Institut Photonique

As optical communication technologies move toward fully light-based architectures, unconventional beams offer new opportunities for advanced control of light propagation and information processing. Airy beams, in particular, are notable for their self-bending trajectories and resistance to diffraction. In this study, we explore how these beams evolve nonlinearly when propagating through optically induced photonic lattices with defects. By conducting a detailed analysis, we show that the interplay between beam parameters, lattice design, and nonlinear effects governs the number, position, and intensity of the resulting output channels. Our investigation reveals that fine adjustments of these factors allow not only the creation of multiple stable output pathways but also control over their spacing. These insights underscore the relevance of defect-tailored lattices combined with Airy beam excitation for optical routing and interconnects, contributing to the development of adaptable all-optical processing systems.

Vertical-cavity surface-emitting lasers (VCSELs) can exhibit chaotic dynamics even in free-running operation due to mode competition. While most studies have focused on single-mode VCSELs, we numerically investigate multimode VCSELs including higher-order transverse modes. The emergence of these modes introduces additional bifurcations at higher pump currents, producing complex dynamics and polarization mode competition consistent with recent experiments. We show that the chaotic dynamics originates from the interplay between the undamped dynamics at the relaxation oscillation frequency and the self-pulsation at the birefringence frequency. Furthermore, we observe a novel dynamic termed transverse mode hopping (TMH) where different transverse modes with the same polarization exhibit a strongly anticorrelated dynamics. Interestingly, under certain conditions, the multimode VCSEL exhibits less complex dynamics than the single-mode one, even reaching a stationary state after a chaotic regime. Our numerical findings are in good qualitative agreement with recent experiments.

Optical injection (OI) is a well-established technique for stabilizing laser frequency and linewidth or for inducing nonlinear dynamics. When optical feedback (OF) is added, the injection-locking (IL) region is strongly modified and richer dynamics emerge. While theory predicted that OF can induce an oscillatory IL boundary, this had not been confirmed experimentally. We report the first experimental observation of a quasiperiodic cascade in a laser diode under simultaneous OI and OF. The feedback delay (τ = 0.5 ns) corresponds to an external-cavity frequency of 2 GHz. As the injection frequency is tuned, the laser alternates between periodic and quasiperiodic regimes, in excellent agreement with recent numerical predictions [1]. Two distinct scenarios arise depending on whether the feedback operates in the short- or long-cavity regime. These results provide experimental evidence of feedback-induced cascades and clarify the complex boundaries of injection locking in semiconductor lasers. [1] Oliverio, Rontani & Sciamanna, Opt. Express 32, 25906 (2024).