All-Optical Noninvasive Delayed Feedback Control of Semiconductor Lasers

​The stabilization of unstable states hidden in the dynamics of a system, in particular the control of chaos, received much attention in the last years. In this work, a well-known control method called delayed feedback control is applied for the first time entirely in the all-optical domain. A multisection semiconductor laser receives optical feedback from an external Fabry-Perot interferometer. The control signal is a phase-tunable superposition of the laser signal, and provokes the laser to operate in an otherwise unstable periodic state with a period equal to the time delay. The control is noninvasive, because the reflected signal tends to zero when the target state is reached.