Two major architectures of fiber optic gyroscopes have been under development at Honeywell in recent years. The interferometric fiber optic gyro (IFOG) has been in production and deployment for various high performance space and marine applications. Different designs, offering very low noise, ranging from better than navigation grade to ultra-precise performance have been tested and produced. The resonator fiber optic gyro (RFOG) is also under development, primarily for its attractive potential for civil navigation usage, but also because of its scalability to other performance. New techniques to address optical backscatter and laser frequency noise have been developed and demonstrated. Development of novel, enhanced RFOG architectures using hollow core fiber, silicon optical bench technology, and highly stable multifrequency laser sources are discussed.
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.
A benchtop experimental resonator fiber optic gyro (RFOG) was assembled and tested. The gyro employed a fiber length of
19 meters of polarizing fiber for the sensing coil which was wound on a 4.5 inch diameter piezoelectric cylinder. Angle
random walk (ARW) values in the range of 0.0075 to 0.0085 deg/rt-hr were observed against a calculated shot noise limit
of 0.0053 deg/rt.-hr for this experimental arrangement. To our knowledge, this is the first ARW result reported for an
RFOG that is consistent with commercial navigation-grade performance.