Integrated micro-ring resonator-based Bragg grating for gas sensing applications

This paper proposes an optical gas sensor design using the Silicon on Insulator (SOI) platform. The design aims to achieve a resonance peak centered at a specific wavelength in the near-infrared region. The device consists of two concentric silicon rings, each with Bragg gratings superimposed externally and internally, respectively, creating a Grating Slot Micro-Ring Resonator (GSMRR). The device filters the optical transmission through two-step processing. First, the light traveling through the bus waveguide is filtered by the SMRR, and then the resonant light is filtered by the Bragg grating. Both the SMRR and Bragg grating are designed to operate at the same wavelength, near 1550 nm, which corresponds to the main resonance peak of the structure. The Finite Difference Time Domain (FDTD) analysis is employed using the Lumerical commercial tool to simulate the behavior of the electromagnetic fields. The device is able to detect the shifts in the main resonance due to changes in refractive index with high efficiency, which is an important feature for sensing applications. We demonstrate that our sensor achieves a small footprint, high sensitivity, and high Figure of Merit, which make it ideal for accurate and reliable gas sensing applications.