Loop-terminated Mach-Zehnder interferometer for gas sensing on silicon-on-insulator platform

We demonstrate the use of a loop terminated Mach Zehnder interferometer implemented on a functionalized silicon on insulator photonic integrated platform for low concentration gas detection with a limit of detection of 50ppb. The sensing arm is coated with a functionalized SU-8 layer that adsorbs the analyte. The method is demonstrated experimentally for acetone at telecom wavelengths. As such we achieve the implementation of highly sensitive and inexpensive devices for onsite and real-time environmental monitoring and medical diagnostics.