Femtosecond nature of stimulated Raman scattering in optical fibres: the possibility of `dark´ soliton generation

Nonlinear pulse propagation in an optical fibre is described by the nonlinear Schrodinger equation which predicts the existence of bright solitons (envelope solitons) in the region of negative chromatic dispersion of an optical fibre and dark solitons (a dip in the constant radiation level) in a region of positive dispersion. Since SRS starts from spontaneous emission then it seems quite reasonable to investigate the temporal nature of the radiation in order to establish a symmetry between the positive and negative regions of the group velocity dispersion of an optical fibre. The author studies the temporal characteristics of SRS in a single mode optical fibre