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Seminar: Wednesday, September 30, 2009 at 3:30 p.m.

Coherent Control of Electrical Current and Terahertz Radiation
Dr. Ki Yong Kim
University of Maryland College Park

Sandwiched between the traditional optical and microwave regimes, far infrared or terahertz (THz) frequency has recently drawn special attention due to its ubiquitous nature, as well as its potential for molecular sensing, biomedical imaging and spectroscopy, security scanners, and plasma diagnostics. For these applications, there is a present and growing need for high-energy, compact THz sources at a tabletop-scale. In this effort, I will present our recent demonstration of high-energy (>5 microjoule), super-broadband (>75 THz) THz radiation generation using a tabletop femtosecond laser [1]. In this scheme, an ultrafast pulsed laser’s fundamental and second harmonic fields are mixed in a gas of atoms or molecules, causing them to ionize. The resulting plasma can generate a directional electron current and simultaneous far-field THz radiation, all coherently controlled by the laser field amplitudes and relative phase. By controlling the relative phase, we can also switch the output energy between THz and harmonics.

Location: Physics Bldg., room 401