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_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.

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All-Optical Control Setup.- Stable States with Resonant Fabry-Perot Feedback.- Control of an Unstable Stationary State.- Control of Unstable Self-Pulsations.- Controlling Chaos.- Control of a Torsionfree Orbit.

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Dr. Sylvia Schikora completed her doctoral thesis on ultrafast noninvasive control of semiconductor lasers at the Department of Physics, Humboldt University of Berlin. She currently works at Humboldt University as a postdoctoral researcher with a focus on optical metrology.

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