Photonics in Different Fields

Relationship to other fields
Classical optics
Photonics is closely related to optics. However optics preceded the discovery that light is quantized (when the photoelectric effect was explained by Albert Einstein in 1905). The tools of optics are the refracting lens, the reflecting mirror, and various optical components which were known prior to 1900. The key tenets of classical optics, such as Huygens Principle, the Maxwell Equations, and wave equations, do not depend on quantum properties of light.
Modern optics
Photonics is approximately synonymous with quantum optics, quantum electronics, electro-optics, and optoelectronics. However each is used with slightly different connotations by scientific and government communities and in the marketplace. Quantum optics often connotes fundamental research, whereas photonics is used to connote applied research and development.
The term photonics more specifically connotes:
1. the particle properties of light,
2. the potential of creating signal processing device technologies using photons,
3. those quantum optical technologies which are manufacturable and can be low-cost, and
4. an analogy to electronics.
The term optoelectronics eponymously connotes devices or circuits comprising both electrical and optical functions, i.e., a thin-film semiconductor device. The term electro-optics came into earlier use and specifically encompasses nonlinear electrical-optical interactions applied, e.g, as bulk crystal modulators such as the Pockels cell, but also includes advanced imaging sensors typically used for surveillance by civilian or government organizations.
Emerging fields
Photonics also relates to the emerging science of quantum information in those cases where it employs photonic methods. Other emerging fields include opto-atomics in which devices integrate both photonic and atomic devices for applications such as precision timekeeping, navigation, and metrology. Another emerging field is polaritonics which differs with photonics in that the fundamental information carrier is a phonon-polariton, which is a mixture of photons and phonons, and operates in the range of frequencies from 300 gigahertz to approximately 10 terahertz.

Overview of photonics research
The science of photonics includes the emission, transmission, amplification, detection, modulation, and switching of light.
Photonic devices include optoelectronic devices such as lasers and photodetectors, as well as optical fiber, photonic crystals, planar waveguides, and other passive optical elements.
Applications of photonics include light detection, telecommunications, information processing, illumination, metrology, spectroscopy, holography, medicine (surgery, vision correction, endoscopy, health monitoring), military technology, laser material processing, visual art, biophotonics, agriculture and robotics