Abstract

Excitability is a very generic feature of several kinds of nonlinear dynamical systems (including biological and optical ones) defined by the threshold-like response of the system to external perturbations. In particular, the excitable character of a laser with saturable absorber has been demonstrated both theoretically and experimentally in absence of any spatial degree of freedom [1]. On the other hand, a semiconductor laser with saturable absorber with sufficiently high transverse extension is known to support the formation of localized structures [2]. These two considerations naturally raise the question of the existence of excitable localized states: can the excitable character of the system still be present in a parameter range corresponding to transverse localization? Even if excitability mediated by localized structures has been observed numerically in a model of a dissipative (Kerr) nonlinear optical cavity [3], no experimental observation of excitability has been reported to date in spatially extended optical systems. We therefore explore the dynamical regimes exhibited by a system consisting of two coupled semiconductor lasers in an absorber-amplifier configuration, a system known to host localized states [4].

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