COUPLED SEMICONDUCTOR LASERS AND MACKEY-GLASS ELECTRONIC CIRCUITS

We describe two experimental systems where a time-delayed feedback mech-anism plays an important role in inducing instabilities. The first system consists of two cross-coupled semiconductor lasers with time-delayed negative optoelectronic feedback. This system is described by coupled delay-differential equations, and we explore the dynamics near the onset of oscillations as the coupling strength is varied. We study the influence of asymmetric coupling strengths on the onset of oscillations and the dependence of the amplitudes of oscillations on the coupling strengths. In-phase oscillations with a period of twice the delay time emerge as the product of coupling strengths increases above a critical value. A scaling relationship is ob-served between rescaled amplitudes of oscillations and the product of the coupling strengths. We also study the dependence of the periodicity and the phase relations of the oscillations as we adjust the delay time. The second system is an electronic circuit with time-delayed nonlinear feed-back which simulates the Mackey-Glass model described by a delay-differential equa-tion. First we study the dynamics of the Mackey-Glass system in various parame