Abstract

We describe and demonstrate a new type of phase-conjugate fiber-optic gyro¹ (PCFOG). PCFOGs use phase conjugation to compensate for reciprocal phase changes due to thermal and mechanical effects on the fiber, while at the same time allowing for the measurement of the nonreciprocal phase shift produced by rotation. Where the best standard fiber-optic gyros require polarization-preserving fibers and couplers to avoid polarization scrambling that is a source of noise and signal fading, PCFOGs can avoid this problem by using polarization-preserving phase conjugation.² This has the advantage of allowing for the use of inexpensive nonpolarization preserving and even multimode fibers and components. The double PCFOG is simply an interferometer, in which both arms contain fiber-optic coils terminated by the same self-pumped phase-conjugate mirror. We have recently demonstrated rotation sensing using such an interferometer with a self-pumped crystal of barium titanate as the phase-conjugate mirror. For this demonstration, the entire interferometer was mounted on a rotary table and light was piped to the table using a fiber optic. In addition to the simplicity of the new self-pumped version of the PCFOG, it has the advantage of allowing for the use of fiber-optic coils that are longer than the coherence length of the laser to increase the sensitivity of the gyro.

© 1986 Optical Society of America