Optical Computer Circuit Made From Lasers, Glass

Researchers have combined laser beams and specially coated glass to produce the first computer-type circuit that processes data with light rather than electronically, scientists say.

The simple circuit is an important step in showing the feasibility of “optical computing,” said Frank Tooley, a lecturer in the physics department of Heriot-Watt University in Edinburgh, Scotland.

Tooley is co-author of a report on the circuit in today’s issue of the British journal Nature.

In an accompanying editorial, Alan Miller of the Royal Signals and Radar Establishment in Malvern, England, wrote that the research demonstrates that optical devices can fulfill several key requirements for setting up computer circuits.

Future Computer Design

It also shows that optics could be useful in so-called parallel computing, Miller wrote. In that concept, computers carry out many operations at once. Standard computers perform one operation at a time.

Scientists are interested in optical computing as they look to future computer design. One problem with standard computer electronics is that when wires are jammed close together, their electric currents can interfere with each other. But light beams can pass through each other without interference, allowing easier interconnections in tight quarters.

Light beams also carry information faster than wires can.

But scientists do not know how optical computers would compare to future electronic machines in speed, size, cost, reliability or other considerations, said R. A. Athale, manager of the optical computing technology group at BDM Corp., a McLean, Va., consulting, research and development concern.

May Have Different Role

Some hope that optical machines will handle entirely different classes of problems than today’s computers do, he said.

Besides the Heriot-Watt group, key optical computing research is being done by scientists at AT&T; Bell Laboratories in Holmdel, N.J., and the University of Arizona.

The Heriot-Watt circuit consists essentially of three specially coated glass plates, each of which functions like a switch that can turn the next “switch” in the circuit on or off. The plates, along with lenses and mirrors, are positioned so that laser beams can be passed from one plate to the next around a loop, eliminating the need for wires.

The switching ability lies in the coating on the glass. The coating can either reflect the laser beam or let it pass through, depending on whether the “switch” is on or off.