optics

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agrav8r

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Since there are a number of people interested in optics i thought i would post this.
In the fozen light thread spiderwebs being covered in filiment was mentioned and this seems similar.


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Naked nanofibres stretch optical properties


10:42 18 December 03



A new type of nanoscale optical fibre is showing promise in applications such as light-based computing and chemical sensing.

Optical fibres transmit light through an inner core surrounded by cladding. But the new fibres have an ultra-thin silica core, with the atmosphere acting as the cladding. These fibres are so fine that they are thinner than the wavelengths of light they carry.

The core material must be very smooth to create a consistent boundary between silica and the atmosphere, as rough edges scatter a light wave. To ensure a regular surface, Eric Mazur of Harvard University stretched glass through a sapphire cone heated to melt the silica without exposing it to flame turbulence.

"We're close to the atomic level in smoothness," he says. He has made fibres as thin as 50 nanometres, more than 2000 times as fine as standard fibres.


Ideal connectors





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Eric Mazur, Harvard University

The Fiber Optic Association

Nature




The thinner the fibre, the greater the portion of the wave that travels along its surface. For instance, the fraction of light guided outside the silica increases from 50 per cent for a 300-nanometre fibre to 90 per cent for a 50-nanometre fibre.

This characteristic could make them ideal connectors in the photonic circuits of future light-based computers.

The minuscule fibres are also extremely sensitive to chemicals. So engineers could place certain chemical receptors on the fibre's surface. When these bind to an agent, the receptors would change shape, altering the fibre's optical properties in a way that identifies the chemical.

Journal reference: Nature (vol 426, p 816)


Jeff Hecht
 
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