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Q: Quantenoptik und Photonik
Q 42: Ultrakurze Lichtimpulse: Carrier-Envelope-Phase
Q 42.5: Vortrag
Donnerstag, 25. März 2004, 17:30–17:45, HS 223
Spatial and temporal control of optical near field distributions using femtosecond polarization pulse shaping — •W. Pfeiffer1, F.J. Garcia de Abajo2, and T. Brixner3 — 1Universität Würzburg, Physikalisches Institut EP1, 97074 Würzburg, Germany — 2Centro Mixto CSIC-UPV/EHU, 20080 San Sebastian, Spain — 3University of California at Berkeley, Department of Chemistry, Berkeley, CA 94720, USA
Optical near-field distributions are at the center of experimental techniques such as scanning photon tunneling microscopy (STM) or near-field two-photon fluorescence microscopy. Ultrahigh spatial resolution is provided by making use of the optical field enhancement in the vicinity of a sharp tip. We simulate the field distribution near an STM tip/sample geometry under the irradiation with polarization-shaped femtosecond laser pulses by means of the boundary-element method. This allows for the first time to shape all three mutually orthogonal polarization components of a femtosecond light pulse in a complex fashion. Using an evolutionary algorithm, nonlinear signals and contrast ratios at specific points in space can be enhanced by optimized light pulses. Apart from applications in the above-mentioned near-field techniques, this offers the possibility for three-dimensional quantum control on surface-adsorbed molecules, accessing 3D wavefunction properties with light fields optimized in all three polarization directions and along three spatial coordinates.