9705403 Citrin This new project is a collaboration between D. Citrin at Washington State and T. Norris at the University of Michigan. It addresses the response of low-dimensional semiconductor structures to sub-picosecond shaped optical pulses. In particular, we will employ tailored optical pulses incident on semiconductor optical microcavities to coherently excite a population of excitons, and then de-excite them on the subpicosecond time scale. We will focus on the ultrafast modulation of the optical nonlinearities of the system due to the control of the exciton population at 100 GHz repetition rates. In addition, in this project we will explore the use of shaped optical pulses in semiconductors to generate tunable terahertz electromagnetic waveforms in quantum wells in the presence and absence of additional externally applied strong electromagnetic fields. Control of the THz waveforms ill be attained using ideas from coherent control and dynamics of optically excited electron-hole wavepackets. %%% This is a new collaboration between D. Citrin, a theorist at Washington State and an experimentalist, T. Norris at the University of Michigan. Laser pulses of extremely short duration will be used to control the behavior of electrons in microscopic semiconductor-based structures. This new project will address, from a fundamental viewpoint, how such short pulses propagate through small semiconductors, and how the electrons respond to the passage of these light pulses. In addition to the contribution to our understanding of the ultimate limits to the response of semiconductors illuminated by very short laser pulses, the results of this project will be useful to identify fast processes in semiconductors that may be employed for the next generation of ultrahigh- speed optical switches for optical-fiber-based communications systems. Other expec ted applications will be in creating new sources of electromagnetic radiation in regions of the spectrum where no or few convenient sources presently exist. ***
