Design of On‐Chip Multi‐Slot Chalcogenide Waveguide for Mid‐Infrared Methane Sensing

Abstract

A chalcogenide (ChG) multi‐slot waveguide gas sensor with ChG as the core layer and silicon dioxide (SiO2) as the under‐cladding layer is proposed. Multi‐slot waveguide can be used in the mid‐infrared gas measurement. The optimized power confinement factor (PCF) of the ChG multi‐slot waveguide can be up to 41.3%, which is ∼20% higher than that of the optimized single‐slot waveguide. At the absorption line located at 3.291 μm for methane (CH4) measurement, the limits of detection (LoD) of single‐slot, double‐slot, triple‐slot, quadruple‐slot waveguide sensors are determined to be 68.9, 57.4, 52, 48.6 parts per million (ppm), respectively. Compared with other waveguide sensors in the mid‐infrared, the PCF of the proposed multi‐slot ChG/SiO2 waveguide sensor is enhanced by five times, which has the potential for highly sensitive gas sensing.