Proposal Number: ECS-9625532 Principal Investigator: Mansoor Sheik-Bahae CAREER: Investigation of Femtosecond Dynamics and Optical Switching in Active Semiconductors The principal goal of this research is to investigate the feasibility of ultrafast all-optical switching in semiconductor laser amplifiers waveguides Data transmission networks must adapt to ever increasing demand for high transmission capacity. Although optical fibers provide a large usable bandwidth (30 terabits/sec) a serious limitation on system bandwidth has been imposed by the current electronics switching (less than 10 gigabits/sec). Active semiconductors can be a key technology to break this bottleneck. Very large and fast nonlinearities have been recently discovered in active semiconductor laser diodes, which are based on fundamental processes inherently different form those of the passive semiconductors used heretofore. This research will further develop and exploit the nonlinear optical properties of active semiconductor lasers within the context of development of a practical ultrafast switching device. The following fundamental studies will be carried out: measurements of gain and refractive nonlinearities in semiconductor laser amplifiers as function of wavelength, current density and temperature, and design of an optical switch in an active directional coupler geometry. Then, optical switches will be fabricated by the Center for High Technology Materials at the University of New Mexico and their performance tested. Successful completion will have direct implications for faster exchange of data in fiber-optic communications networks and for the national leadership of the U.S. in the important area of electro-optic communications.