Abstract

We showed recently¹ that the coupling between different transverse cavity modes yields spatiotemporal instabilities in a CO₂ laser system using the radius of curvature of the mirrors as the control parameter to change the strength of such a coupling. Our results were in good agreement with theoretical calculations based on a modal expansion of the Maxwell-Bloch equations. However, the model was based on an intrinsic radial symmetry of the transverse configuration of the field, while in the experiment that assumption was shown to fail when the separation in frequency of the empty cavity modes was reduced below a certain critical value.¹

© 1989 Optical Society of America