Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 39: Focus Session: Phonon Polaritons: Opportunities for THz Nanooptics II
O 39.6: Talk
Tuesday, March 13, 2018, 15:15–15:30, HE 101
Towards nanoscale time-domain-spectroscopy at low-repetition-rate terahertz sources — •Thales V. A. G. de Oliveira1,2, Frederik Kuschewski1, Sergey Kovalev1, Eduardo J. H. Lee3, Nilesh Awari1, Bert Green1, Susanne C. Kehr2, Michael Gensch1, and Lukas M. Eng2 — 1Helmholtz-Zentrum Dresden-Rossendorf. Bautzner Landstraße 400, D-01328 Dresden — 2Technische Universität Dresden. Nöthnitzer Straße 61, D-01187 Dresden — 3. Universidad Autónoma de Madrid. Calle Francisco Tomás y Valiente 7, E-28049, Madrid
Nanoscopy in the deep THz regime is particularly interesting as the interactions leading to THz resonances, absorption or emission (i.e. interactions of spins, lattice, and charge carriers) are occurring on a much smaller length scale as compared to the wavelengths of the corresponding electro-magnetic fields. As the tool of choice, scattering-type scanning near field optical microscopy (s-SNOM) at THz wavelengths was previously demonstrated with superb spatial resolution when operated in the time domain. In this talk we report on the implementation of s-SNOM for time-domain-spectroscopy and nanoimaging near or even under the Nyquist-Shannon sampling limit, using broadband table-top sources and a unique accelerator-based super-radiant THz light source at low-repetition-rate (1 - 200 kHz). Operation at low repetition rates is of great importance for a variety of pump-probe experiments, which require THz probing at few 100 kHz or lower, since the typical recovery time after optical excitation in many interesting material systems can be on the order of a few µ s.