BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Sanjay Khatri\, UVA-Department of Physics\n\n
When a material is exposed to an intense laser field\, the absence of inversion symmetry at the surface can result in the formation \; of a non-linear surface polarization and surface second harmonic (SSH) emission. We find that the SSH yield from a metal ca n be dramatically influenced by the presence of an additional THz field. I n the experiments\, collinear 100fs 780nm laser and 2ps single-cycle THz b eams are focused at grazing incidence along a gold surface. The SSH yield is measured as a function of the THz intensity\, relative laser-THz delay\ , and laser/THz polarizations relative to the surface normal. The yield fr om an optically flat gold mirror increases by as much as a factor of three in the presence of a 20kV/cm THz eld. Interestingly\, the SSH enhancement for the same THz field is as large as a factor of 27 if the gold mirror i s replaced by a gold-coated diffraction grating\, apparently due to either a local THz field enhancement or increased sensitivity of the non-linear polarization to the THz field near grating micro-structures. We are explor ing the use of THz-enhanced SSH emission to characterize the THz-field enh ancement and/or response of micro-structured metal surfaces with other geo metries.
\n DTSTART:20180402T193000Z LOCATION:Physics Building\, Room 204 SUMMARY:THz enhanced Surface Second Harmonic Generation END:VEVENT END:VCALENDAR