Integrated optical interferometer as relative humidity sensor and differential refractometer

Abstract

We demonstrate a novel integrated optical interferometer which responds to changes in the relative humidity of gaseous samples and to changes in the refractive index of liquid samples. This common-path interferometer, which can be fabricated without any microstructuring process, consists of a planarmonomode (SiO2-TiO2) waveguide in which the TE0 and TM0 modes are coherently excited; their time-dependent phase difference caused by the interaction with the sample is measured. © 1991.