Ultra-sensitive and compact on-chip gas sensor on a silicon nitride photonic integrated circuit (Conference Presentation)

We demonstrate a compact on-chip gas sensor based on a SiN photonic integrated circuit providing an estimated detection limit of 0.1ppm for a variety of gas vapors, including IPA, ethanol and acetone. The sensor consists of an integrated Mach-Zehnder interferometer having one arm coated with an absorptive mesoporous layer to enhance the interaction of the gas vapors with the waveguide evanescent field. Gas detection is accomplished by monitoring the spectral shift of the output signal induced by a change in the effective refractive index of the coated waveguide. Results pave the way to novel integrated solutions for environmental safety monitoring.