Light absorbing silicon could realise optical computers

OPTICAL COMPUTERS have come one angstrom closer to reality after Yale University researchers found a way of making silicon semiconductors absorb 99 per cent of light.

To speed up computer performance, data transfer between processors using laser light has long been a goal of scientists. The ability of processors to receive and absorb that light means data transfer rates could potentially be improved dramatically.

And if silicon absorbing light isn't wacky enough the transmission and reception process uses two light sources. One is for the data and one is for tuning the absorption levels from 99 per cent, for example, down to 30 per cent.

This works, and read closely because here comes the science bit, because when the two light sources' waves combine inside the silicon they create a specific interference pattern that causes the energy to become trapped and converted to heat instead of being reflected back out.

Silicon normally only absorbs 60 per cent of light, so with an optical computer that could not be tuned you could lose 40 per cent of the data or waste energy retransmitting it to ensure the previous non-absorbed data was received.

The variable light absorption is also important for building an optical computer network because of the need for switching and routing. These functions can be carried out with the light absorbing optical semiconductors by increasing or decreasing or turning off the light absorption. µ