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

Abstract We propose and characterized a silicon microring resonator (Si MRR) optical hydrogen sensor that employs a Pt/WO₃–SiO₂ thin film as a hydrogen-sensitive layer to achieve highly sensitive hydrogen detection. Pt/WO₃–SiO₂ exhibits higher heat-generation performance than conventional Pt/WO₃. The Pt/WO₃–SiO₂ thin film was formed by a spin-coating method. The sensor detects hydrogen by monitoring the resonance-wavelength shift caused when the reaction heat generated by the interaction with hydrogen is transferred to the waveguide. In hydrogen exposure measurements, resonance-wavelength shifts of approximately 5.0 nm and 2.4 nm were observed for 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/WO₃–SiO₂ film.