Partition of the instantaneous and delayed nonlinear responses for the propagation of ultrashort solitons in optical fibers

Abstract

We address the long-standing issue of accurately partitioning the nonlinear response of silica glass into electronic (Kerr) and nuclear (Raman) contributions to correctly describe the propagation of ultrashort solitons in a unified way independently of their duration. This is done with a semianalytical approach leading to a modified nonlinear coefficient and thus to a modified condition for fundamental soliton propagation valid for durations much less, in the same order, or much greater than the characteristic time scale of the Raman response function. The results provided by this model are in good agreement with numerical integration of the nonlinear Schr\"odinger equation taking the Raman response into account.