Nanotubes could enable electro-optical conversion

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By integrating carbon nanotubes into a nanostructured waveguide, researchers at Karlsruhe Institute of Technology (KIT) have developed a miniaturised switching element that converts electric signals into clearly defined optical signals.

“The nanostructures act like a photonic crystal and allow for customising the properties of light from the carbon nanotube,” said researchers Felix Pyatkov and Valentin Fütterling. “In this way, we can generate narrowband light in the desired colour on the chip.”

Processing the waveguide precisely defines the wavelength at which the light is transmitted. Using electron beam lithography, waveguides several microns long are equipped with nanometres sized cavities and these determine the waveguide’s optical properties. The carbon nanotubes integrated into the waveguide act as a small light source. When a voltage is applied, they produce photons.

According to the team, the electricity/light signal converter meets the requirements of the next generation computers. The signal converter is said to ‘bundle’ the light about as strongly as a laser and to respond to variable signals with high speed. The team says that, already, its optoelectronic components can be used to produce light signals at GHz frequencies.