Influences Of Incoherent Optical Feedback On The Nonlinear Dynamical Characteristics Of An Optically Injected Semiconductor Laser

Through introducing external perturbation such as optical injection, optical feedback and optoelectronic feedback, the output of semiconductor lasers (SLs) can exhibit plenty of nonlinear dynamics. Nonlinear dynamics of SLs have attracted much attention due to its wide applications such as optical interconnection, optical storage, secure communication and other fields. In the early research stage, one usually focused on the nonlinear dynamic of a SL subject to one perturbation. Recently, For an optically injected SL, after adopting optoelectronic feedback, the complex dynamic behavior of this systems and related applications was reported. Compared with optoelectronic feedback, the SL with incoherent optical feedback which is also insensitivity to optical phase variation has good stability, and the bandwidth limitation is not existed because no electronic devices. Therefore, the nonlinear dynamic characteristics research of a SL with optical injection and incoherent optical feedback will more valuable.In this paper, based on the rate equations describing the SL (the slave laser) with incoherent optical feedback and optical injection from another laser (the master laser) the influences of the feedback strength, injected strength and frequency detuning between the slave laser and the master laser on the nonlinear dynamical characteristics of the slave laser have been investigated. The results show the SL has rich dynamic output characteristics with the injected strength changed, when the feedback strength and frequency detuning is fixed. The SL has the dynamic output characteristics which contain not only period one (PI), period-two (P2), period-four (P4), chaotic (CO) dynamic phenomena in a single perturbation, but also rules pulsing (RP), two-frequency pulsing (P2P), four-frequency pulsing (P4P), quasi-periodic pulsing (QP) and chaotic pulsing (CP). Meantime, it can be seen that there exits different routes to chaos, where two typical pulsing routes are very easy to observed. One is period-doubling pulsing route and the other is quasi-periodic pulsing route. Finally, The nonlinear dynamics characteristics for different incoherence feedback strengths are mapped as a function of the power of the optical injection and the detuning frequency between the injection frequency and the free-running frequency of the unperturbed SL. The result shows: Compared with an optically injected SL without incoherent optical feedback, adding a perturbation of the laser output was more complex. Significant expansion of the chaos region is observed after introducing incoherent optical feedback.