Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-Invasive Near-field Spectroscopy of Single Sub-Wavelength
  Complementary Resonators   Subwavelength metallic resonators provide a route to achieving strong
light-matter coupling by means of tight confinement of resonant electromagnetic
fields. Investigation of such resonators however often presents experimental
difficulties, particularly at terahertz (THz) frequencies. A single
subwavelength resonator weakly interacts with THz beams, making it difficult to
probe it using far-field methods; whereas arrays of resonators exhibit
inter-resonator coupling, which affects the resonator spectral signature and
field confinement. Here, traditional far-field THz spectroscopy is
systematically compared with aperture-type THz near-field microscopy for
investigating complementary THz resonators. Whilst the far-field method proves
impractical for measuring single resonators, the near-field technique gives
high signal-to-noise spectral information, only achievable in the far-field
with resonator arrays. At the same time, the near-field technique allows us to
analyze single resonators - free from inter-resonator coupling present in
arrays - without significant interaction with the near-filed probe.
Furthermore, the near-field technique allows highly confined fields and surface
waves to be mapped in space and time. This information gives invaluable insight
into resonator spectral response in arrays. This near-field microscopy and
spectroscopy method enables investigations of strong light-matter coupling at
THz frequencies in the single-resonator regime.

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The categories of this paper are: hep-lat
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: astro-ph