title: Noise induced in optical fibers by double Rayleigh scattering of a laser with a 1/fν frequency noise.
abstract: We study, theoretically and experimentally, intensity noise induced by double Rayleigh scattering in long optical fibers. The results of the theoretical model are compared to experimental results performed with a high-coherence-length laser with a frequency noise spectrum that is dominated by 1/fν noise. Excellent quantitative agreement between theoretical and experimental RF spectra were obtained for frequencies as low as 10 Hz and for fiber lengths between 4 and 45 km. Strong low-frequency intensity noise that is induced by 1/fν frequency noise of the laser may limit the performance of interferometric fiber optic sensors that require high-coherence-length lasers. The intensity noise due to double Rayleigh backscattering can be suppressed by reducing the coherence length of the laser. Therefore, the intensity noise has a complex and non-monotonic dependence on the 1/fν frequency noise amplitude of the laser. Stimulated Brillouin scattering will add a significant noise for input powers greater than about 7 mW for a 30 km length fiber.
authors.forename: Michael
authors.initials: M
authors.lastname: Fleyer
authors.forename: Seth
authors.initials: S
authors.lastname: Heerschap
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Cranch
authors.forename: Moshe
authors.initials: M
authors.lastname: Horowitz