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Albert Kim

Two-Photon Absorption FROG: measuring white-light continuum pulses, at Conference on Lasers and Electro-Optics (Baltimore, MD), Monday, May 7, 2001
We demonstrate a new type of frequency resolved optical gating using the two- photon-absorption nonlinearity. The resonant enhancement and lack of phasematching re- quirements enable the FROG measurement of ultrashort white-light continuum laser pulses.
Ultrafast Phase Transitions in Semiconductors, at 2000 MRS Fall Meeting (Boston, MA), Tuesday, November 28, 2000:
talk_365.pdf
We present measurements of the dielectric function of various semiconducting materials (c-GaAs, a-GaAs and GeSb thin-films) over a broad energy range (1.5 - 3.5 eV) with a time resolution of 70 fs after the excitation with an ultrashort laser pulse. The time evolution of the dielectric function provides a wealth of information that allows identification and tracking of the electronic and structural dynamics triggered by the pump pulse. At elevated fluence levels all materials undergo a semiconductor to metal transitions.