Oscillating Directional Domains in a Ring Semiconductor Laser

We analyze transverse effects in a macroscopic class-A ring semiconductor laser based on a broad stripe gain medium. While the simplest modeling of such a device suggests the existence of stable domains emitting in opposite directions, the presence of alternate oscillations in the device prevents the stability of these domains. We describe the experimental observation of alternate oscillations and the associated transverse dynamics. A numerical analysis which drops many common assumptions shows that the presence of traveling domain walls is a sufficient driving force for the alternate oscillations.