In Brillouin fiber lasers, the phase fluctuations of the pump laser are transferred to the emitted Stokes field after being strongly reduced. The result is a linewidth narrowing that we study both experimentally and theoretically. We derive simple expressions to connect the linewidths of the waves interacting in the fiber, and we show that the magnitude of the narrowing effect depends only on the acoustic damping rate and the cavity loss rate. We successfully compare these theoretical predictions with experimental results obtained by recording the response of a Brillouin fiber ring laser to frequency modulation of the pump field.
© 2001 Optical Society of America
(030.1640) Coherence and statistical optics : Coherence
(140.3560) Lasers and laser optics : Lasers, ring
(190.4370) Nonlinear optics : Nonlinear optics, fibers
(290.5900) Scattering : Scattering, stimulated Brillouin
Alexis Debut, Stéphane Randoux, and Jaouad Zemmouri, "Experimental and theoretical study of linewidth narrowing in Brillouin fiber ring lasers," J. Opt. Soc. Am. B 18, 556-567 (2001)