Sensitivity analysis of the Sagnac-effect optical-fiber ring interferometer

The sensitivity of a recently reported optical-fiber ring interferometer as a gyroscope has been analyzed. Photomixing SNRs were derived for the detection schemes. Noise sources due to the Rayleigh, Brillouin, Mie, and core-cladding interface light scattering processes are assessed quantitatively. Optimum gyroscope sensitivities are discussed via numerical examples for optical wavelengths lambda = 0.633 microm and lambda = 1.1 micro and both spontaneous and stimulated noises. Results show that (a) to reduce trapped scattered light by a factor of 100, mode stripping is essential, (b) lambda = 1.1 microm is a more promising wavelength to use, and (c) high optical power operation, where the only noise is due to stimulated Brillouin scattering, gives better sensitivity than the low-power case. Examples show that at lambda = 0.633 microm, the achievable sensitivities are 0.0078 deg/h at 2 mW and 0.0009 deg/h at 81 mW; and at lambda = 1.1 microm, they are 0.0025 deg/h at 2 mW and 0.0007 deg/h at 14.4 mW. These calculated sensitivities are better than those of current laser ring gyroscopes.