Wednesday July 6, 2005
Thursday July 7, 2005

"Plasmon Mediated Excitation of Quantum Dots"
Dr. Matthias Danckwerts
University of Rochester

Surface plasmon polaritons (SPP) are coherent, collective oscillation modes of the electron plasma at a metal surface. Their wave vector lies generally to the right of the light line in a !(k)-plot, hence SPP are usually excited by means of the evanescent field of a totally internally reflected propagating beam (e.g. Kretschmann or Otto configurations), using grating coupling or through fiber coupling. We present here experiments to elucidate a novel way to excite surface plasmon polaritons through nonlinear mixing of multiple photons. In our scheme, two fs-pulsed beams with different wavelengths are focussed to a metal surface such that overlap in time and space is achieved. Depending on the incidence angle of both beams, the energy and momentum conservation requirement for excitation of SPP is met without the need of evanescent fields. Implications of this setup with respect to its application in plasmonics, for example coupling of propagating SPP modes into semiconductor quantum dots, are discussed.