聚合物波导光栅耦合器的衍射场仿真

为了实现横截面尺寸为50 m50 m的聚硅氧烷聚合物光波导的耦合转向问题，设计了一种表面覆盖高折射率包层的多层蚀刻光栅耦合器。首先，分析了影响聚合物波导光栅耦合器耦合效率的结构因素；然后，采用在光栅表面蚀刻高折射率层的方法，提高了聚合物波导光栅耦合器的耦合效率；接着，对不同的周期（范围:100~4 000 nm）和不同的蚀刻深度（范围:0~50 000 nm）进行排列组合，形成不同的光栅结构，基于时域有限差分法编写程序，遍历所有情况，得到不同光栅结构下的光场情况以及其耦合效率，找到使耦合效率最大的周期以及蚀刻深度。最后，设计了多层蚀刻的光栅耦合器，进一步提高耦合效率。当蚀刻深度为5 000 nm，光栅周期为2 600 nm时，带高折射率层的聚硅氧烷聚合物光波导均匀光栅耦合器的耦合效率达到最大，为17.2%。采用多层蚀刻的方式，对结构进行优化，其耦合效率能达到37.4%。为聚硅氧烷聚合物光波导在光互连中的实际应用提供了理论依据。

Diffraction field simulation of polymer waveguide grating coupler

In order to realize the coupling and steering of polysiloxane polymer optical waveguides with a cross-sectional dimension of 50 m50 m, a multilayer etched grating coupler with high refractive index cladding was designed. Firstly, the structural factors affecting coupling efficiency of polymer waveguide grating couplers were analyzed. Then, the coupling efficiency of polymer waveguide grating coupler was improved by etching the high refractive index layer on the grating surface. Next, different grating structures were formed by arranging and combining different periods (range:100-4 000 nm) and different etching depths (range:0-50 000 nm), where all cases were traversed to obtain the diffraction field distribution and its coupling efficiency of different grating structure based on finite-difference time-domain (FDTD) method. Beyond that, the optimization of period and etch depth were found to maximize coupling efficiency. Finally, a multilayer etched grating coupler was designed to further improve the coupling efficiency. The coupling efficiency of the uniform grating coupler with high refractive index layer was approximately 17.2% with 5 000 nm etching depth and the 2 600 nm grating period. The coupling efficiency is approximately 37.4% with multilayer etching and optimized structure. It provides a theoretical reference for the practical application of polysiloxane polymer optical waveguide in optical interconnection.