Research on application of laser in interferometric fiber optic gyroscope for excellent scale factor stability

In order to improve the scale factor stability of interferometric fiber optic gyroscope (IFOG), laser is considered to be an alternative to traditional broadband light source because of its excellent frequency stability. Although the performance of IFOG driven directly by laser is inspiring, it is still necessary for further improvement. The main limiting factor is its narrow linewidth and errors of coherent backscattering, polarization coupling and Kerr effect will be reintroduced in laser-driven IFOG. At present, one of the best methods is using Gaussian white noise (GWN) to drive an external electro -optic phase modulator (EOM) and broaden the optical spectrum of laser which will not cause additional frequency drift to the laser. This review studies the mechanism of phase modulation comprehensively based on theory and simulation. The process of broadening is described by numerical calculation and OptiSystem platform. The spectrum is also broadened as expected in the experiment observed by optical spectrum analyzer (OSA). Furthermore, by broadening the linewidth before laser enters the IFOG system, its angular random walk noise and drift are improved by more than 60% compared with no modulation. The test results also show that the drift has reached the level of broadband light source. Related work enriches the application of laser as light source in IFOG and the research about external phase modulation.