Towards the use of re-configurable intelligent surfaces in VLC systems : beam steering

Ndjiongue, Alain R. and Ngatched, Telex M. N. and Dobre, Octavia A. and Haas, Harald (2021) Towards the use of re-configurable intelligent surfaces in VLC systems : beam steering. IEEE Wireless Communications, 28 (3). pp. 156-162. ISSN 1536-1284 (

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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 article, we exploit these RIS attributes to steer the incident light beam, offer the VLC receiver a large range of rotation angle, and improve its field-of-view. We show that instead of using convex, parabolic, or spherical lenses, adopting a meta-lens with artificial muscles or a thin-film Liquid-Crystal with embedded Titanium dioxide nano-disk, a VLC receiver can detect light rays at a high incidence angle with high precision and considerable improvement in the detected light intensity, even with a miniaturized single photodetector.