The breakthrough was made thanks to the control of lasers, which make it possible to transmit information at high speed
Terahertz quantum cascade lasersdiffer from other types of lasers in that they emit light in the terahertz range of the electromagnetic spectrum. This type of laser is widely used in the field of spectroscopy, in particular, in chemical analysis.
To send data at these speeds,which terahertz lasers allow, they must be modulated very quickly: turn on and off, that is, pulsate, about 100 billion times per second. Until now, scientists have not been able to put this into practice. But researchers at the University of Leeds succeeded; they used the combined power of acoustic and light waves.
John Cunningham, professor of nanoelectronics atLeeds says: “Currently, a system for modulating a quantum cascade laser is driven by an electric drive, but this method has its limitations. Ironically, the same electronics that provide modulation usually slows its speed. The mechanism we are developing relies on acoustic waves. ”
Instead of using external electronics teamsresearchers from the universities of Leeds and Nottingham used acoustic waves to vibrate quantum wells inside a quantum cascade laser. These waves were generated by the action of a pulse of another laser on an aluminum film, which caused the film to expand and contract, sending a mechanical wave through a quantum cascade laser.
Tony Kent, professor of physics at Nottingham,adds: “Basically, we used an acoustic wave to «shake» complex electronic states inside the quantum cascade laser, and this, in turn, led to the fact that its terahertz light flux was changed by an acoustic wave.”
Professor Cunningham added: “We did not reach a situation where we could stop or completely start the flow, but we were able to control the light output by a few percent, which is already a great start.”