What is Photonics?

Photonics: The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The range of applications of photonics extends from energy generation to detection to communications and information processing.

[from the trade magazine Photonics Spectra]

This term, which was coined in analogy with electronics, reflects the growing tie between optics and electronics forged by the increasing role that semiconductor materials and devices play in optical systems. Electronics involves the control of electric-charge flow (in vacuum or in matter); photonics involves the control of photons (in free space or in matter). The two disciplines clearly overlap since electrons often control the flow of photons and, conversely, photons control the flow of electrons. The term photonics also reflects the importance of the photon nature of light in describing the operation of many optical devices.

...photonics is used broadly to encompass... the generation of coherent light by lasers, and incoherent light by luminescence sources such as light-emitting diodes. the transmission of light in free space, through conventional optical components such as lenses, apertures, and imaging systems, and through waveguides such as optical fibers. the modulation, switching, and scanning of light by the use of electrically, acoustically, or optically controlled devices. the amplification and frequency conversion of light by the use of wave interactions in nonlinear materials. the detection of light.

[from Saleh & Teich, Fundamentals of Photonics]