Control of unstable steady states in semiconductor lasers by time-delayed feedback methods
Time-delayed feedback methods can be used to control unstable periodic orbits as well as unstable steady states. We present an application of extended time delay autosynchronization introduced by Socolar et al.  to a semiconductor laser system with undamped relaxation oscillations implemented as a model of Lang-Kobayashi-type. We show that the control method is able to enhance the local stability of the lasing fixed point leading to cw-operation by suppression of unwanted intensity pulsations. Due to the self-feedback, multistable behavior can also occur in the form of delay-induced limit cycles and fixed points for certain choices of the control parameters.
 J. E. S. Socolar, D. W. Sukow, and D. J. Gauthier, Phys. Rev. E 50, 3245 (1994).