Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: Plasmonics and Nanooptics VI

O 72.5: Talk

Thursday, March 25, 2010, 16:00–16:15, H32

Free-Space Excitation of Propagating Surface Plasmon Polaritons — •Jan Renger¹, Romain Quidant¹, Niek van Hulst¹, Stefano Palomba², and Lukas Novotny² — ¹ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels (Barcelona), Spain — ²Institute of Optics, University of Rochester, Rochester, NY 14627, USA

A unique feature of surface plasmon polaritons (SPPs) is that their in-plane momentum is larger than the momentum of free-propagating photons of the same energy. Therefore, it is believed that they can be excited only by evanescent fields created by total internal refection or by local scattering. Here, we provide the first demonstration of free-space excitation of surface plasmons by means of nonlinear four-wave mixing [1]. The process involves the vectorial addition of the momenta of three incident photons, making it possible to penetrate the light cone and directly couple to the SPP dispersion curve. Using this technique, surface plasmons can be launched on any metal surface by simply overlapping two beams of laser pulses incident from resonant directions. The excitation scheme is also applicable to other bound modes, such as waveguide modes, surface phonon-polaritons, and excitations of two-dimensional electron gases. [1] J. Renger et al. Phys. Rev. Lett. accepted (2009)