  Reconfigurable intelligent surfaces (RIS) have been recently introduced to
optical wireless communication (OWC) networks to resolve skip areas and improve
the signal-to-noise ratio at the user's end. In OWC networks, RIS are based on
mirrors or metasurfaces. Metasurfaces have evolved significantly over the last
few years. As a result, coding, digital, programmable, and information
metamaterials have been developed. The advantage of these materials is that
they can enable digital signal processing (DSP) techniques. For the first time,
this paper proposes the use of digital RIS (DRIS) in OWC systems. We discuss
the concept of DRIS and the application of DSP methods to the physical
material. In addition, we examine metamaterials for optical DRIS with liquid
crystals serving as the front row material. Finally, we present a design
example and discuss future research directions.
