Sun-Fi: Architecting Glass for Sunlight Data Transmission

Solar energy, as a sustainable power resource, has mainly been used for electricity generation and heating purposes. Nevertheless, large amounts of daylight are underutilized and primarily used for indoor lighting. In this article, we investigate exploiting sunlight as a green information carrier by passively modulating its power to stream data. Switchable glass technologies can be employed to manipulate the ambient light allowing optical wireless communications. In this context, we explore candidate smart-glass technologies and give an overview of the sunlight modulation communication system, called Sun-Fi. Then, based on the liquid crystal devices technology, we discuss the newly proposed architecture known as dual-cell liquid crystal shutters (DLS), which can establish a flicker-free communication link. Afterward, we stack the DLS elements in an array form while adopting polarization-based modulation and time division multiplexing to modulate the sunlight and transmit the required data. Finally, we define several open issues of the sunlight communication system and provide potential solutions.