Chaos Synchronization and Spontaneous Symmetry-Breaking in Symmetrically Delay-Coupled Semiconductor Lasers

Abstract

We present experimental and numerical investigations of the dynamics of two device-identical, optically coupled semiconductor lasers exhibiting a delay in the coupling. Our results give evidence for subnanosecond coupling-induced synchronized chaotic dynamics in conjunction with a spontaneous symmetry-breaking: we find a well-defined time lag between the dynamics of the two lasers, and an asymmetric physical role of the subsystems. We demonstrate that the leading laser synchronizes its lagging counterpart, whereas the synchronized lagging laser drives the coupling-induced instabilities.

Semiconductor lasers coupled face-to-face

“…Thus, it can be concluded that the lasers are synchronized on a subnanosecond scale. A similar result was obtained experimentally in the regime of delay times comparable to the relaxation time [3]. In these steps, the difference between the lasers chaotic inputs and chaotic outputs results from the asymmetry caused by the detuning between the lasers.…”

“…It was also shown that an asymmetry in the lasers forms a leading/lagging configuration where the leading laser synchronizes the lagging one, but not the converse [3]. Another property of mutually coupled semiconductor lasers is localized synchronization, where one of the lasers exhibits large amplitude oscillations whereas the other laser exhibits small amplitude oscillations.…”

“…This is no longer true when coupling semiconductor lasers: the delay becomes an essential parameter. This feature, together with the phase-amplitude coupling characteristic of semiconductor lasers, is critical in experiments on synchronized chaos and results in a spontaneous symmetry breaking which appears as a time lag between the dynamics of two identical lasers [2][3][4][5][6].…”

“…This is no longer true when coupling semiconductor lasers: the delay becomes an essential parameter. This feature, together with the phase-amplitude coupling characteristic of semiconductor lasers, is critical in experiments on synchronized chaos and results in a spontaneous symmetry breaking which appears as a time lag between the dynamics of two identical lasers [2][3][4][5][6].It was also shown that an asymmetry in the lasers forms a leading/lagging configuration where the leading laser synchronizes the lagging one, but not the converse [3]. Another property of mutually coupled semiconductor lasers is localized synchronization, where one of the lasers exhibits large amplitude oscillations whereas the other laser exhibits small amplitude oscillations.…”

Amplitude and phase dynamics in oscillators with distributed-delay coupling

“…Our understanding and treatment of various brain pathologies and deficiencies, such as Parkinson's, Alzheimer's and epilepsy, relies heavily on the analysis of synchronization of oscillating neural populations [3][4][5]. Recent work on laser communication networks has extensively used coupled oscillator models to study the dynamics of in-phase or anti-phase and complete chaos synchronization [6][7][8][9][10]. Chimera states, where a network of oscillators splits into coexisting domains of coherent, phaselocked and incoherent, desynchronized behaviour, have also been observed [11][12][13][14][15].…”