Thresholds of envelope soliton formation in a weakly dissipative medium

Thresholds of envelope soliton formation from input rectangular pulses of amplitude b and duration T in a nonlinear dispersive medium with weak dissipation are calculated. The calculated threshold curve b(th)(2) = f(1/T-2) has n minima corresponding to the formation of 1,2,..., n envelope solitons. The positions and magnitudes of these minima an determined by the dissipation parameter in the medium. The derived threshold formula provides a quantitative description of the threshold curve measured recently for spin wave envelope solitons in yttrium-iron-garnet films.