Swiss develop optical circuit based on silver atom




Swiss scientists have made a digital circuit at the atomic level. It is an optical modulator which can operate on the basis of a single silver atom. The switch does not work quickly and is difficult to do, but want to improve the scientists.

The research team from the Eidgenössische Technische Hochschule in Zurich speaks of the smallest integrated optical switch so far. The modulator is even smaller than the wavelength of the light used, something that team leader Juerg Leuthold, a professor in the field of Photonics and Communication, until recently thought possible.

The modulator consists of two small plates, one of silver and one of platinum. Which are placed on an optical light path of silicon, in which they are next to each other only a few nanometers. The silver plate additionally has a bulge until just next to the platinum leaving a tiny passage. The researchers then create light with a fiber to the passage of the light path.

Under the influence of the light are formed at the interface of the silver and platinum plasmons. The collective vibration of the electrons thereby oscillates at the frequency of the light, but with a much smaller amplitude. As a result, the elektronenoscillaties fit through the small passage, and at the other end, they can be converted back into optical signals.

In order to make the switch system, a voltage must be applied to the silver image. This ensures that a single silver atom, or at most a few atoms, proceed to the point of the passage and connect the silver and platinum plate with each other, whereby there can be done by an electric current. Once the voltage is reduced, the atom returns and the passage is free again for the plasmons. This creates an on and off millions of times which these researchers can be used.

“This allows us to create a digital circuit such as a transistor,” said Leuthold. The switch operates at room temperature, but functions for a modulator still slow: in megahertz level or lower. Moreover, the production of the system fails, only one in six times. The team will now work towards use terahertz level and improve lithografieprocedé. Within a few years a practical implementation to be completed.

The research of the ETH Zurich under the name Atomic Scale Plas Monic Switch published in Nano Letters.


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