Taming chaos in semiconductor lasers subject to optical feedback

In most encounters, chaotic behavior is considered a nuisance, if not a down right detriment to system performance, especially in laser devices. Often, much time and effort is spent in search of finding ways to eliminate or suppress the sources of chaos. However, within the last couple of years it has been recognized that chaos in a system can serve as a rich source of complex frequencies which one can access and easily switch between. The algorithm for locking the system into one of these frequencies was put forth in the pioneering paper by Ott, Grebogi, and Yorke in 1990. Since then there has been a flurry of both theoretical activity to refine the techniques used for controlling chaos and experimental efforts demonstrating control of chaos in various systems. Although, there now appears in the literature several algorithms for controlling chaos, they are essentially minor variants of the original ideas of the Ott, Gregobi and Yorke, or the OGY scheme as it has come to be known. At the Nonlinear Optics Center we are interested in the practical applications of controlling chaos to laser systems, in particular semiconductor diode lasers. By using the ideas of controlling chaos, we hope to be able to stabilize large arrays of coupled semiconductor diode lasers in regimes in which they would ordinarily be chaotic. A discussion of problems related to implementing the controlling algorithm in an experiment currently being conducted at the Phillips Laboratory is presented