Wideband complex-enhanced chaos generation using a semiconductor laser subject to delay-interfered self-phase-modulated feedback

A wideband complexity-enhanced chaos generation scheme is proposed by using semiconductor laser subject to delay-interfered self-phase-modulated optical feedback. The influences of feedback strength, phase modulation index and interference delay on the effective bandwidth and time-delay-signature (TDS) characteristics of the proposed scheme-generated chaos are extensively investigated both experimentally and numerically. The results demonstrate that with the joint effects of phase modulation-induced spectrum expansion and nonlinear filtering of delayed interference, wideband chaos with flat spectrum and excellent TDS suppression characteristics can be generated over a wide dynamic operation range. In comparisons with the relevant chaos generation schemes under convention optical feedback, individual self-phase modulated optical feedback, and delay-interfered optical feedback, the proposed scheme can not only significantly enhance the effective bandwidth of chaos, but also considerably enhance the complexity of chaos by suppressing the TDS towards a distinguishable level close to 0.