Pulse Evolution in Birefringent Fibers under the Influence of Four-Wave Mixing and Stimulated Raman Scattering

Abstract

The propagation of high power laser pulses through glass fibers is affected by nonlinear optical effects which can be described by the third order nonlinear susceptibility χ(3) = χ′(3)+ iχ″(3). The real part contains self- and cross-phase-modulation (SPM and XPM) causing spectral broadening, and it is responsible for the parametric four wave-mixing process (FWM) which leads to the generation of a Stokes/anti-Stokes wave pair and requires phase matching. The imaginary part describes Stokes frequency conversion due to stimulated Raman Scattering (SRS). This process is always self phase matched. Most of the research work published has treated the effects of SRS and FWM independently [1] even though they may act simultaneously [2]. A simultaneous treatment becomes necessary when the frequency shift at which phase matching occurs falls within the Raman amplification profile. In this paper we present experimental and theoretical results of the combined action of FWM and SRS in a birefringent fiber under the influence of SPM, XPM and group velocity dispersion.