Localized states, self-pulsing and excitability in VCSELs and microlasers with saturable absorber

Abstract

We present experimental and theoretical results on Vertical Cavity Surface Emitting Lasers (VCSELs) and microlasers with saturable absorber. Laser cavity solitons are experimentally demonstrated in a compact system, a broad-area VCSEL with intracavity saturable absorber. These states of light appear as 10 μm diameter self-localized microlasers that one can manipulate with external beams in the transverse plane of the laser. Cavity solitons (CS) can be thought of as optical bits for reconfigurable processing of information. We demonstrate incoherent manipulation of CS at a fast rate and present evidence of optical manipulation of self-pulsing states. Excitability is also demonstrated in a different parameter region. Excitability is characterized by: 1) existence of a threshold leading to an “all or nothing” type of response to an input perturbation, 2) appearance of a calibrated response above threshold. Excitable response is interesting for optical pulse reshaping and may be used to build logical gates. A chain of such coupled microlasers can also be used to demonstrate discrete nonlinear wave propagation, with application to e.g. optical delay lines or neuro-inspired processing. A novel scheme to attain self-pulsing in nanocavity lasers will also be presented, thus showing the possible scaling down of the previous system.