SOI基纳米光栅耦合器的结构改进与仿真验证

针对硅基光波导与单模光纤在光耦合过程中存在耦合效率低,对准难度大的问题,提出了一种新型基于绝缘体上硅(SOI)结构的纳米光栅耦合器。运用有限时域差分法探究了纳米光栅耦合器的结构特性,结合光纤准直器的准直原理,系统分析了纳米光栅耦合器的结构模型。研究了入射光波长、入射角度、光栅占空比等因素对光栅耦合效率的影响,得出了基本纳米光栅耦合器的最佳结构参数;在基本耦合光栅结构的基础上进行了改进,增加了后反射器、增透膜和底层介质膜,并运用Optiwave OptiFDTD 8.0软件优化了各部分结构的设计参数,得到了优化的耦合光栅结构。纳米光栅耦合器的耦合效率提高至59.37%,3dB带宽达到65nm。

Improvement and simulation model validation of nano-grating coupler based on SOI structure

A novel nano-grating coupler based on silicon-on-insulator structure is proposed to solve the mismatch issue between the silicon-based optical waveguide and the single-mode fiber. According to the principle of collimation, the structure model and characteristics of the nano-grating coupler are investigated by using the finite-difference time-domain method. Optiwave OptiFDTD 8.0 software is used to investigate the factors related to the coupling efficiency, such as the incident wavelength, the incident angle, the grating cycle, the grating duty ratio, the etching depth, the buried-oxide layer thickness and so on. Optimum parameters of the grating structure are obtained. The structure is optimized by adding the rear reflector, the antireflective film and the bottom dielectric reflector on the base of the basic grating. The maximum coupling efficiency of the grating coupler is up to 59.37% with a 3 dB bandwidth of 65 nm.