Dynamical behaviors of vertical-cavity surface-emitting lasers with an embedded saturable absorber subjected to an on-off keying (OOK) current modulation

We numerically study the dynamics of VCSEL-SA when modulated by an analog on-off keying (OOK) current. It is found that the laser gives a pulse-like response when operated below the threshold current. After the threshold current, which is in the excitable phase, the laser generates single spikes (phasic spiking) and a series of spikes (tonic spiking) wherein the amplitude of the spikes varies as the form of the current. Complex dynamics such as bursting oscillations and chaotic dynamics are successfully generated at low frequencies (few MHz). After this excitable phase, the laser copies the OOK current with underdamped oscillations generated during the OFF phase of the OOK current.