Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Terahertz surface plasmon polariton propagation and focusing on
  periodically corrugated metal wires   In this letter we show how the dispersion relation of surface plasmon
polaritons (SPPs) propagating along a perfectly conducting wire can be tailored
by corrugating its surface with a periodic array of radial grooves. In this
way, highly localized SPPs can be sustained in the terahertz region of the
electromagnetic spectrum. Importantly, the propagation characteristics of these
spoof SPPs can be controlled by the surface geometry, opening the way to
important applications such as energy concentration on cylindrical wires and
superfocusing using conical structures.

18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs