Design of SiN_x Optical Sensor Using Polygonal Resonator Structure

摘要

In this paper, SiN_x polygonal resonator is carefully simulated for an optical sensor. The polygonal resonator has recently attracted much attention for application in bio and chemical sensors because it does not have a bending loss, which can be fabricated with high integration rate, and it has an advantage of using Multi Mode Interference (MMI) coupler. In polygonal resonator sensor design, high Q-factor and low loss Total Internal Reflection (TIR) mirror are important factors. Therefore, a 125 degrees TIR mirror that has a 97% reflectance considering the Goos-Hanchen shift and critical angle is designed. For rib type waveguide, we designed it to have 3 μm width, 0.5 μm height, and 0.25 μm etching depth. Regarding the simulation results of Finite Domain Time difference (FDTD) method, the Q-factor of SiN_x polygonal resonator was 5736 and Free Spectral Range (FSR) was 16.3 nm. When we changed the refractive index, the shift of the peak was 26.5 nm/Refractive Index Unit (RIU).