Overview

The benefits of the marriage between optics and electronics are readily apparent in television cameras, camcorders, digital cameras, and night-vision telescopes, to mention but a few common examples. But optoelectronics can be considered as having two realms: the visible and the nonvisible. Operating in the visible realm are devices, circuits, and systems whose outputs are signals, indications, text, or images that can be seen by the human eye. These include displays that either emit visible light or are intended to be seen in visible light. By contrast, devices, circuits, and systems that emit nonvisible infrared (IR) and ultraviolet (UV) energy, or those whose functions depend on that energy, are considered to be in the nonvisible realm. This section focuses primarily on the nonvisible realm.

The development of simple, reliable, low-cost semiconductor IR-emitting diodes and lasers with matched photodetectors has made possible such devices as optocouplers and such products as digital remote controls, laser printers, scanners, code readers, and CD (compact disk) players. It has also made long- and short-haul optoelectronic communication practical.

Fiberoptic cables are now competing with wire and coaxial cables as conductors of telephone conversations, television programming, computer data, and still pictures. These cables can transmit information in the form of modulated light over long distances without additional amplification. Complete families of IR photoemitters and photodetectors have evolved, making it easy to convert IR energy back and forth to electrical signals.

Night-vision tubes permit scenes to be viewed at night that are illuminated only by...