Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Refracting Metasurfaces without Spurious Diffraction   Refraction represents one of the most fundamental operations that may be
performed by a metasurface. However, simple phasegradient metasurface designs
suffer from restricted angular deflection due to spurious diffraction orders.
It has been recently shown, using a circuit-based approach, that refraction
without spurious diffraction, or diffraction-free, can fortunately be achieved
by a transverse metasurface exhibiting either loss-gain or bianisotropy. Here,
we rederive these conditions using a medium-based - and hence more insightfull
- approach based on Generalized Sheet Transition Conditions (GSTCs) and surface
susceptibility tensors, and experimentally demonstrate two diffraction-free
refractive metasurfaces that are essentially lossless, passive, bianisotropic
and reciprocal.

27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
7
The categories of this paper are: hep-th