Mirrors on a chip improve data transfer

Engineers at Ohio State University have created a device that promises to improve the speed of internet services.

Whether you’re waiting for a computer to download the latest movie trailer, or just holding for a long-distance phone call to connect, you may one day get faster service as the result of a new device invented by Ohio State University engineers.

The device, called an optical interconnect, transfers data from one fibre optic cable to another, using an array of microscopic mirrors on a silicon chip.

Today, data can’t switch between cables without passing through slow and cumbersome electronics – traditional wires that rely on electrons to carry information, not pulses of light, as optical fibres do.

‘Compared to optics, electrons are slower than death on crutches,’ said Betty Lise Anderson, associate professor of electrical engineering at Ohio State. ‘So the bottleneck at these connection points is fierce.’

The optical interconnect is covered with tiny mirrors that catches individual beams of light from fibre optic cable, and reflects them off to their destination, bypassing the traditional electronics that slow things down.

‘Imagine you wanted to send a message from Syracuse to Cincinnati,’ Collins said. ‘Right now, that message could travel by fibre optic cable, but it would have to pass through a series of electronic hubs in between. It would have to be converted from light into electrons, and back into light again. What we’d like to do is go directly from light to light, with the help of mirrors, prisms and lenses.’

While a handful of commercial companies have already developed their own such devices, Anderson and Collins expect Ohio State’s optical interconnect will be superior as their design is said to be more compact, versatile, and durable.

The new design involves a silicon computer chip covered with hundreds of thousands of tiny mirrors, each only a few tens of millionths of a meter across. The mirrors flip up and down to reflect the light signals along the desired route.

Other optical interconnects currently under development use a similar concept, Anderson said.

What makes Ohio State’s design different is that one of the mirrors is slightly askew. Beams of light that hit this offset mirror are bumped off in a slightly different direction.

By controlling how many times a beam of light bounces off the mirrors – and off the offset mirror in particular – researchers can guide a beam in virtually any direction.

The mirrors in other optical interconnects can only point light beams in one direction, Anderson said. ‘If one of those mirrors breaks, you can never make that connection again. With our scheme, if a mirror fails, we wouldn’t care, because other mirrors could take its place. We would have many different ways of getting the same output.’

The engineers said a working model of the optical interconnect could be years away, depending on the development of reliable techniques to fabricate the mirrors, and partnership with industry to commercialise the device.