Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Plasmonics and Nanooptics IV

O 41.6: Talk

Wednesday, March 16, 2011, 12:30–12:45, WIL A317

Spatiotemporal nanofocusing in random nanostructures achieved by time-reversal, adaptive optimization, and optimal open-loop control of ultrashort laser pulses — •Dominik Differt¹, Javier Garcia de Abajo², Christian Strüber¹, Dmitri Voronine^1,3, and Walter Pfeiffer¹ — ¹Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany — ²Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain — ³Department of Physics, Texas A&M University, 4242 TAMU, College Station, USA

Because of the reciprocity of electromagnetic wave propagation the time-reversal of a wave emitted from a nanoemitter embedded in a random scattering environment should refocus in space and time at the emitter site. If only partial waves, e.g. one particular planar wave component, of the outgoing wave are time-reversed this nanolocalization of the back-propagated wave is not perfect. Here we investigate the degree of spatiotemporal nanolocalization of time-reversed partial planar waves. The chosen nanostructure consists of two nanoemitter particles embedded in a random assembly of metallic nanospheres acting as scattering environment. A multiple elastic scattering of multipole expansion (MESME) code is used for solving Maxwell's equations in frequency domain. The degree of nanolocalization varies significantly and depends critically on which partial planar wave is time-reversed. In addition, direct adaptive optimization or optimal open-loop control of the spatiotemporal nanofocusing of planar waves at the emitter position exhibits a much higher degree of nanolocalization.