Optical wireless communication (OWC) has received considerable attention for a variety of applications due to the broad unlicensed spectrum. OWC systems operate over different frequency bands to carry information on optical signals, which are then ultraviolet, visible, and infrared. In this tutorial, we will mainly focus on infrared OWC, commonly referred to as free space optics (FSO).
FSO can guarantee a high-bit-rate line of sight transmission over long distances of up to several kilometers. As such, FSO is an attractive solution to the last-meter and last-mile connectivity problems in communication networks, mainly when fiber optics installation is unavailable. Installing FSO systems can significantly help to tackle the ``digital divide’’ by lowering the installation time and cost. FSO is equally expected to be a significant part of the beyond 5G eras.
Throughout the tutorial, we will equally discuss from the experimentalist’s point of view the primary channel and hardware challenges for FSO systems, including those employing structured light beams. We will also present the possible mitigation strategies of propagation effects and discuss their practicality. We will further give insights into our experimental work on how to potentially use structured light beams beyond laboratory test benches to establish real-world outdoor FSO communications.
Other FSO applications, including satellite-to-satellite and ground–to satellite communication, will be discussed. Finally, we will identify open problems and provide future research directions.