Design of a hydrogen sulfide gas sensor based on a photonic crystal cavity using graphene

We report the design and simulation of a high sensitivity H2S gas sensor using a combination of graphene properties as a hydrogen sulfide-sensitive nanomaterial and features of photonic crystal cavity. The shoulder-coupled resonant cavity is introduced in the photonic crystal that consists of a triangular array of air holes on the silicon-on-insulator substrate. To adsorb H2S gas, a graphene layer is deposited on the inner wall of the two cavity air holes. Changes in the concentration of hydrogen sulfide gas alter the refractive index of graphene, thereby resulting in wavelength shift in the sensor transmittance spectrum. We achieved a sensitivity of 1.2 × 104 nm/RIU and a detection limit of 1.87 × 10−6 RIU. To the best of our knowledge, the sensitivity of our sensor is much higher than other sensors previously reported in the literature.