To understand optics, we must understand light. A topic that alone would fill a large textbook, the physics of light forms the basis for understanding how optical fields propagate through materials and interfaces, leading to the effects on which optics is based. In this chapter we will review some of the basic physics required for understanding light propagation. The wave equation is derived from Maxwell's equations, and the types of wave solutions which satisfy it are discussed. We review energy and power flow, introduce polarization, characterize the wavefront, and finally discuss Gaussian beams. Numerous applications-oriented optics textbooks (Lipson et al., 1995; Smith and King, 2000; Iizuka, 2002a, 2002b; Brooker, 2003) discuss some of these topics in greater detail.

Basic electromagnetics

Our discussion here will focus on rudimentary electromagnetic field theory. Many readers will be familiar with some of the fundamentals of electromagnetics, and a wide selection of didactically excellent textbooks is available on the subject (Kraus and Carver, 1992; Jackson, 1998; Sadiku, 2001). Nonetheless, this first chapter provides an overview from which all students may benefit; even those readers for whom this is completely old hat may wish to peruse this section to familiarize themselves with the notation we employ in later sections.