Four-wave-mixing-induced turbulent spectral broadening in a long Raman fiber laser

We present a detailed analytical self-consistent theory based on wave kinetic equations that describes generation spectrum and output power of a Raman fiber laser (RFL). It is shown both theoretically and experimentally that the quasi-degenerate four-wave mixing (FWM) between different longitudinal modes is the main broadening mechanism in the one-stage RFL at high powers. The shape and power dependence of the intracavity Stokes wave spectrum are in excellent quantitative agreement with predictions of the theory. FWM-induced stochasticity of the amplitude and the phase of each of the similar to 10(6) longitudinal modes generated in the RFL cavity is an example of a light-wave turbulence in a fiber. (c) 2007 Optical Society of America.