Integration of a Laser into an Interferometric Fibre Optic Gyroscope (IFOG) for Excellent Scale Factor Stability
J-T. Yan, Y-S. Liu, L-J. Miao, K. Liu, T-C. Huang and S-L. Che
Scale factor stability of an interferometric fibre optic gyroscope (IFOG) has been challenging due to the use of broadband light source. In this paper, laser with excellent frequency stability is proven to be able to drive an IFOG. As a result of its narrow linewidth, errors namely coherent backscattering, polarization coupling and Kerr effect are reintroduced. Based on the most advanced models, we analyse and calculate these terms approximately to demonstrate the feasibility of using laser as light source in an IFOG system theoretically. Its 3 dB linewidth is measured by delayed self-heterodyne interferometer and the high precision alignment method of fibre fusion is restated to reduce polarization error. By choosing the appropriate laser with a suitable driving current the noise of 0.010°∕√h, drift of 0.050 °∕h and scale factor stability of 1.88 ppm are achieved simultaneously. As the wavelength stability of broadband light source is becoming more and more difficult to improve, laser-driven IFOG will be a potential research direction in the future.
Keywords: Semiconductor laser, interferometric fibre optic gyroscope (IFOG), laser-driven, scale factor, full width at half maximum (FWHM), frequency stability, random walk noise, drift