M N VINOJ and V C KURIAKOSE

Department of Physics, Cochin University of Science and Technology, Kochi 682 022, India

Email: vinojmn@cusat.ac.in; vck@cusat.ac.in

Abstract.

In this paper, we consider nonlinear Schrödinger (NLS) equations, both in the anomalous and normal dispersive regimes, which govern the propagation of a single field in a fiber medium with phase modulation and fibre gain (or loss). The integrability conditions are arrived from linear eigen value problem. The variable transformations which connect the integrable form of modified NLS equations are presented. We succeed in Hirota bilinearzing the equations and on solving, exact bright and dark soliton solutions are obtained. From the results, we show that the soliton is alive, i.e. pulse area can be conserved by the inclusion of gain (or loss) and phase modulation effects.. 

Keywords:  Optical solitons; bright and dark solitons; nonlinear compression; phase modulation; fibre amplification; loss.

Pacs Nos.  42.81. Dp; 02.30 Jr; 04.30 Nk