Towards the Use of Re-configurable Intelligent Surfaces in VLC Systems: Beam Steering

Abstract

The emergence of visible light communication (VLC) technology as a solution to solve radio frequency impediments, such as spectrum shortage, is continuously appealing. In addition to its large and unlicensed bandwidth, VLC provides a high level of security in a closed room with zero radio frequency interference. However, loss of the VLC signal is experienced when the receiver rotates or moves. This challenge requires a special solution for integration into portable devices. On the other hand, re-configurable intelligent surface (RIS) is a technology exploited in radio frequency to solve dead zones and loss of signal. RIS elements are characterized by tunable physico-chemical characteristics including physical depth and refractive index. In this paper, we exploit these RIS attributes to steer the incident light beam and offer the VLC receiver a large range of rotation angle while improving its signal detection capabilities. We show that instead of using convex, parabolic, or spherical lenses, adopting a meta-lens with artificial muscles or a thin-film crystal-liquid with embedded Titanium dioxide nano-disk, a VLC receiver can detect light rays at $90^o$ incidence angle with high precision and considerable improvement in the detected light intensity, even with a miniaturized single photodetector.