亚波长介质膜光栅宽光谱消色差相位延迟器的研究

发布时间：2018-08-20 11:07

【摘要】：随着微加工工艺的发展和微光学应用领域的拓宽,微光学器件的特征尺寸不断缩小,亚波长光栅(SWG)应运而生,其偏振特性类似单轴晶体的双折射效应,这说明SWG将能够实现双折射材料具有的光学功能,可以用于多种偏振功能,如波片、偏振分束器和相位延迟器等。本论文主要以亚波长光栅的宽光谱消色差相位延迟器为研究对象,基于严格耦合波理论对光栅型的相位差和衍射效率(包括反射衍射效率和透射衍射效率)进行了分析,以90°的相位差为适应度评价函数,利用遗传算法的工具箱对光栅结构参数进行自动寻优,从而得到最优光栅结构参数,以实现高精度和高衍射效率的相位延迟器。本文主要开展的工作如下:首先分析亚波长光栅和介质膜光栅的衍射特性,对其理论分析过程进行了详细的阐述;其次针对相位延迟器中常用的1053 nm和1550nm两个中心波长,基于上述优化设计方法,设计了三种光栅结构实现宽光谱1/4波片消色差相位延迟,获得了以下研究结果:(1)以1550 nm为中心波长,采用单层光栅结构,实现了1350~1750 nm范围内,TE波和TM波的相位延迟量控制在90°±2°,衍射效率在80%以上,带宽可达到400 nm;(2)以1053 nm为中心波长,设计了夹层式的亚波长金属介质膜光栅结构,带宽为300 nm范围内相位延迟量在90°左右,最大偏差小于2.3%,且TE和TM波的衍射效率均高于90%;(3)以1053 nm为中心波长,设计了多层金属介质膜光栅(MMDG)的消色差相位延迟结构,优化后的相位延迟器在900~1200 nm范围内相位延迟最大偏差小于4.5%,且TE波和TM波的衍射效率均高于95%。所设计的三种光栅结构都有较大的工艺容差,性能上满足光学领域对相位延迟器的要求。
[Abstract]:With the development of microfabrication technology and the widening of the application field of micro-optics, the characteristic size of micro-optical devices is shrinking, and the sub-wavelength grating (SWG) emerges as the times require, and its polarization characteristic is similar to the birefringence effect of uniaxial crystals. This shows that SWG will be able to realize the optical functions of birefringent materials and can be used for many kinds of polarization functions such as wave plate polarization beam splitter and phase retarder. In this thesis, the phase difference and diffraction efficiency (including reflection diffraction efficiency and transmission diffraction efficiency) of the grating type are analyzed based on the rigorous coupling wave theory with the wide spectrum achromatic phase delayer of the subwavelength grating as the research object. With the phase difference of 90 掳as the fitness evaluation function, the structural parameters of the grating are automatically optimized by using the toolbox of genetic algorithm, and the optimal structure parameters of the grating are obtained to realize the phase delay with high precision and high diffraction efficiency. The main work of this paper is as follows: firstly, the diffraction characteristics of subwavelength grating and dielectric film grating are analyzed, and the theoretical analysis process is described in detail. Secondly, two central wavelengths, 1053 nm and 1550nm, which are commonly used in phase delay devices, are discussed in detail. Based on the above optimization design method, three kinds of grating structures are designed to realize the achromatic phase delay of 1 / 4 wave plate with wide spectrum. The following results are obtained: (1) the single-layer grating structure is adopted with 1550 nm as the center wavelength. The phase delay of te wave and TM wave is controlled at 90 掳卤2 掳, the diffraction efficiency is over 80%, and the bandwidth can reach 400nm. (2) taking 1053 nm as the center wavelength, the structure of interlayer subwavelength metal dielectric film grating is designed. The phase delay is about 90 掳, the maximum deviation is less than 2.3, and the diffraction efficiency of te and TM waves is higher than 90. (3) the achromatic phase delay structure of multilayer metal dielectric film grating (MMDG) is designed with 1053 nm as the center wavelength. The maximum deviation of phase delay of the optimized phase delayer is less than 4.5 in the range of 900 nm and 1200 nm, and the diffraction efficiency of te wave and TM wave are both higher than 95%. The three kinds of grating structures designed have large process tolerances and meet the requirements of the optical field for phase retarders.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN25

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