Simulation of ZnO-coated SOI microring resonant shift response to ethanol and ammonia

A compact silicon-on-insulator microring resonator coated with porous ZnO layer for gas sensing is proposed in this paper. Based on the sensing system designed, we simulated the output spectra of two different sample gases, ethanol vapor and ammonia gas. The variable gas concentration we choose in this work range from 0 to 3‰. The molecule sizes of them are in different orders of magnitude, leading the sensitivity curves to show thoroughly different trends. The significant difference of two curves suggests that these two types of reducing gas obey different absorption principles depending on the size disparity between gas molecules and ZnO nanocrystals coated on ridge waveguide.