Hybrid linear and circular polarization Er-doped fiber ring laser gyroscopes

A bidirectional single-longitudinal-mode Er-doped fiber ring laser was proposed. Based on it, a fiber laser gyroscope was demonstrated. With circularly polarized lights in the Er-doped fiber, and linearly polarized lights in the rest part of the ring, a reciprocal structure was obtained, and the spatial hole burning effect was suppressed. In the experiments, the lock-in threshold rotation rate was 6 degrees/s. When the rotation rate was beyond 6 degrees/s, a beat RF signal of over 30-dB noise was observed and a good linear relation between the beat frequency shift and cavity rotation rate were obtained. Finally, the beat frequency stability was tested for 20 degrees/s clockwise cavity rotation.