Graphene sets the stage for the next generation of THz astronomy detectors

phys.org | 10/31/2017 | Staff
roxy2707 (Posted by) Level 3
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Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.

Beyond superconductors, there are few materials that can fulfill the requirements needed for making ultra-sensitive and fast terahertz (THz) detectors for astronomy. Chalmers researchers have shown that engineered graphene adds a new material paradigm for THz heterodyne detection.

Graphene - Material - Conductor - Electricity/heat - Electrons

"Graphene might be the only known material that remains an excellent conductor of electricity/heat even when having, effectively, no electrons. We have reached a near zero-electron scenario in graphene, also called Dirac point, by assembling electron-accepting molecules on its surface. Our results show that graphene is an exceptionally good material for THz heterodyne detection when doped to the Dirac point," says Samuel Lara-Avila, assistant professor at the Quantum Device Physics Laboratory and lead author of the paper.

The experimental demonstration involves heterodyne detection, in which two signals are combined, or mixed, using graphene. One signal is a high intensity wave at a known THz frequency, generated by a local source (i.e. a local oscillator). The second is a faint THz signal that mimics the waves coming from space. Graphene mixes these signals and then produces an output wave at a much lower gigahertz (GHz) frequency, called the intermediate frequency, that can be analyzed with standard low noise gigahertz electronics. The higher the intermediate frequency can be, the higher bandwidth the detector is said to have, required to accurately identify motions inside the celestial objects.

Sergey

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(Excerpt) Read more at: phys.org
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