High efficiency silicon photonics grating coupler compatible to standard foundry service

We propose a silicon photonics fiber coupler consisting of a metastructure containing a through-hole array and a partially etched grating to obtain a high efficiency. Using an evolution optimization algorithm, we optimized 121 structural parameters and achieved a minimum feature size of 150nm, which greatly simplifies the fabrication using wafer-scale foundry services. We designed two structures, one achieving a 86% coupling efficiency into a singlemode fiber, and the other exhibiting a full flat spectrum in the C band. The high-efficiency structure was fabricated using a 300-mm wafer process, and an efficiency of 78% was experimentally evaluated.