Phase Modulation Approach to Closed-Loop, All-Fiber-Optic Gyroscope and Scale Factor Stabilization

Optical fiber gyroscopes showed high sensitivity and long term stability at zero rotation rate to make their practicability promising.1-3 It is also recognized that a closed-loop operation of fiber-optic gyroscope provides wide dynamic range of rotation sensing. Frequency shifters4 and magneto-optic effects5 have been utilized to generate a nonreciprocal phase shift that nulls out the rotation induced Sagnac phase shift for closed-loop gyroscopes. However, these types of closed-loop gyroscopes are not yet realized in an all-fiber configuration because suitable devices are not available at present in fiber form.