A slot microring sensor with feedback spiral waveguide for trace gas CH₄ sensing in mid-infrared region

Abstract

In this paper, a slot microring resonator with a piece of spiral feedback waveguide for CH₄ sensing application is proposed. This sensor is based on silicon-on-insulator (SOI) substrate and with the operation wavelength in mid-infrared region. To reach high sensitivity and good selectivity, slot cross section and spiral feedback waveguide are carefully tailored. The sensor shows ppb-scale trace gas sensing potential and is easy to be packaged in integrated photonics circuits. Calculation results show that the sensitivity reaches 1.4×10^-2 dB/ppm and the detection limit achieves 700 ppb in the case of L_spiral=100L_r.