Continuum-coupled solitary waves in a resonant amplifier with excited-state absorption

Abstract

Propagation of a short pulse in an amplifier with excited-state absorption (ESA) is considered. As is shown both analytically and numerically, if the stimulated emission cross section exceeds the ESA cross section, a steady-state pulse of a dissipative soliton type can exist. The parameters of the soliton, i.e., its width, amplitude, and velocity, are calculated. In the opposite case, amplification is inhibited unless ESA is suppressed using an additional control field applied to a transition adjacent to the ESA one [Phys. Rev. A 70, 043801 (2004)]. Propagation and amplification dynamics of a probe pulse in the presence of a strong control field is analyzed. In the limit of a continuous wave control field, a dissipative soliton solution forms, which is a pair of pulses similar to adiabatons. In the case of a pulsed control field, amplification of the probe pulse is transient. Conditions for optimal amplification are derived. Estimates of soliton parameters are made for rare-earth and transition-metal ion-activated laser crystals.