The Effects of Ring Radius and Coupling Gap on the Transmission Spectrum of GaN-Based Ring Resonator

This paper proposes a design of an optical ring resonator based on GaN/sapphire waveguides for telecommunication links application using 1.55 μm wavelength. The ring resonator consists of a straight bus waveguide and ring waveguide separated by an air gap forming a directional coupler. The optimisation and analysis of the design were conducted using an FDTD method for TE mode with a centre wavelength of 1.55 μm. The numerical experiments were conducted for various ring radius and air gap. Results show the optimum ring radius for GaN ring resonator is 4 μm, and the optimum air gap is 40 nm.