人工微结构介质的空间滤波特性及光束自旋分裂研究

发布时间：2018-05-25 01:20

本文选题：人工微结构介质 + 传输矩阵法　；参考：《湖南理工学院》2017年硕士论文

【摘要】：空间滤波器在电磁频谱中的图像增强、信息处理和激光科学领域都有着广泛的应用。近年来人工微结构介质被广泛研究,它可以人为的设计结构并呈现出超常的物理特性。针对传统空间滤波器存在的体积大、不能聚焦近场分量等不足,本文利用传输矩阵法等数值算法研究了人工微结构介质的空间滤波特性,探索即插即用(非聚焦型)的新型空间滤波器的设计,同时还研究了高斯光束中自旋分裂的调控规律,并取得了一定的研究成果:第一,提出了一种利用磁性材料来扩展绝对禁带的光子晶体结构,并探索研究了各结构参数对禁带宽度的影响。研究结果表明,合适地调节两种磁性材料的参数,增加两者波阻抗的差值,该光子晶体的绝对禁带宽度相应地增加;调节两种磁性材料的物理厚度,其绝对禁带中心也会随之调整;将两个一维磁性光子晶体组成异质结构,其第一禁带宽度与禁带中心之间的比值可达到1.41以上。第二,利用超常介质和准周期结构分别设计了小角度的低通空间滤波器,并探索了其相应的结构参数对其角域带宽的影响。研究发现利用超常介质设计得到的小角度低通空间滤波器是偏振无关的,角域带宽不受偏振态的影响;而利用准周期结构设计的小角度低通空间滤波器的角域带宽可以实现“粗调”和“精调”,更有可能应用于高功率激光系统中。第三,提出了一种新的波导模式控制方法,即将薄膜型空间滤波器嵌入到多模波导中。研究结果表明,只有当波导模式对应的模角在空间滤波器的角域带宽以内时,该波导模式才被允许通过滤波器。从而可以通过调节空间滤波器的角域带宽来选取所需要的波导模式,达到控制波导模式的目的。该方法相对简单、成本低、高阶模抑制效果好。最后,从理论和实验角度系统研究了利用动力学相位和几何相位对光自旋霍尔效应中的自旋分裂的操控。理论研究发现,几何相位控制着光束的自旋分裂大小和方向,而动力学相位操控着光束的整体平移。基于空间光调制器和超表面搭建了一套实验系统,该系统证明了基于动力学相位和几何相位操控光自旋霍尔效应中自旋分裂方法的可行性。
[Abstract]:Spatial filters are widely used in the fields of image enhancement, information processing and laser science. In recent years, artificial microstructural media has been widely studied. It can design artificial structures and exhibit extraordinary physical properties. In view of the disadvantages of the traditional spatial filter, such as the large volume and the inability to focus on the near-field components, the spatial filtering characteristics of artificial microstructured media are studied by using the transfer matrix method and other numerical algorithms. This paper explores the design of a new spatial filter with plug and play (non-focusing type). At the same time, the regulation of spin splitting in Gao Si beam is studied, and some research results are obtained: first, A photonic crystal structure using magnetic materials to extend the absolute band gap is proposed and the influence of structural parameters on the band gap is investigated. The results show that the absolute band gap of the photonic crystal increases correspondingly by adjusting the parameters of the two kinds of magnetic materials and increasing the difference between the two impedance values, and the physical thickness of the two kinds of magnetic materials is adjusted. The ratio between the first band gap width and the band gap center of the heterostructure formed by two one-dimensional magnetic photonic crystals is above 1.41. Secondly, the low-pass space filter with small angle is designed by using supernormal medium and quasi-periodic structure, and the influence of the corresponding structure parameters on its angular bandwidth is explored. It is found that the small angle low-pass space filter designed by using the supernormal medium is polarization independent and the angular bandwidth is not affected by the polarization state. The angular bandwidth of the low-pass space filter with small angle designed with quasi-periodic structure can realize "coarse tuning" and "fine tuning", which is more likely to be used in high-power laser systems. Thirdly, a new waveguide mode control method is proposed, in which the thin-film spatial filter is embedded into the multimode waveguide. The results show that the waveguide mode is allowed to pass through the filter only if the corresponding mode angle of the waveguide mode is within the angular bandwidth of the spatial filter. Thus, the desired waveguide mode can be selected by adjusting the angular bandwidth of the spatial filter, and the waveguide mode can be controlled. This method is relatively simple, low cost and good high order mode suppression effect. Finally, the manipulation of spin splitting in the optical spin Hall effect by using the dynamic phase and the geometric phase is studied theoretically and experimentally. It is found that the geometric phase controls the spin-splitting size and direction of the beam, while the dynamic phase controls the overall translation of the beam. An experimental system based on spatial light modulator and supersurface is constructed. The system proves the feasibility of the spin splitting method based on dynamic phase and geometric phase to manipulate the spin Hall effect.
【学位授予单位】：湖南理工学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713

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