Editing Photonics (section)

===Classical optics===
Photonics is closely related to [[optics]]. Classical optics long preceded the discovery that light is quantized, when [[Albert Einstein]] famously explained the [[photoelectric effect]] in 1905. Optics tools include the refracting [[lens]], the reflecting [[mirror]], and various optical components and instruments developed throughout the 15th to 19th centuries. Key tenets of classical optics, such as [[Huygens Principle]], developed in the 17th century, [[Maxwell's Equations]] and the wave equations, developed in the 19th, do not depend on quantum properties of light.