A team from the university’s physical and theoretical chemistry research group has developed a simple way to direct light in and out of the side of fibre-optic cables that doesn’t require relatively expensive splitting or coupling devices.
Originally developed to improve a spectrographic method of analysing liquids, the technique could be useful to the telecoms industry as a way of taking a small amount of light out of a cable to check the signal.
‘This just provides a fairly simple means of doing that,’ lead researcher Dr Claire Vallance told The Engineer. ‘The nice thing about it is it will work for any wavelength of light.
‘Most existing fibre beam splitters or couplers… are optimised for a particular wavelength of light. Whereas our one, because it’s based on a kind of micro-mirror, will work at any wavelength.’
The method involves cutting an optical cable in half and cutting a 45° notch in the corner of one of the exposed ends. Using a straightforward chemical process, the scientists were able to deposit aluminium on this corner to create a mirror.
Reattaching the two cable ends created an entrance and exit point in the optical fibre for light to be directed in or out.
‘We ended up having to do some kind of clever coupling chemistry that chemically bonds the aluminium just to the notched bit and not the other bit,’ said Vallance. ‘Once we figured that out it worked straight away.’
Oxford University’s technology-transfer firm, Isis Innovation, is now looking to license the technique to interested companies.
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