NASA STI/Recon Technical Report N
Excitonic Bistabilities, Instabilities and Chaos in Laser-pumped Semiconductors
Nguyen Ba An, Dan Trung Nguyen, Hoang Xuan Nguten
Abstract
Abstract The Hurwitz criteria are used for a stability analysis of the steady state excitonic optical bistability curves in a semiconductor pumped by an exter- nal laser resonant with the exciton level. Besides the middle branch of the bistability curves which is unstable in the sense of the linear stability theory, we have found other domains of instability in the upper and lower branches of the steady state curves. Numerical results show that a possible route to chaos in the photon-exciton system is period-doubling self- oscillation process. The influence of the presence of free carriers that coexist with the excitons is also discussed. 1. Introduction Stability and instability are two sides of matter which are by no means independent but closely related. For example, in case the system state curve develops three branches, it is the unstable behaviour of the middle branch that causes a jumping up or down to the upper or lower branches thus generating the effect of bistability. Bistable devices them- selves may in turn manifest a rich variety of instabilities leading to spontaneous pulsations of both regular and irregular nature. Since 1987 a fully new direction of research dealing with optical self-pulsing and chaos has been orient- ed by the original works of McCall [l], Bonifacio and Lugiato