1. The biological applications of photonics, a technology that utilizes light and other forms of radiant energy in which a quantum unit is the photon (the smallest unit used to measure a physical property).
2. A combination of biology and photonics, with photonics being the science and technology of generation, manipulation, and detection of photons, quantum units of light.

Photonics is related to electronics in that it is believed that photons will play a similar central role in future information technology as electrons do today.

It includes the study or application of electromagnetic energy whose basic unit is the photon, incorporating optics, laser technology, electrical engineering, materials science, and information storage and processing.