# What is "Photonics"? **Photonics vs. Optics** Optics and photonics are often used interchangeably, although their meaning can vary depending on the context. In fact, an ongoing debate among experts has yet to find a conclusion on what the exact differences are \[1\]. Here is our take on it: "optics" often refers to the classical concept of light rays, the study of vision, and the transmission, reflection, and absorption of light in different media \[2\]. In contrast, "photonics" emphasizes the quantum mechanic dual character of light, in particular the "quanta" of light (the photons!) \[3\]; moreover, it also often refers to the technologies and the industry that involve optics and optical instruments \[2\]. This, of course, is only a brief summary of online sources, and one could discuss in length more details. If you want to share your thoughts, [send us an email](mailto:photonics@seas.harvard.edu)! References: \[1\] Optics.org: Optics or photonics: what’s in a name? accessed: 2011-08-30. \[2\] New Oxford American Dictionary, accessed: 2011-08-30. \[3\] Wikipedia: Photonics accessed: 2011-08-30.