Liquid crystal optical shutter as a low power active surface for visible light communication

Visible Light Communication (VLC) has gained significant interest for vehicle-to-everything (V2X) applications due to its high data rates and unlicensed spectrum. However, the energy consumption of VLC transceivers remains a critical challenge, especially for resource-constrained devices like sensors and Internet of Things (IoT) nodes. In this work, we propose a novel energy-efficient VLC system that leverages passive reflecting devices to enable low-power communication. We implement two use cases: 1) Vehicle headlights as transmitters and photovoltaic modules as receivers/energy harvesters, and 2) Retroreflectors modulated by liquid crystal displays (LCDs) for the reverse link. The key innovation is the use of retroreflectors, which reflect incident light back towards the source with minimal power consumption. By modulating these retroreflectors with LCDs, we enable low-energy uplink communication from sensors to vehicles without active transmitters. We develop customized hardware and software for the sensing platforms and VLC infrastructure. Extensive simulations and experimental evaluations demonstrate significant energy savings compared to traditional VLC systems.