用于全息波导的阶梯光栅设计  

Step Grating for Holographic Waveguide System

作　　者：袁烨 冯奇斌[2] 吕国强[3] YUAN Ye;FENG Qibin;LYU Guoqiang(AVIC Hua Dong Photoelectric Co.,Ltd.,Wuhu Anhui,241002,CHN;Academy of Photoelectric Technology,Hefei Udiversity of Technology,Hefei 230009,CHN;School of Instrumentation and Opto-electronics Engineering,Hefei University of Technology,Hefei 230009,CHN)

机构地区：[1]中航华东光电有限公司,安徽芜湖241002 [2]合肥工业大学光电技术研究院,合肥230009 [3]合肥工业大学仪器科学与光电工程学院,合肥230009

出　　处：《光电子技术》2020年第4期291-294,共4页Optoelectronic Technology

基　　金：安徽省科技重大专项(No.17030901053)。

摘　　要：基于标量理论计算了三阶任意宽度的台阶光栅的衍射效率,发现当台阶宽度相等时光栅的衍射效率最高。采用基于严格耦合波的仿真软件分析了不同折射率下阶梯光栅高度和衍射效率之间的关系。仿真结果表明:光栅材料的折射率分别为1.52和1.74时,达到最大衍射效率时光栅高度分别为700 nm和470 nm,当光栅高度偏离最佳高度100 nm时,衍射效率分别从60%降低到56%和59%降低到47%。采用无掩模直写光刻技术制备了设计的三阶光栅,实际测试了各级衍射效率和在波导系统中的显示效果。测试结果表明:-1级衍射效率达到49.7%,波导耦出端成像清晰。研究设计的阶梯光栅具有制备周期短、成本低、效率高的优点。Holographic waveguide could effectively decrease the weight and volume of a near-eye display system. As an important component,incouple/outcouple grating could heavily affect the final display brightness. The diffractive efficiency of a three-step grating with random duty cycle was firstly calculated and it was found that the grating with the same step width presented the highest diffractive efficiency. The simulations based on rigorous couple wave theory were exploited to analyze how grating height could affect diffractive efficiency in the case of different refractive indexes. The simulation results showed that when the refractive efficiency of the grating was 1.52 and 1.74,the grating height should be 700 nm and 470 nm to guarantee the highest diffractive efficiency. When the grating height was 100 nm less than the designed height,the diffractive efficiency decreased from 60% to 56% and from 59% to 47%,respectively. The designed grating was prepared by maskless direct-writing lithography. The measured-1 order diffractive efficiency could reach 49.7% and the output image could be clearly displayed at the end of the waveguide. The proposed three-step grating presents the merits of short preparation duty,low cost and high efficiency.

关 键 词：全息波导 光栅 衍射效率 无掩模光刻 

分 类 号：TN26[电子电信—物理电子学]