Integrated Optical Interferometers for Low Coherence Sensing Applications

Abstract

Fibre optic low-coherence interferometry is of great interest for industrial sensing applications In general, systems use a low-coherence source to illuminate two interferometers with matched optical path differences (OPD), greater than the source coherence length. Typically, the first interferometer is used as a sensor, for example micro-machined silicon resonant sensors [1], where a reference and modulated sensing signal are derived from the sensor head. Due to the large OPD the two signals can propagate together without interference. The second interferometer acts as a detector, where due to its matched OPD, the signals from the sensor head are brought back into coherence and interfere.