Defect-mediated turbulence in lasers with injected signals

Tito Arecchi has been a pioneer in the theory and experiments of laser operation and nonlinear dynamics. Lasers with an injected signal are beautiful prototypes for some of the richest dynamical behaviours ever observed in physics. Focusing on the simplest model of a class A laser with injected signal in the presence of transverse diffraction, we describe locked and unlocked states and the mechanisms of instability when decreasing the intensity of the injected signal. An unexpected transition to defect mediated turbulence is demonstrated in the unlocked regime in spite of the presence of the driving frequency of the injection. This optical turbulence state can lead to defect–mediated rogue waves and to a process of crystallisation when the control parameter is reversed.