Capturing the light (Image: iStockphoto)
An antenna that captures visible light like radio antennas capture radiowaves has been invented by U.S. researchers.
They said the device, which uses tiny carbon nanotubes, may one day lead to optical television or a way of converting solar energy into electricity.
The researchers will publish their work in the 27 September issue of the journal Applied Physics Letters.
Radio and television signals are captured using antennas close to the size of the wavelength of broadcast radiation. These wavelengths are often huge, hence the need for tall antennas.
In a receiver, the wave excites electrons into meaningful currents, which are amplified and tuned to carry sound and pictures.
But capturing light rather than radiowaves is a different matter. As wavelengths of visible light are in the nanometer range, an antenna to capture light would have to be on a similar scale.
In nature, cells in the eye capture visible light and translate them into electrical signals.
But the researchers replicated this in the lab using nanomaterials.
Yang Wang and colleagues at Boston College used carbon nanotubes, microscopic structures built of carbon atoms.
The tubes were about 50 nanometers wide, hundreds of nanometers long and aligned randomly.
Light excited the nanotubes to produce miniature electrical currents.
A visible-light antenna might work by receiving a television signal superimposed onto a laser beam sent down an optical fibre, the researchers said.
S:http://www.abc.net.au/science/articles/2004/09/20/1202875.htm
This technology may improve the efficiency and quality of television signals, they said.
Or they said it could be used as the basis of an efficient solar energy device that turns incoming light into an electrical charge to be stored in a capacitor.
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