Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Plasmonics and Nanooptics III
O 28.6: Vortrag
Dienstag, 15. März 2011, 12:30–12:45, WIL A317
scattering near-field microscopy in the THz using a free-electron laser — •Hans-Georg von Ribbeck1, Marc Tobias Wenzel1, Rainer Jacob2, and Lukas M. Eng1 — 1Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden, Germany — 2Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany
We present scattering-type scanning near-field optical micro spectroscopy (s SNOM) investigations successfully operated in the THz range with a wavelength independent spatial resolution of 90 nm. Our microscopy set-up bases on a true noncontact atomic force microscope (nc-AFM) combined with the free-electron laser (FEL) source at the Helmholtz-Zentrum Dresden-Rossendorf. This laser provides tunability from 30 to 250 µm. We were able to record, for the first time ever, s-SNOM signatures with a FEL at wavelengths ranging from 30 µm to 180 µm (10 to 1.67 THz). In addition to the near-field dependent optical signals we also demonstrate the imaging and spectroscopy capabilities of our THz-s-SNOM. Image scans were performed on a specially designed test structure consisting of a topography-free composite of a polymer/gold sample. On these samples a topography independent strong optical material contrast could be demonstrated at 150 µm wavelength. Furthermore we achieve a resolution of better than 90 nm on a Fischer-Pattern test structure, corresponding to an optical improvement of better than 1500 times the wavelength.