Paving the way for optical on-chip data communication
A team of physicists from the University of Würzburg is hard at work developing technology that could one day allow for the creation of nanoscale antennas with remarkable data transfer properties. Theoretically, these nanoscale-sized directional antennas would have the power to share data between different core processors at the speed of light.
Creating the World’s First Electrically Powered Yagi-Uda Antenna
In a paper published in the journal Nature Communications, physicists explained how they were able to generate directed infrared light with the help of an antenna that is both electrically driven and made out of gold. But this was no typical antenna; known as a Yagi-Uda antenna after the researchers who invented it back in the 1920s, this device has a few special features that set it apart.
The antenna works thanks to an AC voltage, which is applied directly to the structure. This causes the electrons in the antenna to vibrate, which in turn causes the antenna to send out electromagnetic waves. But unlike traditional antennas, the radiated waves created by a Yagi-Uda antenna do not distribute evenly in all directions. Thanks to the use of special elements, scientists can direct the radiated waves in a specific direction, allowing for constructive interference from one direction only; all other directions would result in destructive interference. The same would apply if the antenna operated as a receiver – it would only be capable of taking in light from that one direction. Designing such a singular antenna was no easy feat for scientists, who had to create an unorthodox production technique to make their theory work.
“We bombarded gold with gallium ions which enabled us to cut out the antenna shape with all reflectors and directors as well as the necessary connecting wires from high-purity gold crystals with great precision.”Professor Bert Hecht, Chair of Experimental Physics 5 at the University of Würzburg
Physicists then took a gold nano particle and placed it directly into the active element, taking care to ensure it was simultaneously touching one wire of the element and remaining exactly one nanometer away from the other wire in the device. This narrow gap can be crossed by electrons once voltage is applied, resulting in something known as quantum tunneling. The end result is a powerful, incredibly small antenna capable of emitting in a specific direction.
An open road toward highly directive optical antennas
While this is all impressive, physicists have a long way to go before their work can be used in practical applications. Not only is the team of researchers working on improving the stability of their new antenna, they still have to create its counterpart — one that can receive light signals.