Imbalanced Mach-Zehnder interferometer integrated in micromachined siliconsubstrate for pressure sensor

This paper describes an interferometric pressure sensor designed to work as a remote sensor in a coherence modulation scheme, allowing a linear phase read-out of the signal. The sensor is realized from a silicon nitride waveg uide Mach-Zehnder integrated on a (100) silicon substrate, and includes a m icromachined membrane below a branch of the Mach-Zehnder. The characterizat ion is achieved by a spectral analysis and shows a nonlinear relationship b etween the static pressure applied to the membrane and the phase variation thus obtained, The analytical description takes into account the induced de flection of the membrane and the resulting mechanical elongation of the wav eguide.