Nonlinear dynamics of optically-injected self-pulsating laser diodes

A numerical analysis is carried out to investigate the influence of injecting either unmodulated or modulated light from an external laser diode (LD) into a 1.55 μm InGaAsP distributed feedback (DFB) self-pulsating (SP) LD. Injection of weak unmodulated light causes the SP-LD to behave mostly chaotically apart from some regions of self-sustained-pulsations (SSP) and multiple-peak periodic oscillations. Increasing the injected optical power has the effects of changing the behavior of the optically-injected SP-LD from chaos to multiple-peak periodic oscillations followed by high-frequency (HF) self-oscillations before reaching an equilibrium state (i.e. a steady level). The SP-LD is found to exhibit quasi-periodic behavior when injected with lightly modulated light. At relatively higher modulation index, the output of the optically-injected SP-LD becomes chaotic