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MOSCOW, September 29. /TASS/ Researchers from Laboratory of 2D Materials’ Optoelectronics, Institute of Radioengineering and Electronics at Moscow Institute of Physics and Technologies (MIPT), and Tohoku University (Japan) have found a way of creating plasmon generator which is the key building block for the future of optoelectronics. To achieve this goal, the scientists suggested using graphene, the MIPT’s press service said.
Plasmon is a quasi-particle which is a "mixture" of oscillating electrons and coupled electromagnetic field on the metal surface. Plasmons can be used to generate, transmit, and receive signals in integrated circuits. They can act as mediators between electrons and light waves in photodetectors. Plasmons’ particular features makes the plasmon-based devices for transmitting information by far, more compact than their photonic counterparts, which use light particles as a basis.
To transmit the signal with the plasmons, an appropriate conductive plane is needed. The researchers suggested utilizing graphene, a one-atom-thick layer of carbon atoms, which can be obtained by slicing graphite crystals. The researchers have come up with the idea to construct a "layer-cake" comprising two graphene layers separated by a thin layer of tungsten disulphide. The resulting device is somewhat similar to a laser in its operating principle, but it creates a plasmon current, but not a photon current as in a laser. This plasmonic "laser" has been called SPASER (surface plasmon amplification by stimulated emission of radiation).
Dmitry Svintsov, one of the principle authors of the study, clarified that the tungsten disulphide acts as a gain medium which is a source of plasmons, whereas the graphite layers replace mirrors of classic lasers. When the electric current passes through the gain medium, plasmons are generated, which further are reflected from the graphene layers and amplified. Additionally, Svintsov commented that the generated plasmons could be uncoupled from the graphene layers and proliferate as photons in free space. This allows for creating tunable sources of terahertz and far infrared radiation.
The compact graphene-based plasmon generator created by Dmitry Svintsov, Zhanna Devizorova, Victor Ryzhii, and Taiichi Otsuji was presented with the Alferov’s Foundation Young Scientist Award at the 24th International Symposium Nanostructures: Physics and Technology which was held in Saint Petersburg in July 2016.
The results of the study have been published in the journal Physical Review B.