An optical computer (also called a photonic computer) is a device that performs its computation using photons of visible light or infrared (IR) beams, rather than electrons in an electric current. The computers we use today use transistors and semiconductors to control electricity but computers of the future may utilize crystals and metamaterials to control light.
An electric current creates heat in computer systems and as the processing speed increases, so does the amount of electricity required; this extra heat is extremely damaging to the hardware. Photons, however, create substantially less amounts of heat than electrons, on a given size scale, thus the development of more powerful processing systems becomes possible. By applying some of the advantages of visible and/or IR networks at the device and component scale, a computer might someday be developed that can perform operations significantly faster than a conventional electronic computer.
Electro-Optical Hybrid computers
Pure Optical Computers
All-optical computers eliminate the need for switching. These computers will use multiple frequencies to send information throughout computer as light waves and packets thus not having any electron based systems and needing no conversation from electrical to optical, greatly increasing the speed.