Analysis of the Kerr Effect in a Resonator Fibre Optic Gyro (r-Fog) Under Accompanying Intensity Modulation with a Laser Diode
D. Ying, W. Wu, Q. Li, H. Ma and Z. Jin
We present an in-depth theoretical research on the Kerr effect in a resonator fibre optic gyro (R-FOG) under accompanying intensity modulation with a laser diode (LD). The expression for the Kerr effect induced drift under a laser diode’s accompanying intensity modulation caused by the resonance frequency drift of the fibre ring resonator (FRR) is provided. It is found that the resonance frequency fluctuation induced accompanying intensity modulation would cause a Kerr effect induced drift, which increases as the resonance frequency drift or the laser diode’s frequency-intensity conversion coefficient increases and could be as large as about 1.1 deg/h for an R-FOG with a 12.00 m fibre length fibre ring resonator. Numerical investigation shows that there exist the optimum modulation frequencies for suppressing this drift. But even if the modulation frequencies are optimized, this drift still could not be totally eliminated due to the fluctuations of the intensity coefficient and phase modulation index in the practical situation, and numerical simulation results show that the fluctuations for intensity coefficient and phase modulation index should be controlled to be less than about 0.5 and 0.7%, respectively for keeping the Kerr-induced drift to be less than 1.0 deg/h.
Keywords: Kerr effect, fibre optic gyro (FOG), resonator fibre optic gyro (R-FOG), laser diode, intensity modulation, fibre ring resonator (FRR), frequency-intensity conversion coefficient