高衍射效率偏振无关合束光栅的双层梯形槽形设计与分析  

Design and analysis of a double-layer trapezoidal groove of polarization-independent beam-combining gratings with high diffraction efficiency

作　　者：孙澳 王瑞鹏 孙雨琦 王新宇 李文昊[1] 姜岩秀 SUN Ao;WANG Rui-Peng;SUN Yu-Qi;WANG Xin-Yu;LI Wen-Hao;JIANG Yan-Xiu(Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院长春光学精密机械与物理研究所,吉林长春130033 [2]中国科学院大学,北京100049

出　　处：《中国光学(中英文)》2025年第1期53-62,共10页Chinese Optics

基　　金：国家重点研发计划(No.2023YFF0715802);国家自然科学基金青年基金(No.12105288,No.U21A20509);中国科学院青年创新促进会项目(No.2022218);吉林省自然科学基金项目(No.20210101139JC)。

摘　　要：为了满足强激光系统对于合束光栅的宽带、高衍射效率及偏振无关的需求,本文提出了一种具有双层梯形结构的偏振无关合束光栅。首先,基于严格耦合波理论,建立了一种以粒子群优化算法为核心的偏振无关合束光栅设计模型,通过随机生成特征波长实现效率特性寻优。然后,详细分析了单层梯形和双层梯形结构光栅的槽深、占宽比、侧壁倾角等结构参数对光栅衍射效率及带宽的影响。最后,对两种结构光栅的电场增强特性进行分析讨论。结果表明,双层梯形结构偏振无关合束光栅在51 nm(1038~1089 nm)带宽范围内实现99%以上的理论衍射效率,相比传统单层梯形结构具有更大的工艺容差,容差范围内均满足30 nm带宽和98%的高衍射效率,同时具有更低的光栅近场增强,可以拥有更强的抗激光损伤能力。本文提出的宽带高衍射效率双层梯形结构光栅可以提高激光系统的输出功率,在激光合束领域具有重大的应用价值。In order to meet the needs of broad band,high diffraction efficiency,and polarization independence,a double-layer trapezoidal polarization-independent beam grating is proposed in this paper.Firstly,based on the strict coupled wave theory,a design model of polarization-independent combined beam grating based on a particle swarm optimization algorithm is established,and the efficiency characteristics are optimized by randomly generating characteristic wavelengths.Then,the effects of slot depth,width ratio,side angle,and other structural parameters on the diffraction efficiency and bandwidth of single-layer and doublelayer trapezoidal grating are analyzed in detail.Finally,the electric field enhancement characteristics of the two structures are analyzed and discussed.The results show that the polarization independent beam combining grating with double-layer trapezoidal groove achieves a theoretical diffraction efficiency of more than 99%in the bandwidth range of 51 nm(1038 nm−1089 nm),and has a larger process tolerance than the traditional single-layer trapezoidal structure,which meets the bandwidth of 30 nm and the high diffraction efficiency of 98%in the tolerance range,and has lower near-field grating enhancement.It has a stronger resistance to laser damage.The proposed double-layer trapezoidal grating with wide band and high diffraction efficiency can improve the output power of laser systems,and has significant application value in the field of laser beam combination.

关 键 词：衍射光栅 偏振无关 工艺容差 电场 

分 类 号：TP394.1[自动化与计算机技术—计算机应用技术] TH691.9[自动化与计算机技术—计算机科学与技术]