德研究人员开发出基于石墨烯的太赫兹激光器

ssions about 100 femtoseconds in length, suitable for a fast pulsed laser. Many applications could benefit from a terahertz laser, including research into high-temperature superconductors, according to Gierz who performed the work with colleagues at the Central Laser Facility in Harwell, England, and the Max Planck Institute for Solid State Research in Stuttgart, Germany.

"High-temperature superconductors -- but also other materials -- exhibit numerous excitations in the terahertz range," said Gierz. "Aside from fundamental research, terahertz light sources have numerous other applications."

So far, Gierz and her research group at Max Planck have surmounted two of the three hurdles to producing a graphene-based terahertz laser, with the last element on their to-do list.

"A laser consists of three parts: an active medium for light amplification, a pump source that supplies the power, and a laser cavity," Gierz told us. "We have demonstrated the first and second. The cavity, however, needs to be designed."

Gierz and colleagues also tried to show that graphene could be used in a manner opposite to a laser, that is, for light harvesting in solar cells. What they found was that one graphene electron can potentially release multiple photons for stimulated emission in a laser, but the opposite process -- one photon releasing multiple electrons as is necessary for solar cells -- was not observed, leading the group to believe that graphene will not work for photovoltaics.

By R. Colin Johnson