Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Metamaterial near-field sensor for deep-subwavelength thickness
  measurements and sensitive refractometry in the terahertz frequency range   We present a metamaterial-based terahertz (THz) sensor for thickness
measurements of subwavelength-thin materials and refractometry of liquids and
liquid mixtures. The sensor operates in reflection geometry and exploits the
frequency shift of a sharp Fano resonance minimum in the presence of dielectric
materials. We obtained a minimum thickness resolution of 12.5 nm (1/16000 times
the wavelength of the THz radiation) and a refractive index sensitivity of 0.43
THz per refractive index unit. We support the experimental results by an
analytical model that describes the dependence of the resonance frequency on
the sample material thickness and the refractive index.

37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci