We examine the effect of damping on the nonlinear modulation of an electromagnetic plane wave in a ferrite. Depending on the value of the damping constant, the time evolution of the amplitude of the wave is either a simple exponential decay, or is described either by a nonlinear Schrödinger (NLS) equation, or by a perturbed NLS equation. We give a new exact solution to this latter equation, and a way to compute approximate solutions
