Self-sustained pulsations in a quantum-dot laser

We analyze a delay differential equation for the amplitude of the electrical field in order to understand recent experimental observations of low-frequency oscillations in a QD laser. The laser contains no saturable absorber section and exhibits no relaxation oscillations. We investigate the problem both analytically and numerically. We show that there exists a homoclinic bifurcation from a cavity mode that is responsible for the generation of low-frequency pulsating oscillations. We discuss the role of optothermal effects in the formation of the pulsed dynamics.