SOMETIMES a new material can revive the fortunes of a technology that has yet
to fulfil its promise. Microchips, for instance, became much cheaper and easier
to manufacture when makers switched to using silicon rather than germanium. A
group of Australians is hoping to pull off a similar feat with advanced optical
fibres鈥攖he sort with holes running all the way through them. They say
simply switching from glass to plastic fibre will make the technology more
viable.
Holey optical fibres were invented by Philip Russell and his team at the
University of Bath. The idea was to boost the performance of glass optical
fibres by running an array of tiny holes all along their length
(快猫短视频, 18 July 1998, p 20).
Depending on the shape of the pattern of
holes, the fibres acquire new abilities. They can simultaneously transmit
separate data streams at different light wavelengths, or carry a high-power
central beam using a broad central gap (see Graphic).
But holey glass fibres are difficult to make鈥攁nd therefore expensive.
You have to stack silica tubes in a bundle and heat them to melting point, then
stretch the fibre to the desired length. But it鈥檚 hard to keep the hot holes
from slumping and closing up. Although companies are attempting to commercialise
the idea, little of the holey fibre has made it to market.
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Now, an Australian company called Redfern Polymer Optics and the Australian
Photonics Cooperative Research Centre in Sydney reckon plastic fibre is the
answer. Ian Maxwell of Redfern told a conference in Amsterdam last week that the
trick is to use a single hunk of cheap polymer and mould it or extrude it
through a former that gives the fibre the correct hole profile. Then they can
make use of the fact that with polymer chains arranged lengthwise, the
troublesome holes do not collapse. The holey plastic fibres can do virtually
everything the glass ones can鈥攂ut for a fraction of the cost.
Even the inventor of holey fibres is impressed. 鈥淪omebody needed to do this,鈥�
says Russell. 鈥淚t may well lead to some interesting new industries.鈥