Fiber optic gyroscope noise reduction with fiber ring resonator

A method of improving the angular random walk (ARW) of a fiber optic gyroscope (FOG) using a fiber ring resonator (FRR) to reduce the relative intensity noise (RIN) is demonstrated. An FRR reduces the RIN near the proper frequency and improves the ARW. The analytical forms for the RIN transfer function and the power transmission of the FRR are derived when the free spectral range of the FRR is much narrower than the source bandwidth. Building the FRR using couplers and fiber with low excess loss enhances the RIN reduction. For the coupling ratios, there is a trade-off between the RIN reduction and the power transmission. The coupling ratios are 90%-10% tap in the experiment. When the FRR resonator length is shorter than the FOG coil length, the ARW improvement is further enhanced by adjusting the average window length in the signal processing. An experiment demonstrated a 7 dB decrease in the RIN at the loop proper frequency, which reduces the standard deviation by 3.5 dB. The ARW was reduced from 970 to 570  μdeg/h^1/2, which amounts to a 2.3 dB reduction.