Seminars

Graphene to amplify the signals from GHz to THz

According to a team of scientists, graphene is capable of converting frequencies that far exceed the GHz to which we are limited today.

Graphene, a layer of carbon atoms arranged in hexagons and an atom thick, is the thinnest and most resistant material known to man and, in addition, an excellent conductor of heat and electricity. In 2004, it was discovered how to extract it from graphite and since then it has opened a whole range of new scientific and technological possibilities. During the last decade, many have predicted that its unique structure would make it especially effective in converting optical or electronic signals into signals at much higher frequencies. However, attempts to prove it have not paid off.

Now, for the first time, a team of scientists, two of whom are supported by the EUCALL European funded project, has shown that graphene is capable of converting electronic signals to the range of terahertz, that is, billions of cycles per cycle. second. The findings of this team were presented in a study published in the journal Nature.

The electronic components based on silicon that are used today generate frequencies in the GHz range, that is, billions of cycles per second. The scientists in charge showed that graphene is capable of converting signals at these frequencies into others at frequencies a thousand times higher than those created by silicon.

This is so thanks to the highly efficient nonlinear interaction between light and matter that occurs in graphene. The researchers in charge of the study used graphene with a large amount of free electrons that were originated by the interaction between graphene and the substrate on which it was deposited. When a pulsing electric field at room temperature excites these electrons, they quickly share their energy with electrons trapped in the material. These electrons react in turn as a heated fluid, changing from liquid phase to vapor from inside the graphene in billions of a second. This transition generates rapid and powerful changes in the conductivity of the material and multiplies the frequency of the original GHz pulses.

The frequencies of the original electromagnetic pulses that were generated in the TELBE terahertz facility of the HZDR were between 300 and 680 GHz. The scientists converted them into signals three, five and seven times the original frequency. “This efficiency in the conversion is remarkably large, especially if we take into account that the electromagnetic interaction takes place in a layer of an atom of thickness”, the authors clarify in their study.

The revolutionary discovery supported by EUCALL (European Cluster of Advanced Laser Light Sources) makes graphene a promising candidate for use in the nanoelectronics of the future.

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