Synchronization of two strongly pulsating CO₂ lasers

The response of two CO₂ lasers sharing a common saturable absorber when both lasers are strongly pulsating was studied. Both of the lasers behave as strongly nonlinear limit-cycle oscillators exhibiting different amplitudes but similar periods. Since coupling through the saturable absorber is highly nonlinear, communication between lasers occurs only during short periods of time and when they are pulsating at about the same time. Nevertheless, we show experimentally and numerically that in-phase and out-of-phase oscillations are possible modes of synchronization.