Abstract

An integrated-optic displacement sensor is described. A double Michelson interferometer,¹ built up by ion-exchanged, monomode (633-nm) waveguides in glass, combines a fast forward/backward movement detection by orthogonal signals with a high-resolution (1-nm) displacement sensing by optical heterodyning. The complex optical structure in combination with a collimating gradient-index lens provides two reference arms, offering a fast displacement detection over a wide measuring range (10 cm) with a limited resolution of 1/8 wavelength (79 nm). An integrated thermo-optical modulator increases the resolution of the sensor up to 1 nm by an optical phase modulation single sideband detection² technique with 1-kHz frequency offset.

© 1991 Optical Society of America