Introduction

This introduction presents an overview of key concepts discussed in this book. The book covers different types of applications where both light‐emitting‐diodes (LEDs) and lasers are used. Optical wireless communications (OWC) has become an increasingly important research area. The existence of millions of remote controls that operate using infrared LEDs is a proof of the usefulness of optical wireless systems. Apart from the various applications of OWC that are currently in use, the main motivating factor to focus on this area is the possibility of mitigating the increasing spectrum shortage issue. OWC can be both indoors and outdoors and are divided into two categories based on the type of optical source employed. Two types of optical sources, LEDs and lasers, are currently in use as transmitters of optical links. LED‐based communications involve visible light communications (VLC) using white LEDs (WLEDs), and lasers are used only as very high‐speed infrared sources.