Spectral Characterization of an LC-Based Optical Shutter as Modulator for Secure VLC-based Wireless Sensing in V2X Scenarios

This paper presents a novel Visible Light Communication (VLC) system especially designed for secure, low-power Vehicle-To-Everything (V2X) wireless sensing applications. The system includes a Liquid Crystal (LC)-based optical shutter with a retroreflector to enable bidirectional communication solely resorting to passive-transmitters. A square-wave signal drives the optical shutter to modulate a high-frequency light signal from a cool-white LED that will be then possibly processed into a received signal by a Reduced Instruction Set Computer(RISC)-V architecture. Thorough experimental characterization proved voltage-dependent variation in transmittance, reflectance, and absorptance across ultraviolet, visible, and infrared spectral ranges, thus confirming the actual feasibility of the proposed modulation technique. Preliminary results support the implementation of such a system for wireless sensing applications in smart transportation and Internet of Things (IoT) contexts, with future works directed at the full system integration.