Feb. 11 (UPI) -- Scientists have developed a way to control terahertz quantum cascade lasers using light and sound. The breakthrough could enable record data transfer speeds.
Terahertz quantum cascade lasers produce light in the terahertz range of the electromagnetic spectrum. In addition to enabling high speed data transfers, the technology could be used in the field of spectroscopy for chemical analysis.
In order for terahertz quantum cascade lasers to transfer data at high speeds, the lasers must be rapidly modulated. They have to be switched on and off roughly 100 billion times every second.
Until now, scientists had been unable to develop a method for such rapid modulation.
To toggle the terahertz laser light at record speeds, scientist at the University of Leeds and University of Nottingham used a combination of light and sound waves.
"This is exciting research," John Cunningham, professor of nanoelectronics at Leeds, said in a news release. "At the moment, the system for modulating a quantum cascade laser is electrically driven -- but that system has limitations."
In a quantum cascade laser, as an electron passes through the optical component, it passes through a succession of quantum wells, each well causing the energy level of the electron to drop and a photon to be released.
It is this process of electron-induced photon emissions that dictate modulation.
To manipulate the process in the new terahertz quantum cascade laser, researchers used acoustic waves. Scientists precisely produced sound waves by pointing a laser onto an aluminium film. The resulting sound wave works to vibrate the laser's quantum wells, causing ultra-fast modulation.
"Essentially, what we did was use the acoustic wave to shake the intricate electronic states inside the quantum cascade laser," said Tony Kent, professor of physics at Nottingham. "We could then see that its terahertz light output was being altered by the acoustic wave."
Researchers described their breakthrough technology Tuesday in the journal Nature Communications.
The laser still needs work before it can be incorporated into communication technologies or used for spectroscopic imaging and analysis.
"We did not reach a situation where we could stop and start the flow completely, but we were able to control the light output by a few percent, which is a great start," Cunningham said. "We believe that with further refinement, we will be able to develop a new mechanism for complete control of the photon emissions from the laser, and perhaps even integrate structures generating sound with the terahertz laser, so that no external sound source is needed."