Optimizing photonic crystal micro ring resonators (PhC-MRRs) via bending supercell simulations

Photonic crystal micro-ring resonators (PhC-MRRs) hold promise as compact, high-Q cavities, for a plethora of on-chip applications. However, the challenges of mode matching and resonance analysis in these devices pose significant design hurdles, compared with straightforward waveguide based MRRs. In this study, we propose an extended supercell containing both straight and bending structures that satisfy the periodicity requirements. This supercell structure, which is optimized to reduce corner reflections, features a lattice constant, a = 364 nm and filling factor, f₀ = 0.33. We extend the supercell to construct a hexagonal PhC-MRR with radius of 13a and 'bus-to-ring' coupling gap, g = 3a. The PhC-MRR structure with what we refer to as 'mirror optimized' corners exhibits a transmission spectrum with six, equally spaced, high-Q pure guided cavity resonances with a free spectral range (FSR) of 18 nm, across a broad bandwidth from 1500 nm to 1600 nm.