Localized Structures in Dissipative Nonlinear Systems - Abstract

Tissoni, Giovanna

Spontaneous and induced motion of cavity solitons in different semiconductor systems and their applications

In a vertical cavity semiconductor laser with an intracavity saturable absorber, cavity solitons (CS) behave as localized micro-lasers sitting over a zero-intensity, non-lasing background, thus realizing a cavity soliton laser (CSL). We show that in this system there are parametric conditions for which the CS moves spontaneously in the transverse plane, with a velocity of the order of some μm/ns, depending on the parameters of the system. A key parameter ruling the dynamical instability causing CS motion is the ratio between the non-radiative decay rates of carriers belonging to the active and passive media. Interesting effects arise when the pump profile is not infinite and homogeneous and the translational symmetry of the system is broken. For example, if the pump has a circular profile, the CS moves along the boundary. On the other hand, for a square pump profile the CS bounces against the boundaries, with a non-Newtonian reflection law. If more than one moving CS are present, repulsive or destructive collisions are observed. Interactions with material defects are also under investigation, giving rise to different dynamical behaviors: depending on the parameters of the system, both attracting and repulsive interactions are found. We also show that CS in models of VCSELs with optical injection have properties like stability, gradient-induced drifting with controlled speed, and pair-merging that are important in optical memories and delay lines. In particular we demonstrate large velocities of CS propagation in the transverse space due to an injected frequency tuning and 2D CS merging in the presence of modulated injected phase for the optimization of memory operations.