Sapphire based chip trades copper wires for light

A team at Johns Hopkins University in the US has developed a prototype chip that uses light instead of wires as an interface.

Professor Andreas Andreou, laboratory director, said: "We have developed a very fast and cost-effective way of getting data on and off a chip without using wire. It really promises to revolutionise how computer systems for homes and businesses are put together."

By adding a layer of synthetic sapphire to a semiconductor wafer and bonding microdetecters on to the sapphire, light transmissions are made possible. An optical receiver is attached to the sapphire layer and converts the light signal back into an electrical one compatible with the chip's electrical circuits.

The signal is transformed into light and beamed through the sapphire substrate via a tiny laser. Microlenses and other optical components, manufactured on the chip, collect the light beam and guide on the chip or, using an optical fibre, move it to another chip.

At its destination, the light enters a high-speed optical receiver circuit that converts the stream of photons into a stream of electrons suitable for interfacing with other computer components.

By using optical signals, the researchers believe a signal could move 100 times faster than it does along a metal wire. The optoelectric interface circuits require much less power because the sapphire substrate is an insulating material, not a semiconductor.

This interface could significantly improve the internal transfer rate among chips in computers. The prototype can shunt information on and off the chip at 1 Gbps. The current components of the prototype are 0.5 µm wide, but the researchers believe that the next generation will have features as small as 0.1 µm. At that size, the design has the potential to run at 5 Gbps.