The resonant fiber optic gyro (RFOG) is a high accuracy inertial rotation sensor based on the Sagnac effect. The existence of various noises, including the nonreciprocal noises such as the polarization noise and the Kerr noise as well as the reciprocal circuit noise, limits the performance improvement of the RFOG. An improved scheme by inserting two in-line polarizers in the polarization maintaining fiber transmission-type resonator has been proposed to suppress the polarization-fluctuation induced drift. Furthermore, the adoption of the air-core photonic bandgap fibers (PBFs) offers a novel solution to reduce the optical Kerr effect. In addition, A digital signal processor is designed to reduce the reciprocal noises and detect the rotation information. A minimum actual rotation of 0.001°/s is achieved. The dynamic range is improved by a factor of 7 and the scale factor nonlinearity is decreased by a factor of 60.
A double closed-loop resonant micro optic gyro (RMOG) employing a hybrid digital phase modulation technique is demonstrated, showing encouraging progress. In this hybrid modulation scheme, the width of one stair of the stair-like digital serrodyne wave is optimized according to the rise time of the digital-to-analogue converter to obtain the maximum sideband suppression. Based on the optimum parameters of the hybrid modulation scheme, a typical bias stability of 0.05/s in 1 hr is demonstrated in an RMOG with a silica waveguide ring resonator having a ring length of 7.9 cm. This is the best long-term performance which has ever been reported in an RMOG to our knowledge.
A novel hybrid polarization-maintaining (PM) air-core photonic bandgap fiber (PBF) ring resonator is demonstrated by using a conventional PM fiber coupler formed by splicing a section of air-core PBF into the resonator. The coupling loss between the PM air-core PBF and the conventional solid-core PM fiber is reduced down to ∼1.8 dB per junction. With the countermeasures proposed to reduce the backscattering induced noise, a bias stability of approximately 0.007 °/s was observed over a 1 hour timeframe, which is the best result reported to date, to the best of our knowledge, for RFOGs equipped with a hybrid air-core PBF ring resonator.
A resonant micro optic gyro (RMOG) is a promising candidate for applications requiring small, light and robust gyros. A high-performance RMOG requires a low-loss micro-ring resonator, and thus a resonator having a high finesse. We experimentally create a new record for high-finesse micro-ring resonators by using 30-cm long low-loss fiber coils laid into the V-groove on a silicon substrate. Both the simulation and experimental results indicate that the 30-cm long micro-ring resonator is sufficient to build a tactical-grade RMOG. Experimentally, a bias stability of 0.046/s in 1800 s with an integration time of 1 s is successfully demonstrated.