The practical uses of the words photonics, electro optics and optoelectronics often differ from some of their stated definitions. When looking for a product, job, or literature related to optics and electronics, listings can appear in what seems an inappropriate place.

It may be useful in practical situations to ignore the strict distinctions as defined below, and apply all three terms to obtain more information than would result from strictly following some stated definitions.


Photonics Dictionary defines photonics as “the technology for generating and harnessing light…whose quantum unit is the photon…” Its definition includes the means for producing, controlling, sensing/detecting light by optical components and instruments. It does include electro-optical instrumentation. Photonics is the broadest of the three terms.

Electro-optics is defined as the “use of applied electrical fields to generate and control optical radiation. However, it would appear from this definition, and from others, that it would apply to material changes due to electric fields such as occur with liquid crystal displays, such as Kerr & Pockels effects. A warning is provided that “electro-optic (E-O) is often used erroneously as a synonym for optoelectronic.”

Finally, optoelectronics is said to pertain “to a device that responds to optical power, emits or modifies optical radiation or utilizes optical radiation for its internal operation” or “any device that functions as an electrical-to-optical or optical-to electrical transducer.”


For example, a New Hampshire-based defense systems company was seeking an electro-optical systems engineer. It noted that the technical responsibilities for the role are “for the development of high-performance, high-precision, military infrared imaging/sensor systems, multispectral imaging/sensor systems, and hyperspectral imaging/sensor systems.” Not quite the same as the aspects mentioned above.

When you go to ThomasNet, the companies listed have somewhat different definitions.

For example, Banner Engineering states that it is “a manufacturer of electro-optical equipment and systems used in industrial process automation and control applications. Products include photoelectric sensors, opto-electric (sic) sensors….”.

Sick Ltd. states that it is a “manufacturer and designer of optoelectronic and electro-optical equipment, systems and devices including single-beam photoelectric safety switches…” The company’s products do not appear to mention electro-optical products as defined above.


Our intention here is to suggest, for comprehensiveness, the use of all three of these words-photonics, electro optics, and optoelectronics-to any relevant computer searches for products, jobs, literature and more.