TITLE: Strongly Driven Semiconductors

SPEAKER: Dr. Alan Chin,

As electronic switching times approach terahertz frequencies, the distinction between electronics and photonics becomes less well defined and signals will be increasingly transmitted via optics. Therefore, understanding the coupling between light beams will become increasingly important for future optoelectronics. Our approach to studying phenomena in this future regime of optoelectronics is to study the interaction of lower frequency mid-infrared (MIR) or far-infrared light with near-infrared light in semiconductors. Using intense MIR pulses as a strong driving field, we have observed significant induced absorption below the band gap in semiconductors . The effect occurs when the magnitude of the MIR electric field is such that the ponderomotive potential (average kinetic energy of an electron in an AC electric field) is comparable to the photon energy of the applied field. Under such strong driving fields, we also observed the generation of multiple off-resonance optical sidebands in semiconductors and multiple harmonics of the driving field.