Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ewald sphere construction for structural colors   Disordered structures producing a non-iridescent color impression have been
shown to feature a spherically shaped Fourier transform of their
refractive-index distribution. We determine the direction and efficiency of
scattering from thin films made from such structures with the help of the Ewald
sphere construction which follows from first-order scattering approximation.
This way we present a simple geometrical argument why these structures are well
suited for creating short wavelength colors like blue but are hindered from
producing long wavelength colors like red. We also numerically synthesize a
model structure dedicated to produce a sharp spherical shell in reciprocal
space. The reflectivity of this structure as predicted by the first-order
approximation is compared to direct electromagnetic simulations. The results
indicate the Ewald sphere construction to constitute a simple geometrical tool
that can be used to describe and to explain important spectral and directional
features of the reflectivity. It is shown that total internal reflection in the
film in combination with directed scattering can be used to obtain long
wavelength structural colors.

11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci