Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical absorbers based on strong interference in ultra-thin films   Optical absorbers find uses in a wide array of applications across the
electromagnetic spectrum, including photovoltaic and photochemical cells,
photodetectors, optical filters, stealth technology, and thermal light sources.
Recent efforts have sought to reduce the footprint of optical absorbers,
conventionally based on graded structures or Fabry-Perot-type cavities, by
using the emerging concepts of plasmonics, metamaterials, and metasurfaces.
Unfortunately, these new absorber designs require patterning on subwavelength
length scales, and are therefore impractical for many large-scale optical and
optoelectronic devices.
  In this article, we summarize recent progress in the development of optical
absorbers based on lossy films with thicknesses significantly smaller than the
incident optical wavelength. These structures have a small footprint and
require no nanoscale patterning. We outline the theoretical foundation of these
absorbers based on "ultra-thin-film interference", including the concepts of
loss-induced phase shifts and critical coupling, and then present several
applications, including ultra-thin color coatings, decorative photovoltaics,
high-efficiency photochemical cells, and infrared scene generators.

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The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
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The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph