Search Menu
Photonics Media Photonics Marketplace Photonics Spectra BioPhotonics EuroPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Graphene Phenomenon Could Enable New Lasers

Facebook Twitter LinkedIn Email Comments
DRESDEN, Germany, Nov. 25, 2014 — Understanding the dynamics of electrons in graphene under strong magnetic fields could lead to development of new types of broadband lasers.

An international team led by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) exposed graphene to a 4-Tesla magnetic field, which forced electrons in the material into certain energy states called Landau levels.

These energy levels were then examined with a free-electron laser.

Electron redistribution through Auger scattering has been discovered in graphene.
Electron redistribution through Auger scattering has been discovered in graphene. Courtesy of Voigt/HZDR.

“The laser pulse excites the electrons into a certain Landau level. A temporally delayed pulse then probes how the system evolves,” said doctoral candidate Martin Mittendorff. The researchers found the Landau level into which new electrons were pumped by the laser gradually emptied in an unexpected way, and that collisions between electrons were the cause.

“Imagine a librarian sorting books on a bookshelf with three shelves,” Dr. Stephan Winnerl said by way of analogy. “She places one book at a time from the lower shelf onto the middle shelf. Her son is simultaneously ‘helping’ by taking two books from the middle shelf, placing one of them on the top shelf, the other on the bottom. The son is very eager and now the number of books on the middle shelf decreases even though this is precisely the shelf his mother wishes to fill.” Winnerl said the researchers did not expect the effect, known as Auger scattering, to be so strong or to deplete an energy level.

Free-electron lasers at HZDR.
With intense light from the HZDR’s free-electron lasers, materials can be examined on the atomic level. Courtesy of Frank Bierstedt/HZDR.

While a number of effects have been discovered with graphene in magnetic fields, the dynamics of electrons in such a system have not been studied before. The researchers said the phenomenon they discovered could enable lasers that can produce light with arbitrarily adjustable wavelengths in the IR and terahertz ranges.

“Such a Landau-level laser was long considered impossible, but now with graphene, this semiconductor physicists’ dream could become a reality,” Winnerl said.

The work was funded by the DFG German Research Foundation. The research was published in Nature Physics (doi: 10.1038/nphys3164). 

For more information, visit
Nov 2014
Research & TechnologylasersmaterialsEuropeelectronsgrapheneLandau levelsHelmholtz-Zentrum Dresden-RossendorfHZDRMartin MittendorffStephan Winnerl

Photonics Spectra Optics Conference 2022
view all
Search more than 4000 manufacturers and suppliers of photonics products and services worldwide:

back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2021 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x We deliver – right to your inbox. Subscribe FREE to our newsletters.
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.