Researchers at the University of Leeds and the University of Nottingham have discovered ultra-fast modulation scombined with the power of sound and light waves, and claim a breakthrough in the control of terahertz quantum cascade lasers,media reported. It can transmit data at a rate of 100 gigabits per second, about a thousand times faster than fast Ethernet running at 10,000 Megahz, the team said.
It is understood that terahertz quantum cascade lasers emit light within the terahertz range of the electromagnetic spectrum and are used in chemical analysis in the field of spectroscopy. Lasers can eventually also provide ultra-fast, short-jump wireless links, in which case large data sets must be transmitted between hospital campuses, between universities, or in satellite communications.
In order to be able to send data at these increased speeds, lasers need to be modulated very quickly: turn on and off or generate about 100 billion pulses per second. John Cunningham, professor of nanoelectronics at the University of Leeds, commented: “This is an exciting study, and at the moment, systems used to modulate quantum cascades of lasers are powered by electricity, and the same electronic device that provides modulation often hinders modulation speed.” The mechanism we are developing relies instead on sound waves. “Quantum cascading lasers are very effective. When an electron passes through the optical component of a laser, it passes through a series of “quantum traps”, in which the electron’s energy level drops and the light-nin or photoenergy pulse is emitted.
It is reported that during modulation is controlled by an electron capable of emitting multiple photon processes. Researchers at the University of Leeds and the University of Nottingham did not use external electronic devices, but instead used sound waves to vibrate the quantum traps inside the quantum cascade laser. Sound waves are produced when pulses from another laser hit the aluminum film, causing the film to expand and contract, thus emitting mechanical waves through quantum cascading lasers.
Tony Kent, a professor of physics at the University of Nottingham, says: “Essentially what we do is use sound waves to shake the complex electron state inside a quantum cascade laser, and then we can see that its terahertz output is altered by sound waves. Professor Cunningham added, “We didn’t get there to stop completely and start flowing, but we were able to keep light output at a few percentage points, which was a good start.”