Effect of a depolarizer in a fibre-optic gyroscope with a 3 × 3 coupler

Abstract

We present a simple digital processing method that provides a significant improvement for the performance of a phase-reading open-loop fibre-optic gyroscope. The phase-reading gyroscope measures the angular speed in terms of a phase difference between the two counter-propagating beams in the Sagnac interferometer. Instead of electronic phase meters we use a very simple PC-based digital process which computes the Sagnac phase. With this method we measure rotation rates down to 100°h−1. The errors of this scheme are studied for different signal-to-noise ratios and the number of bits of the analog-to-digital converter.