Design and Analysis of LCD-Based Modulator for Passive Sunlight Communications

Solar energy is widely used for electricity generation, heating systems, and indoor environment daytime illumination. Indeed, large amounts of sunlight energy remain insufficiently used. In this work, we aim at employing sunlight energy for data transmission as a green option for wireless communications. Being emitted by an uncontrollable source, taming the sunlight is a challenging task that requires appropriate technologies to manipulate incident light. Liquid crystal devices are switchable glass technologies that have adequate response time and contrast characteristics for such an application. In this regard, we design a novel dual-cell liquid crystal shutter (DLS) by stacking two liquid crystal cells that operate in opposite manners, and we build our sunlight modulator with an array of DLSs. Then, we adopt time division multiplexing and polarization-based modulation to boost the data rate and eliminate the flickering effect. In addition, we provide mathematical modeling of the system and study its performance in terms of communication and energy consumption. Finally, we introduce some numerical results to examine the impact of multiple parameters on the system's performance and compare it with the state-of-the-art, which showed that our system features higher data rates and extended link ranges.