A report recently published in Nano Letters, describes the work done by a team of NIM researchers led by Hubert Krenner and Achim Wixforth from the University of Augsburg and Gregor Koblmüller, Gerhard Abstreiter and Jonathan Finley from the Walter Schottky Institut at TU Munich.
The research discovered that nanowires will not only conduct electric currents but also emit light.
Light beamed from an individual nanowire can be turned on and off at regular intervals faster than a nanosecond. The team discovered that a radio frequency sound wave in a hybrid product they built could pass along a nanowire, switching its light emission on and off.
The geometry of the nanowire purposely increased or decreased the turning on or off of the light from the nanowire. The effect was strongest when the sound wave moved along the nanowire axis. The emission remained mostly unchanged with a perpendicular alignment. This was due to the charges, electrons and holes being separated, which were earlier produced by a short laser pulse.
The sound wave fragments the two conductors along its normal route and isolates them in pockets divided by half its wavelength. This spatial isolation reduces light generation and causes a modulation of the signal tracked. The sound wavelength is more than the nanowire diameter but shorter in length, so this fragmentation is possible only in the event of the sound wave travelling along the axis of the nanowire. The sound wave moves down the nanowire and transmits charges.
This feature will enable charges to be moved to a quantum dot that can be created in the nanowire through a short piece of another substance. Quantum dots produce light as single quanta or photons, repeated at regular intervals pre-determined by the sound wave frequency. Such photons are needed to implement safe quantum cryptography protocols.