑荷的符号决定;而纵向偏移仅仅大小与光束的拓扑荷有关. 全反射时,反射光束质心偏移不受拓扑荷影响. 通过数值模拟验证了解析结果的正确性,并得到了解析公式的适用条件. 拉盖尔-高斯光束的质心偏移特性可应用于测量光 关键词： 拉盖尔-高斯光束 横向偏移 纵向偏移 拓扑荷     

基于金属狭缝阵列的各向异性偏振分束器

在金属-电介质结构的基础上提出了一种基于金属狭缝阵列的各向异性偏振分束器,并采用有限元法研究了横磁(TM)和横电(TE)偏振光入射后结构所表现出的负反射和镜面反射等特性.计算结果表明,当偏振光的入射角设定在20?—70?时,入射的TM光发生强烈的负反射,而TE光的负反射很弱,并随着波长的增加而急剧下降.分析可得偏振分束光栅的理想负反射点和反射面的完美对称响应效果.通过仿真得到了理想负反射点的取值范围.结合严格耦合波法软件,计算不同偏振光入射时负反射和镜面反射条件下的反射率,其消光比高达10~6.     

矢量光束界面反射透射的自旋霍耳效应

矢量光束的一般表示方法是利用投影矩阵和广义琼斯矢量的乘积描述.投影矩阵存在一个自由度,该自由度与有限光束的场矢量偏振状态有关,由特定的单位矢量与波矢量间的方位角决定,可以定量地描述矢量光束的偏振状态.本文在矢量光束描述的理论基础上,通过对投影矩阵进行与反射光束与透射光束传播方向相应的坐标旋转,根据麦克斯韦方程组及其边界条件,计算讨论在各向同性介质界面上反射、透射矢量光束的表示形式以及其自旋霍尔效应表现出的横向位移.线偏振光(光子自旋量为σ＝0)横向位移为零,圆偏振光束(光子自旋量为σ＝±1)位移量最大且左圆偏振与右圆偏振光束的位移大小相等方向相反,进一步分析了左圆偏振光束在界面上的反射、透射光束的横向位移与入射角的关系.     

涡旋光束在反射中的正交偏振特性研究

本文从角谱理论出发建立了涡旋光束在空气-玻璃界面反射时的傍轴传输模型, 并研究了反射过程中诱导产生的正交偏振效应. 当一水平偏振涡旋光束以不同角度入射时, 反射光束的正交偏振分量呈现出类似于一阶厄米-高斯模式的双峰强度分布, 而水平偏振分量强度分布呈现与入射光束相似的分布, 且只在布儒斯特角附近入射时才现出与正交偏振分量垂直的双峰分布. 对于任意线偏振入射光, 其正交偏振分量的偏振方向不再垂直于入射时的偏振方向, 而是与反射光束的中心波矢垂直, 此时正交偏振分量出现有趣的旋转特性, 其物理原因归结于任意线偏振光入射时所对应的水平与垂直偏振分量的反射系数不同. 最后进行了相关实验验证, 发现实验结果与理论分析符合得较好. 关键词： 正交偏振 涡旋光束 任意线偏振     

线偏振光在手征负折射介质中的古斯汉欣位移特性研究

从理论上分析了手征负折射介质中的横向位移特性,给出了线极化波入射条件下发生全反射时的横向位移随入射角的关系曲线。当入射角处于两个本征波的临界角之间时,TE和TM分量对应的横向位移方向相反。而当入射角大于全内反射角时,两个分量都将朝着正方向发生横向位移。通过比较发现手征负折射介质中的古斯汉欣位移特性与常规介质和一般手征介质也有着很大的不同之处。     

亚波长光栅偏振分束器的研究

利用单层亚波长硅光栅结构设计出工作在近红外波段的偏振分束器。该偏振分束器在45°入射角附近对TE偏振光具有很高的反射率同时对TM偏振光具有很高的透射率,其设计原理是基于亚波长光栅的泄漏模共振效应以及类布儒斯特效应。利用散射矩阵方法和时域有限差分方法对偏振分束器进行设计和分析。模拟结果显示,该偏振分束器在1390～1600nm的波长范围内的反射与透射消光比大于100;同时该偏振分束器具有相对较大的入射角度容差,在有限尺寸高斯光束入射下能保持很好的性能。     

Bessel beams: Effects of polarization

An approximation to a Bessel beam produced by tightly focusing linearly polarized light is known to produce a smaller central lobe than focusing plane polarized light. This is because the plane polarized wave gives a broad central lobe caused mainly by a parasitic longitudinal field component. It is known that this problem can be overcome by focusing radially polarized light. Here we demonstrate that other polarization distributions based on a linear combination of transverse electric (TE1) and transverse magnetic (TM1) fields can give a beam even narrower than for the radially polarized case. Special cases of this combination are identified, corresponding to the smallest width (TE1), and the maximum peak intensity compared with the side lobes (electric dipole polarization). Axially-symmetric forms can be generated by illumination with elliptically polarized light. A particular case is azimuthal polarization with a phase singularity, which is equivalent to TE1. For a semi-angular aperture of 60°, the TE1 case gives a central lobe width 9% narrower than for radially polarized illumination, while for plane polarized illumination it is 12% wider than the radially polarized case.     

