Integrated Optics

In the case of an electronic integrated circuit (IC), e.g., for a shift register IC, one normally does not worry about how each flip-flop unit is functioning. The only concern is whether or not the input and output electrical signals are correct. The IC’s are packaged in small black plastic cases, and they are literally looked upon as black boxes.

A similar objective has been the goal of integrated optics. When this goal is reached, no one will have to worry about vibration, coupling between components, temperature, dust, or moisture. Various optomodules could then presumably be integrated on a small substrate the size of a microscope deck glass for easy handling. The optomodules would contain thin-film devices such as modulators, directional couplers, switches, bistable optical devices, lenses, A/D converters and the spectrum analyzer. This chapter begins with a fundamental waveguide analysis and an introduction to coupled mode theory. Following this analysis is a description of the basic thin film devices which form the building blocks of integrated optics. A summary of the thin-film techniques that were specifically developed in connection with integrated optics is also included.

Before proceeding, a word of caution is advised concerning categorization. Quite often, a single integrated-optics device may provide a variety of functions. For example, the same basic integrated optics component may be used as a modulator, a switch, or a directional coupler. Therefore, to use the phrase “directional coupler” as the name of a subsection may be misleading. Despite this drawback, every attempt has been made to present the material in an order which is easy to comprehend.