Optical hydrogen gas sensor based on silicon microring resonator with Pt/WO 3 –SiO 2 film

Abstract We propose and characterize a silicon microring resonator (Si MRR)-based optical hydrogen sensor that employs a Pt/WO 3 –SiO 2 thin film as a hydrogen-sensitive layer for highly sensitive hydrogen detection. Pt/WO 3 –SiO 2 exhibits higher heat-generation performance than conventional Pt/WO 3 . The Pt/WO 3 –SiO 2 thin film was formed by spin coating. The sensor detects hydrogen by monitoring the resonance wavelength shift induced by the transfer of reaction heat, generated through interaction with hydrogen, to the waveguide. In hydrogen exposure measurements, resonance wavelength shifts of approximately 5.0 nm and 2.4 nm were observed at hydrogen concentrations of 4.0 vol% and 0.4 vol%, respectively, demonstrating the high sensitivity of the proposed sensor. These results confirm the effectiveness of the Si MRR hydrogen gas sensor employing a Pt/WO 3 –SiO 2 film.