Open AccessTerahertz polarization spectroscopy in the near-field zone of a sub-wavelength-scale metal slit
Author(s) -
Daehoon Han,
Kanghee Lee,
Hanlae Jo,
Yunheung Song,
Minhyuk Kim,
Jaewook Ahn
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.021276
Subject(s) - optics , terahertz radiation , electric field , polarization (electrochemistry) , terahertz spectroscopy and technology , wavelength , spectroscopy , diffraction , electromagnetic radiation , dipole , materials science , physics , chemistry , quantum mechanics
Time-domain spectroscopy is used to probe the polarization dependence of the terahertz-frequency absorption of α-lactose molecules in the near-field vicinity of a sub-wavelength-scale metal slit. The experimental result finds that the 0.53-THz absorption of this material has an unexpected polarization dependence, strongly coupled to the slit orientation; in particular, the electric wave in parallel polarization exhibits even complete vanishing of the otherwise resonant strong absorption. The physics behind this phenomena may be explained based on the Bethe's sub-wavelength diffraction: the electric field that is measured in the far field, but diffracted from a sub-wavelength-scale metal aperture, originates from solely magnetic dipole radiation and not from the electric dipole radiation, thus showing no electrically-coupled material response.