Deformation of modulated wave groups in third-order nonlinear media

We present a numerical and analytical investigation of the deformation of a modulated wave group in third-order nonlinear media. Numerical results show that an optical pulse that is initially bichromatic can deform substantially with large variations in amplitude and phase. For specific cases, the bi-chromatic pulse deforms into a train of temporal solitons. Based on the coupled phase-amplitude equation of Nonlinear Schrödinger (NLS), the initial deformation of the modulated wave-packet will be explained and an instability condition can be derived. Energy arguments are given that provide an alternative derivation of the instability condition.