Definition Series: Optical Computing

Today I come back to the this Blog’s definition series. And the definition I’ve chosen to post here is one close to a background I used to know in a specialized way: optoelectronics was the subject matter I graduated from. In spite of that graduation happened in the far away 2003 year, I still quite remember the topic with care and interest.

This definition was written in March 2011 in the computer glossary website. But given the recent rejuvenating interest in Optical Computing, I still see that it’s quite actual regarding the main points of the subject. The quest to one day the photonic network of all electro-optic components be a reality isn’t abated completely, but the need for bolder scalable innovations that mitigate risks and costs might still persist for unknown time. In the end the full adoption and success of Optical Computing will bet a matter of the right combination of factors with some luck mixed in:

optical computer (photonic computer)


An optical computer (also called a photonic computer) is a device that uses the photons in visible light or infrared ( IR ) beams,rather than electric current, to perform digital computations. An electric current flows at only about 10 percent of the speed of light. This limits the rate at which data can be exchanged over long distances, and is one of the factors that led to the evolution of optical fiber . 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 10 or more times faster than a conventional electronic computer.


Visible-light and IR beams, unlike electric currents, pass through each other without interacting. Several (or many) laser beams can be shone so their paths intersect, but there is no interference among the beams, even when they are confined essentially to two dimensions. Electric currents must be guided around each other, and this makes three-dimensional wiring necessary. Thus, an optical computer, besides being much faster than an electronic one, might also be smaller.


Some engineers think optical computing will someday be common, but most agree that transitions will occur in specialized areas one at a time. Some optical integrated circuits have been designed and manufactured. (At least one complete, although rather large, computer has been built using optical circuits.) Three-dimensional, full-motion video can be transmitted along a bundle of fibers by breaking the image into voxels. Some optical devices can be controlled by electronic currents, even though the impulses carrying the data are visible light or IR.


Optical technology has made its most significant inroads in digital communications, where fiber optic data transmission has become commonplace. The ultimate goal is the so-called photonic network , which uses visible and IR energy exclusively between each source and destination. Optical technology is employed in CD-ROM drives and their relatives, laser printers, and most photocopiers and scanners. However, none of these devices are fully optical; all rely to some extent on conventional electronic circuits and components.



I further add to this definition the addition of a more current view from the Wikipedia page of the subject where the main challenges are identified:



A significant challenge to optical computing is that computation is a nonlinear process in which multiple signals must interact. Light, which is an electromagnetic wave, can only interact with another electromagnetic wave in the presence of electrons in a material,[8] and the strength of this interaction is much weaker for electromagnetic waves, such as light, than for the electronic signals in a conventional computer. This may result in the processing elements for an optical computer requiring more power and larger dimensions than those for a conventional electronic computer using transistors.




There are disagreements between researchers about the future capabilities of optical computers: will they be able to compete with semiconductor-based electronic computers on speed, power consumption, cost, and size. Critics note that[7] real-world logic systems require “logic-level restoration, cascadability, fan-out and input–output isolation”, all of which are currently provided by electronic transistors at low-cost, low power, and high-speed. For optical logic to be competitive beyond a few niche applications, major breakthroughs in non-linear optical device technology would be required, or perhaps a change in the nature of computing itself.



Fascinating subject still close to my mind and heart.


Featured Image: Optical Computing

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