Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Poster Session: Matter at Low Temperature
TT 11.8: Poster
Montag, 14. März 2011, 14:00–18:00, P4
Coherent broadband continuous-wave THz spectrometer: Implementation at low temperature and high magnetic field — •Malte Langenbach1, Komalavalli Thirunavukkuarasu1, Andreas Janssen1, Holger Schmitz1, Iván Cámara Mayorga2, Rolf Güsten2, Axel Roggenbuck3, Anselm Deninger3, Markus Grüninger1, and Joachim Hemberger1 — 1II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany — 2Max-Planck-Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Germany — 3TOPTICA Photonics AG, Lochhamer Schlag 19,D-82166 Gräfelfing, Germany
Our high-resolution THz spectrometer employs photomixing of two NIR-DFB diode lasers for generation and phase sensitive detection of THz radiation of frequency from 60 GHz to 1.8 THz. A fiber-based phase modulation allows simultaneous determination of THz amplitude and phase. The two photomixers (the source and the detector) offer a compact face-to-face spectrometer assembly. Recently, this assembly was successfully integrated in the commercial magnetic cryostats. The initial problem of a low temperature resistant coupling between laser fibers and photomixers was overcome with a better design. We will present some first results to illustrate the properties of our setup and the response of the antennas for different temperatures down to 3 K and magnetic fields up to 8 T. The integrated setup enables phase sensitive broadband transmission spectroscopy in the subphonon regime at low temperatures and in high magnetic fields facilitating the study of low energy excitations in complex materials.