Wednesday, September 7, 2016

Abstract-Terahertz polarization spectroscopy in the near-field zone of a sub-wavelength-scale metal slit

Daehoon Han, Kanghee Lee, Hanlae Jo, Yunheung Song, Minhyuk Kim, and Jaewook Ahn

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.
© 2016 Optical Society of America
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