Regenerative vectorial breathers in a delay-coupled excitable microlaser with integrated saturable absorber

We report on the polarization dynamics of regenerative light pulses in a micropillar laser with an integrated saturable absorber (SA) coupled to an external feedback mirror. The delayed self-coupled ML is operated in the excitable regime, where it regenerates incident pulses with a supra-threshold intensity—resulting in a pulse train with an inter-pulse period approximately given by the feedback delay time, in analogy with a self-coupled biological neuron. We report the experimental observation of regenerative vectorial breathers (RVBs) in a polarization angle, manifesting themselves as a modulation of the linear polarized intensity components without a significant modulation of the total intensity. A numerical analysis of a suitable model reveals that the observed polarization mode competition is a consequence of symmetry-breaking bifurcations induced by polarization anisotropy. Our model reproduces well the observed experimental results and predicts different regimes as a function of the polarization anisotropy parameters and the pump parameter. We believe that these findings are relevant for the fabrication of flexible sources of polarized pulses, as well as for neuroinspired on-chip computing applications.