Beam self-focusing in the presence of a small normal time dispersion

Abstract
We present a system of modulation equations that approximate the focusing of the nonlinear Schrödinger equation in the presence of a small normal time dispersion (TDNLS). Since the modulation equations are much easier for analysis and for numerical simulations, they can be used to get a general picture of the TDNLS focusing. Analytical and numerical agreement between the modulation equations and the TDNLS is established.