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A: Atomphysik

A 19: Wechselwirkung mit VUV and X-FEL Licht

A 19.1: Hauptvortrag

Donnerstag, 16. März 2006, 14:00–14:30, H7

Nonlinear Optics in Coherently Prepared Media — •Thomas Halfmann — Fachbereich Physik, Technische Universitaet Kaiserslautern, Erwin-Schroedingerstrasse, 67653 Kaiserslautern

Nonlinear optics provide a powerful tool to extend the wavelength regime of coherent radiation. In particular, short-wavelength, i.e. vacuum- (VUV) or extreme ultraviolet (XUV) radiation, is of significant interest for lithography, high-resolution microscopy or spectroscopy. Atomic gases exhibit typical nonlinear optical media to drive frequency conversion processes to the VUV or XUV. However, nonlinear optical processes in gaseous media suffer from low conversion efficiencies. Coherent preparation of the media, adiabatically driven by laser pulses with moderate intensities, serves to overcome these difficulties and permits the significant enhancement of frequency conversion processes. The talk reports on enhancement of four-wave mixing in media, prepared in maximum coherence by Stark-chirped rapid adiabatic passage (SCRAP). The efficiency of the frequency conversion processes, yielding VUV and XUV radiation, is enhanced by more than one order of magnitude with respect to the case of conventional frequency conversion. Even less efficient preparation of coherences, induced by ultra-short radiation pulses, permits the significant enhancement of frequency conversion. The generation of coherent ultra-broad spectra in molecular systems is strongly enhanced by stimulated coherences. Thus, these results demonstrate the significant potential of coherent preparations in nonlinear optical media paving the way towards enhanced sources for coherent radiation.