Silicon photonics efficient fiber coupler based on a metastructure with minimum feature size of 150 nm

We propose a silicon photonics fiber coupler consisting of a metastructure containing a through-hole array and a partially etched grating to obtain high efficiency. Using an evolution optimization algorithm, we optimized 121 structural parameters and achieved a minimum feature size of 150 nm, which greatly simplifies the fabrication using wafer-scale foundry services. We designed two structures, one achieving an 86% coupling efficiency into a single 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.