An Antenna for Visible Light

[] An antenna for visible light, analogous to antennas for radio waves, can now be made with carbon nanotubes, and could offer yet another venue for solar photovoltaic research and development. In a radio antenna, whose size is equal to the wavelength of the incoming wave or a fair fraction of it, the wave excites electrons into meaningful currents . Such a response, amplified and tuned, is the backbone of radio and TV broadcasting. At optical wavelengths, where the wavelength is hundreds of nm, this is harder to do. Nevertheless, a rudimentary antenna effect for visible light has now been observed by scientists at Boston College using an array of carbon nanotubes, in which infalling light excites miniature electrical currents. Possible applications for visible-light antennas? Optical television: a TV signal, superimposed on a laser beam sent down an optical fiber, is demodulated at the customer end by an array of nanotubes (each functionalized by a fast diode). Or efficient solar energy conversion: incoming light is turned into charge which is stored in a capacitor.


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