Design of low loss bend waveguides with uniform width and a high-Q micro-ring resonator structure

This article proposes an equivalent curvature theory and a bending waveguide design method that maintains a uniform width during the bending process, which takes into account the effect of the waveguide width on the loss. A micro-ring resonator (MRR) in a silicon-on-insulator (SOI) platform was designed through this method. From the ring resonator with R_eff of 5 µm, the Q has been raised to 31314 (versus 22313 for Euler ring and 10418 for circular ring), the Finesse has been raised to 460 (versus 314 for Euler ring and 166 for circular ring). Reducing waveguide loss at small radii provides more pathways for enhancing the compactness and efficiency of silicon photonic devices.