Mode-mode competition and unstable behavior in a homogeneously broadened ring laser

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 CO₂ laser whose observed bistable behavior is in good qualitative agreement with the theoretical predictions.