Nonlinear Dynamics in Semiconductor Lasers - Abstract
Panayotov, Krassimir
In this communication, we first demonstrate experimentally and theoretically the vectorial character of cavity solitons in semiconductor laser when varying the direction of linearly polarized holding beam. We have built an experimental setup for generation and characterization of localized structures in the transverse section of a broad area VCSEL. Bistability corresponding to the spontaneous appearance and disappearance of a localized structure has been observed, as a function of optical injection power. The Stokes parameters of these localized structures have been measured, for orientations of the optical injection linear polarization varying in a 90° span. Our measurements show that the cavity soliton polarization state is not exactly the one of the optical injection but acquires distinct ellipticity. Theoretically, we use the spin-flip VCSEL model to study such vector localized structures. Cavity solitons, numerically generated using this model, present an ellipticity comparable to the one found in the experiment. We also carry out detailed mapping of the steady states and their stability in the plane of injection strength-frequency detuning between optical injection and VCSEL. We generalize models of VCSEL with a saturable absorber to account for the polarization degree of freedom and investigate its impact on the cavity soliton dynamics for such system. Next, we study the effect of delayed feedback on the cavity soliton mobility properties. We present analytical and numerical analysis of the dependence of the drift instability threshold and on the feedback strength, feedback phase, and carrier relaxation time. In particular we demonstrate that due to finite carrier relaxation rate the delay induced drift instability can be suppressed to a certain extent. We give analytical estimation of the soliton velocity near the drift instability point which is in a good agreement with numerical results obtained using the full model equations. For the case of VCSEL with a saturable absorber we demonstrate a period doubling route to chaos of a single localized structure and investigate the bifurcation route to chaotic dynamics.