Really 'light' computers

We've been told for a while that our computers will one day use light instead of electricity. But if transistors control the flow of electricity with on-off switches, it is trickier to control photons to simulate ones and zeros.

We've been told for a while that our computers will one day use light instead of electricity. But if transistors control the flow of electricity with on-off switches, it is trickier to control photons to simulate ones and zeros. Now, researchers at the University of Alberta are using a process called Glancing Angle Deposition (GLAD) to build photonic crystals and to develop future 'all-optical' computers. There are still several major issues to handle before we can use these speedy computers, but read more...

This GLAD process has been developed by the GLAD Research Group led by Professors Michael Brett and Jeremy Sit. It "uses a beam of high-energy electrons to transfer silicon atoms to a flat surface at an oblique angle, forming a highly ordered structure." Here is how this technique works according to this overview of thin films and GLAD.

The oblique (glancing) angle regime includes angles greater than 80°, measured between the substrate normal and the direction of incident vapour (this angle is denoted by alpha, α) At such large angles, any atoms already deposited on the substrate create atomic shadows behind them, shielding that area from the other incident atoms." (Credit: GLAD research group)
How GLAD deposits thin films
"By restricting where incident atoms can bond to the substrate, the shadowing effect ensures that incident atoms will join with nuclei already formed on the surface. [...] Under glancing angle conditions, these nuclei will continue to grow in a slanted fashion; eventually, a series of slanted columns will emerge. This is the first indication of film microstructure control through GLAD." (Credit: GLAD research group)
Film microstructure control through GLAD

Now, it's time to read the University of Alberta article, which is centered about Mark Summers, an electrical and computer engineering graduate student. Here is what he says about photons.

"The photon can be thought of as an ideal information carrier, superior to the electron in terms of transmitting data." Summers said. "In optics, you overcome the problems associated with heat dissipation, and you can fit a lot more information at particular wavelengths in the same amount of space."

Please take some time to read the article for more information about the GLAD technique. But will it lead to optical computers? Summers thinks it's possible, but it will be realized in three separate stages.

"The first stage will involve integrating optical interconnects between the various chips inside a computer increasing the bandwidth between the devices. The next stage is to integrate microelectronic circuits with microphotonic circuits, and the final stage will be everything optical, all the way to the human interface," he explained.

Finally, here is a link to many pictures of various examples of GLAD thin films which have already been made at the GLAD lab -- and which will have practical applications many years before an all-optical computer appears on the market.

Sources: Sean McClure, The Gateway, University of Alberta, October 12, 2006; and various websites

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