Bifurcations and chaos in a semiconductor laser with coherent or noisy optical injection

This paper investigates theoretically the dynamical sensitivity of semiconductor lasers to external optical signals. Bifurcation analysis of ordinary rate equations, describing noise-free lasers with pure coherent external signal, reveals that considerable modifications to the extend and type of externally induced bifurcations and chaos are possible by tailoring of the laser active-medium and resonator configurations. Extending the analysis to stochastic rate equations, which describe lasers with spontaneous emission noise and noisy external signal, reveals further dynamical effects owing to the introduced random fluctuations. In particular, phase-fluctuations (incoherence) in the external signal can have a dramatic impact on induced bifurcations and chaos. The observed strong sensitivity of laser instabilities to the intensity and coherence of external signal can provide a very sensitive means to detect ultra low levels of laser radiation.