A resonator fiber optic gyro was constructed using separate lasers for counter-rotating waves to overcome interference between optical backscatter and signal light that causes dead-zone behavior and scale factor nonlinearity. This approach enabled a 2 MHz frequency separation between waves in the resonator; eliminating the intended backscatter error. The two lasers were phase-locked to prevent increased gyro noise due to laser frequency noise. Dead-band-free operation near zero-rate, scale factor linearity of 25 ppm and stability of 11 ppm were demonstrated ─ the closest results to navigation-grade performance reported to date. The approach is also free of impractical frequency shifter technology.
A bench-top resonator fiber optic gyroscope (RFOG) was assembled and tested, showing encouraging progress toward
navigation grade performance. The gyro employed a fiber length of 19 meters of polarizing fiber for the sensing coil
which was wound on an 11.5 cm diameter PZT cylinder. A bias stability of approximately 0.1 deg/hr was observed over
a 2 hour timeframe, which is the best bias stability reported to date in an RFOG to our knowledge. Special care was
taken to minimize laser phase noise, including stabilization to an optical cavity which was also used for optical filtering,
giving angle random walk (ARW) values in the range of 0.008 deg/rt-hr. The ARW performance and bias stability are
within 2x and 10x, respectively, of many civil inertial navigation grade requirements.