Rami Arieli: "The Laser Adventure" Chapter 9.4.4 page 1

9.4.4 optical computer - processing information at the speed of light!
Electronic computers are limited by the speed of current flow through the wires inside the computer.
By using pulses of light instead of electrical currents it is possible to increase by orders of magnitude the speed of the computers.In electronics, it is possible today to put millions of transistors into one integrated circuit (IC).
For optical computers, similar circuits are needed to be developed, and they are called integrated optics (IO). This is a new research subject and there are not yet commercial products of optical computers. In the laboratory, scientists have demonstrated simple operations of edition and multiplication, but it will probably take more than 10-20 years until such products will be available.

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