  Visible light communication (VLC) enables access to huge unlicensed
bandwidth, a higher security level, and no radio frequency interference. With
these advantages, VLC emerges as a complementary solution to radio frequency
communications. VLC systems have primarily been designed for indoor scenarios
with typical transmission distances between 2 and 5 m. Different designs would
be required for larger distances. This paper proposes for the first time the
use of a liquid crystal (LC)-based re-configurable intelligent surface (RIS) on
improving the VLC signal detection and transmission range. An LC-based RIS
presents multiple advantages, including the tunability of its photo-refractive
parameters. Another advantage is its light amplification capabilities when
under the influence of an externally applied field. In this paper, we analyze
an LC-based RIS structure to amplify the detected light and improve the VLC
signal detection and transmission range. Results show that mixing LC with 4 to
8 wt\% concentration of a dye such as the terthiophene (3T-2MB) improves the
VLC transmission range of about 0.20 to 1.08 m. This improvement can reach 6.56
m if we combine 8 wt\% concentration of 3T-2MB and 0.1 wt\% concentration of
trinitrofluorenone.
