Temporal effects in long-pulse multi-order stimulated Raman scattering in optical fiber

Summary form only given. When sufficiently long optical pulses propagate through low loss optical fiber the temporal effects of linear dispersion can be neglected in modeling the propagation, and the dominant effects are nonlinear processes. This widely used approximation is called the quasi-continuous wave approximation since it eliminates any explicit reference to time in the propagation equations; this model is common in the study of stimulated Raman scattering (SRS) of long pulses in optical fiber. However, because SRS is intensity dependent, one expects the temporal shape of the pulses to influence the transfer of energy from the pump to the Stokes orders. We show here that the detailed temporal shape of the pulse is especially important at high pump powers where several Stokes orders are generated in the fiber. In particular, to achieve agreement between experiment and theory requires the inclusion of both the overall temporal shape of the pulse pulse envelope and the detailed structure for multi-mode pump pulses. We believe that this is the first detailed comparison of theory and experiment for strongly saturated SRS in optical fibers.