Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 66: Plasmonics and Nanooptics VI
O 66.7: Vortrag
Donnerstag, 17. März 2011, 12:45–13:00, WIL A317
Investigation of polarization effects in reconstruction of highly focused vector beams using the knife-edge method — •Christian Huber1,2, Pavel Marchenko1,2, Sergejus Orlovas1,2, Peter Banzer1,2, Ulf Peschel2, and Gerd Leuchs1,2 — 1Max Planck Institute for the Science of Light, Günther-Scharowsky-Str. 1, D-91058 Erlangen — 2Institute of Optics, Information and Photonics, University Erlangen-Nuremberg, Staudtstr. 7/B2, D-91052 Erlangen
For experiments with highly focused vector beams the focal field distribution has to be known. The knife-edge method can be used to reconstruct the intensity distribution of the electric field in the focal plane of a high NA objective. For that purpose, a thin knife-edge fabricated on a photodiode is moved through the focal spot while the photocurrent is recorded. To calculate the beam profile by inverse Radon transform the measurements have to be performed for different angels from 0 to 180 degrees of the edge relative to the beam. As demonstrated previously [1] the focal spot can be experimentally characterized at a wavelength of 633 nm using a special mixture of Zink and Gold as knife-edge material. However for pure materials the reconstructed field distribution is modified by polarization dependent effects. To investigate these effects in detail we performed measurements for different edge materials, edge thicknesses and for different wavelengths. According to our experimental and theoretical results the observed polarization dependency for pure materials is caused by effects such as the excitation of plasmonic modes. [1] R. Dorn et al., Opt., 50 (12), 1917-1926 (2003)