ABSTRACT
This chapter is an introduction to the near-Earth laser communication technology. By near-Earth, we mean high-altitude platforms and Earth-orbiting satellites. Justification for high bandwidth delivery capability as well as key advantages and challenges of laser communications are discussed in detail. Critical elements of each subassembly are introduced and elaborated separately for the flight and the ground subsystems. These include the atmospheric effects, laser transmitter, receiver, optomechanical assembly, laser beam acquisition tracking and pointing, modulation and coding. Past successful optical communications links and upcoming field demonstrations and major operational use cases are also summarized here. Each of the following chapters expands on these topics in much greater detail.
