Performance characteristics of positive and negative delayed feedback on chaotic dynamics of directly modulated InGaAsP semiconductor lasers

The chaotic dynamics of directly modulated semiconductor lasers with delayed optoelectronic feedback is studied numerically. The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum value range is investigated using bifurcation diagrams. The results are confirmed by calculating the Lyapunov exponents. A negative delayed optoelectronic feedback configuration is found to be more effective in inducing chaotic dynamics to such systems with nonlinear gain reduction factor in the practical value range.Comment: 18 pages, 16 figures. To appear In Pramana - journal of physic

Periodic Orbits and Topological Entropy of Delayed Maps

The periodic orbits of a nonlinear dynamical system provide valuable insight in the topological and metric properties of its chaotic attractors. In this paper we describe general properties of periodic orbits of dynamical systems with feedback delay. In the case of delayed maps, these properties enable us to provide general arguments about the boundedness of the topological entropy in the high delay limit. As a consequence, all the metric entropies can be shown to be bounded in this limit. The general considerations are illustrated in the cases of Bernoulli-like and H'enon-like delayed maps. PACS number(s): 05.45.-a, 05.45.Jn I. INTRODUCTION As the mechanism of retarded feedback is present in almost all situations associated to finite propagation times, delayed differential equations of the form Eletronic Address: [email protected] 1 ~x = ~ F (~x(t); ~x(t \Gamma )) (1) are largely employed to model control processes in the nature and technology. Examples of suc..