Fiber gyroscope with nonreciprocally operated, fiber-coupled LiNbO(3) phase shifter

We describe a fiber gyroscope operating at maximum sensitivity that is due to a nonreciprocal pi/2 phase bias effected with a pulsed voltage applied to an electro-optic LiNbO(3) channel waveguide phase shifter. With a He-Ne laser source, the noise was equivalent to a 0.1 degrees /sec rotation, for a 10-Hz bandwidth and 2% reflectivity at each fiber-LiNbO(3) interface. The phase shifters showed polarization-independent behavior that was characterized by measurements in a fiber interferometer. They were flip-chip coupled with single-mode fiber that were cemented to the channel ends to give a stable module.