Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Design of a Power Amplifying-RIS for Free-Space Optical Communication
  Systems   The steering dynamics of re-configurable intelligent surfaces (RIS) have
hoisted them to the front row of technologies that can be exploited to solve
skip-zones in wireless communication systems. They can enable a programmable
wireless environment, turning it into a partially deterministic space that
plays an active role in determining how wireless signals propagate. However,
RIS-based communication systems' practical implementation may face challenges
such as noise generated by the RIS structure. Besides, the transmitted signal
may face a double-fading effect over the two portions of the channel. This
article tackles this double-fading problem in near-terrestrial free-space
optical (nT-FSO) communication systems using a RIS module based upon
liquid-crystal (LC) on silicon (LCoS). A doped LC layer can directly amplify a
light when placed in an external field. Leveraging on this capacity of a doped
LC, we mitigate the double-attenuation faced by the transmitted signal. We
first revisit the nT-FSO power loss scenario, then discuss the direct-light
amplification, and consider the system performance. Results show that at 51
degrees of the incoming light incidence angle, the proposed LCoS design has
minimal RIS depth, implying less LC's material. The performance results show
that the number of bit per unit bandwidth is upper-bounded and grows with the
ratio of the sub-links distances. Finally, we present and discuss open issues
to enable new research opportunities towards the use of RIS and amplifying-RIS
in nT-FSO systems.

30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th