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Penn Engineers Efficiently 'mix' Light at the Nanoscale

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Light emitted from the underside of the cavity in this nanowire system.

Light emitted from the underside of the cavity. The dotted outline represents the orientation of the cadmium sulfide nanowire.

Credit: Penn News

Scientists say photonic-based systems could replace electronic systems as a way to make computer components smaller, faster, and less power-hungry.

Although the fundamentals of computation, mixing two inputs into a single output, require too much space and power when done with light, a team at the University of Pennsylvania (Penn) say they have found a solution. The researchers say they engineered a nanowire system that could pave the way for combining two light waves to produce a third with a different frequency, and using an optical cavity to amplify the intensity of the output to a usable level. The researchers partially wrapped a cadmium sulfide nanowire in a silver shell that acts in the manner of an echo chamber. By changing the polarization of the light as it enters the nanowire, they are better able to confine it to the frequency-altering, nonlinear part of the device and maximize the intensity while generating the second harmonic, which means doubling the frequency of the light wave.

Frequency mixing was possible on the nanoscale with very high efficiency. "Ultimately, we want to be able to tune the light to whatever frequency is needed, which can be done by altering the size of the nanowire and the shell," says Penn professor Ritesh Agarwal.

The optical cavity increased the output wave's intensity by more than 1,000 times.

From Penn News
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