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Femtosecond optical pulses; nonlinear media; third-order dispersion; self-steepening; stimulated Raman scattering.

We model the propagation of femtosecond pulses through optical fibres by a nonlinear Schrödinger (NLS) equation involving a perturbing term arising due to third-order dispersion in the medium. The perturbative effect of this higher-order dispersion causes the usual NLS soliton to emit a radiation field. As a result, the given initial pulse propagating through the fibre exhibits nonsolitonic behaviour. We make use of a variational method to demonstrate how an initial pulse by the interaction with the emitted radiation can evolve into a soliton. We also demonstrate that the effect of interaction between the initial pulse and radiation field can be accounted for by including, in the evolution equation, terms associated with self-steepening and stimulated Raman scattering that characterize the optical medium.

Debabrata Pal¹ S K Golam Ali¹ B Talukdar¹

1. Department of Physics, Visva-Bharati University, Santiniketan 731 235, India

Published

June 2009

Manuscript received

26 September 2008

Manuscript revised

19 March 2009

Accepted

1 May 2009