Later On

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Jewels from technology

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When will they come to market?

Diamonds are so last year. Gems of rare beauty can now be made from simple chunks of silicon using technology developed for telecommunications.

The artificial gems are examples of a photonic crystal – nanoscale repeating structures that reflect different wavelengths of light at different viewing angles. Which wavelengths are reflected and in which direction depends on the repeating pattern.

This property is exploited in telecommunications to separate signals carried by different wavelengths within the same optical fibre. It also makes the crystals appear to change colour as the viewer’s perspective changes.

It was this flickering light from opal, a naturally occurring photonic crystal, that inspired Tom Mossberg of Lightsmyth Technologies in Eugene, Oregon, to use photonic crystals to make gems.

To produce the gems, Mossberg used photolithography to carve circular, hexagonal and triangular spaces between 3 and 20 millimetres wide into a silicon wafer. In optical fibres, a crystal with just one pattern does the job, but he etched some 200 different patterns into each gem. Each pattern reflects light of a different wavelength in a different direction, which produces gems that flash a variety of colours in all directions. “It’s a bit surprising that a high-tech photonic concept might end up making a beautiful thing,” he says.

Cut diamonds have a similar effect, but photonic crystal gems could be mass produced inexpensively. Mossberg hopes to use quartz or sapphire in place of expensive silicon wafers.

Written by Leisureguy

24 November 2007 at 2:44 pm

Posted in Daily life, Technology

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