We present theoretical and experimental evidence for a new type of multimode instability in a homogeneously broadened ring-laser system. The unstable behavior discussed in this paper is the result of multimode competition and can manifest itself either through self-pulsing or hysteretic behavior of the bistable type in the laser output intensity and operating frequency. We have verified some of our predictions with the help of a ${\mathrm{CO}}_2$ laser whose observed bistable behavior is in good qualitative agreement with the theoretical predictions.

• Received 3 June 1985

DOI:https://doi.org/10.1103/PhysRevA.33.1842