用于波分复用的双层氮化硅垂直光栅耦合器的仿真分析

Simulation Analysis of Double-Layer Si_(3)N_(4) Vertical Grating Coupler for Wavelength Division Multiplexing

面向波分复用技术提出了一种双层Si_(3)N_(4)垂直光栅耦合器结构。基于时域有限差分(FDTD)方法对该结构模型(2D)进行了仿真及优化,重点研究了双层Si_(3)N_(4)的宽度、厚度、位置关系以及双层Si_(3)N_(4)结构距离光栅的高度对耦合效率的影响。结果表明,对于1550 nm波长的TE偏振入射光垂直入射,当光栅周期为579 nm,占空比为67.5%,加入厚度为60 nm的金属Al反射镜及双层Si_(3)N_(4)结构后,光栅耦合效率超过了94%。与未添加金属反射镜和双层Si_(3)N_(4)的垂直耦合光栅相比,耦合效率提高了约46%。

A vertical grating coupler structure for wavelength division multiplexing technology was proposed in this paper.Based on the finite-difference time-domain(FDTD)method,the structural model(2D)of vertical grating coupler was simulated and optimized.In order to improve coupling efficiency,the width,thickness and position of the double-layer Si_(3)N_(4) and the influence of the height of the double-layer Si_(3)N_(4) structure from the grating on the coupling efficiency were mainly studied.The results show that for the normal incidence of TE polarized incident light at 1550 nm wavelength,when the grating period is 579 nm,the duty cycle is 67.5%,and when the metal reflector with thickness of 60 nm and double-layer Si_(3)N_(4) structure are added,the grating coupling efficiency exceeds 94%.Compared with the vertical coupling grating without metal reflector and double-layer Si_(3)N_(4),its coupling efficiency is improved by about 46%.