Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 54: Nano-optics of metallic and semiconducting nanostructures (experiments II)
O 54.10: Vortrag
Donnerstag, 26. März 2009, 17:15–17:30, SCH A216
Phase contrast imaging in near-field superlensing — •Thomas Taubner1,2, Jon Schuller2, Mark Brongersma2, Chris Fietz3, Gennady Shvets3, and Rainer Hillenbrand4 — 1I. Physikalisches Institut, RWTH Aachen, Germany — 2Department of Material Science, Stanford University, USA — 3Department of Physics, UT Austin, USA — 4Max-Planck-Institut für Biochemie, Martinsried, Germany
Here we study the optical imaging properties of novel near-field imaging device called a SiC superlens. A superlens is a planar device that allows for subwavelength imaging by employing coupled surface waves on a thin slab of a negative-permittivity material. As opposed to previous intensity-only measurements, we now perform amplitude and phase-measurements of the near-fields in the image plane of a superlens by mapping the field distribution with a scattering-type near-field optical microscope (s-SNOM). When investigating the spectral properties of the SiO2/SiC/SiO2 superlens, we observe a sign change in the phase of the transmitted near-fields when tuning the illumination wavelength over the superlenses resonance condition.
This change will be explained by the dispersion relation of the superlens, in combination with a fundamental interference effect. When operating a superlens off-resonance, the interference of evanescent fields causes the intensity contrast to decrease. This can be compensated for with phase-sensitive imaging to practically maintain the spectral range of high-resolution operation. Our results are important for future spectroscopic applications of superlenses and other devices such as hyperlenses or 2D plasmon lenses.