Soliton Structures in the Excitation due to Induced Absorption

Abstract

It will be shown that in a nonlinear optical medium whoes absorption coefficient increases with the excitation density (e.g., free-carrier concentration in a semiconductor or temperature) , a soliton structure in the excitation density can occur, which in the stationary case is approximately the solution of a Sine-Gordon equation. For changing light intensity the soliton wall between the highly excited front part of the crystal and the weakly excited end part can move only in discrete jumps due to the intrinsic bistability. Experimental observations of these predictions have been obtained recently by Gibbs et al..