光自旋霍尔效应中横移的影响因素研究

研究了光束在空气与电介质分界面传输产生的自旋霍尔效应,揭示了光束重心横移分别与偏振态、折射率差以及入射角三者之间的定性关系.研究发现各光场横移都随偏振参量增大而增大,左、右旋椭圆偏振光的横移等值反向,圆偏振态下的横移比椭圆偏振态下的横移大.改变折射率差的大小,反射光横移随折射率差的增大而减小,但当折射率差接近零时,反射...     

Spin Hall effect of light in one-dimensional photonic crystal

We established a general propagating model to investigate the spin Hall effect of light in one-dimensional photonic crystal. A polarized (spin dependent) Gaussian beam which was incident obliquely through one-dimensional photonic crystal was demonstrated. Having decomposed a polarized Gaussian beam into different plane wave components charactering individual wave vectors, we revealed the transmission coefficient and reflection coefficient of each plane wave which propagates through the one-dimensional photonic crystal. It enabled us to obtain exact solution to the electric field of transmitted and reflected beams, and the analytical formula of light intensity, accordingly. A method based upon the partial differentials with the intensity distribution of the transmitted and reflected Gaussian beams was presented to determine the transverse and longitude shifts explicitly. Spin dependent shifts in one-dimensional photonic crystal provide alternative evidence for the spin Hall effect of light.     

Optimization of focusing of linearly polarized light

We show that, by adding a π-phase shift to one-half of a linearly polarized beam, the roles of the transversal and longitudinal field components of the focused beam are interchanged, resulting in better focusing of the longitudinal component in the direction perpendicular to the phase jump line. For this component the scheme produces a spot with FWHM >15% smaller than a spot generated with either linearly or radially polarized light for any NA. The scheme has a similar advantage when applied to circularly polarized light, and it holds for both a plane wave and a realistic case of a Gaussian incident beam. This technique may find applications when using recording media responsive to the longitudinal field only, particularly in read/write for optical storage where the resolution in one transverse dimension is most important.     

光学马格努斯效应中的横向角移分析

从平面角谱理论出发,建立了光束在空气和玻璃界面折射的传输模型.基于这一模型,揭示了光学马格努斯效应中的横向角移现象.对于特定的线偏振和椭圆偏振光束,其折射场重心出现了横向角移,而当入射光束为圆偏振时,横向角移则会消失.在正负折射率界面,光束的横向角移产生了反转现象,这是由于光束在左手材料中发生了负衍射.超高折射率可明显地减少横向角移,而超低折射率则可显著地增强横向角移.这些发现将为如何调控和增强光学马格努斯效应提供理论依据. 关键词： 光学马格努斯效应 横向角移 圆偏振     

Reflection and transmission of Laguerre Gaussian beam from uniaxial anisotropic multilayered media

Based on angular spectrum expansion and 4 × 4 matrix theory, the reflection and transmission characteristics of a Laguerre Gaussian(LG) beam from uniaxial anisotropic multilayered media are studied. The reflected and transmitted beam fields of an LG beam are derived. In the case where the principal coordinates of the uniaxial anisotropic media coincide with the global coordinates, the reflected and transmitted beam intensities from a uniaxial anisotropic slab and three-layered media are numerically simulated. It is shown that the reflected intensity components of the incident beam, especially the TM polarized incident beam, are smaller than the transmitted intensity components. The distortion of the reflected intensity component is more evident than that of the transmitted intensity component. The distortion of intensity distribution is greatly affected by the dielectric tensor and the thickness of anisotropic media. We finally extend the application of the method to general anisotropic multilayered media.     

Resistive high-impedance surfaces (RHIS) as absorbers for oblique incidence electromagnetic waves

This paper presents a lightweight microwave absorber suitable for space applications. The absorber is based on a resistive high-impedance surface (RHIS) optimized to achieve reflection under ?15 dB in the band (2–2.3 GHz) at oblique incidence for transverse electric (TE) and transverse magnetic (TM) polarizations. A first classical isotropic RHIS structure is shown to be limited to angles of incidence up to 40° for TE polarized waves and up to 35° for TM polarized waves. So the objective of this contribution is to present a second solution based on an anisotropic RHIS structure which presents good absorption of incident waves in TE and TM polarizations for larger angles of incidence. An example is presented for an incidence angle of 65°.