Technology and performances of silicon oxynitride waveguides for optomechanical sensors fabricated by plasma-enhanced chemical vapour deposition

The technology and performance of micromachined channel waveguides, based on plasma-enhanced chemical vapour deposition (PECVD) of silicon oxynitride thin films, are presented. The deposition parameters of PECVD are studied in connection with their optical, mechanical and chemical properties. The design of the waveguide is optimised for single mode operation, low loss propagation and high efficiency of coupling to single mode optical fibers. This technology is applied to fabricate the pigtailed Mach-Zehnder interferometers, where the coupling from the optical fiber to the waveguide is based on U-groove etch, supporting fibers in the same substrate as the waveguide substrate.