Chaos in semiconductor light-emitting devices

Abstract

In this dissertation chaotic behaviors in semiconductor light-emitting devices are reported. It consists of two parts; one is on the periodic chaotic sequence in a driven nonlinear oscillator using a light-emitting diode and the other on the period doubling route to chaos in a directly-modulated laser diode. In the first part a light-emitting diode is used with a resistor and an inductor to realize an optical source exhibiting chaotic behavior. Periodic-chaotic sequence and evolution of return maps in this circuit are described. Models of the circuit are reviewed and the cause of the chaotic behaviors is discussed. By proposing a one-dimensional mapping function and its modification we explained chaotic behaviors in the circuit, such as the periodic-chaotic sequence, evolution of return maps, and self-replicating attractors, etc. In the second part complex chaotic structures in a directly-modulated laser diode are demonstrated. Effects of the spontaneous emission and the noise on the chaotic behavior in the laser diode are also studied. Mechanism for the period doubling bifurcations are accounted for by solving the laser rate equations analytically. Explicit expressions of parameter ranges for period two and period four oscillations are derived by the perturbation method.