EXPERIMENTAL CONTROL OF INSTABILITIES AND CHAOS IN FAST DYNAMICAL SYSTEMS

I investigate experimentally and theoretically the application of control techniques in systems that display temporal instabilities, including chaos, on very short timescales. My study includes two distinct systems: a fast chaotic electronic circuit called the diode resonator, and a compound-cavity semiconductor laser system that exhibits an instability called low-frequency ßuctuations. Control of fast unstable systems presents several experimental challenges. It is also a topic of broad interest, since it requires the development of new control techniques, and addresses technologically important devices such as the semiconductor laser. The diode resonator is a well-understood system, and when modiÞed for 10 MHz operation serves as a good testbed for the application of novel control techniques. I develop a new high-speed time-delay feedback control technique that is based on the comparison of the present value of a system variable with a series of its past values. The principles of operation of this technique are studied in both time and frequency domains, as well as possible methods for its implementation. I develop