Modeling of coupling loss in ultra-compact SOI microring resonators

Ultra-compact microring resonators, made of high index contrast (HIC)-silicon on insulator (SOI) mate-rials, have become key optical devices in integrated photonics systems. Both computer simulations andactual experiments have showed that coupling loss was a significant contributor to the total losses inultra-compact microring resonators. In this paper, a computable model derived from step approximationmethod was present to theoretically determine the coupling loss. Excellent matching results betweenthe model and literatures were achieved. The proposed model can be applied to evaluate the couplingloss for microring resonators with various geometries and guide the design of low loss optical devicesbased on ultra-compact microring resonators.