December 13, 2014

Revving Up Fluorescence for Superfast LEDs

(October 13, 2014)  Duke University researchers have made fluorescent molecules emit photons of light 1,000 times faster than normal—setting a speed record and making an important step toward realizing superfast light emitting diodes (LEDs) and quantum cryptography.

This year's Nobel Prize in physics was awarded for the discovery of how to make blue LEDs, allowing everything from more efficient light bulbs to video screens. While the discovery has had an enormous impact on lighting and displays, the slow speed with which LEDs can be turned on and off has limited their use as a light source in light-based telecommunications.

In an LED, atoms can be forced to emit roughly 10 million photons in the blink of an eye. Modern telecommunications systems, however, operate nearly a thousand times faster. To make future light-based communications using LEDs practical, researchers must get photon-emitting materials up to speed.

In a new study, engineers from Duke increased the photon emission rate of fluorescent molecules to record levels by sandwiching them between metal nanocubes and a gold film.

The results appear online October 12 in Nature Photonics.

“One of the applications we’re targeting with this research is ultrafast LEDs,” said Maiken Mikkelsen, an assistant professor of electrical and computer engineering and physics at Duke. “While future devices might not use this exact approach, the underlying physics will be crucial.”

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