Photonics is the science and technology of generating and controlling photons, particularly in the visible and near infra-red spectrum. Photonics as a science is closely related to quantum optics and optoelectronics with somewhat unclear boundaries. Quantum optics frequently implies fundamental research, while photonics often refers to more application-related research.
Many different fields use photonics regularly. Photonics is used by medical professionals to correct poor eyesight and to do laser surgery. The military uses it to detect mines. Construction companies do laser leveling and rangefinding by photonics. Even the entertainment industry finds uses for photonics in light shows and holographs.