Dynamic bistability and spiral waves in a laser

We report on spiral wave patterns in a high-aspect-ratio two-level Lorenz-Haken laser. The pattern formation is investigated in a parameter region where the homogeneous steady state is linearly stable so that hard excitation is required to initiate inhomogeneous structures. In two-dimensional space, these phase waves rotate around their cores in domains separated by shocks while, in one-dimensional space, the system displays dynamic bistability and admits travelling solitary pulse solutions. © 1999 IOP Publishing Ltd.