Integrated optics seeks to emulate the architecture and varied functionality of integrated electronics on an optical platform. As such, this eld encompasses research on all individual optical devices and optical circuits that can be fabricated monolithically on a single chip to carry out complex optical processing functions. e terms “integrated optics” and “waveguide optics” o en seem interchangeable, since most integrated optical chips use optical waveguides as the basic building block for both devices and as the optical paths linking di erent devices on the chip. Many commercially successful devices such as charge-coupled device (CCD) arrays and vertical cavity surface emitting laser (VCSEL) arrays do not use waveguides, yet are obviously highly integrated multicomponent optical devices. Nevertheless, the purpose of this chapter is to provide a brief overview of only waveguide-based integrated optics. Passive waveguide devices a re t hose t hat require no e xternal power or control sig nals. A n i ntegrated opt ical chip may contain passive waveguide-based optical splitters and combiners, interferometers, spectrometers, as well as active devices such as modulators, photodetectors, and lasers.