Abstract

In some recent experiments¹ new kinds of instability have been observed that are possibly related to the competition between two transversal modes. The theoretical study of spatial and temporal dynamics is a numerical problem of tremendous complexity that usually implies a delay between experiments and theory. We present here a model that allows us to describe the dynamics of a laser emitting in two different transversal modes without excessive complexity. The model is based on the assumption that both modes have a fixed spatial profile and the temporal dynamics is driven by the averaged coupling of both fields at each point of the amplifier. We also present results obtained with an oversimplified model that divides the molecules of the active material into three different categories. One is the group of molecules placed in the regions of space where only one mode is present, the other is the group of molecules placed where only the other mode is present, and the third group is the molecules placed in points where both modes are present.

© 1989 Optical Society of America