Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 93: Plasmonics & Nanooptics VI: Near-Field Microscopy and Phenomena
O 93.4: Vortrag
Freitag, 5. April 2019, 11:15–11:30, H8
Polarization in scattering near-field optical microscopy at resonant excitation — •Hamed Aminpour1, Susanne Kehr1, Michael Klopf2, and Lukas Eng1 — 1Technische Universität Dresden, Germany — 2Helmholtz-Zentrum Dresden-Rossendorf, Germany
Scattering-type near-field optical microscopy (s-SNOM) is a promising technique that allows to obtain optical information of samples on the nanometer length scale. Specifically, the response of molecular vibrations, phonons, and excitons in s-SNOM is particularly sensitive to the polarization direction of the incident optical field. To date, most published works focus on out-of-plane polarized s-SNOM at non-resonant excitation, only. Recently, however, excitation and detection of both in- and out-of-plane polarized local fields was demonstrated, by breaking the axial symmetry of the near-field probe [1].
In this presentation, we investigate an elegant alternative in order to achieve in-plane polarized resonant sample excitation of mid-infrared phonon modes [2]. To backup our experiments, we report here on a COMSOL simulation of the scattered near field, investigated by varying the following parameters: Angle and polarization direction of the incident light; tip-sample distance; sample permittivity as a function of wavelength. We compare these results with polarization-dependent s-SNOM measurements on SrTiO3 in the spectral range from 13 to 16 µ m, demonstrating the large potential of polarization-sensitive s-SNOM for the nanoscopic material analysis.
[1] K.-D. Park et al., Nano Lett. 18, 2912(2018)
[2] S. C. Kehr et al., Synchrotron Rad. News 30, 31(2017)