Super-fast internet breakthrough: scientists use lasers to send data at 100 gigabits per second – 1000 times faster than Ethernet
- British scientists used light pulses in the terahertz range of light waves
- They used sound waves to send around 100 billion light pulses per second
- ‘Terahertz quantum cascade lasers’ could deliver loads of data at high speeds
Scientists have used special lasers to generate ultra-fast data transfer at 100 gigabits per second – a thousand times faster than a fast Ethernet cable.
British scientists have found a way to control ‘terahertz quantum cascade lasers’, which emit light in the terahertz range of the electromagnetic spectrum.
The lasers can offer ultra-fast wireless connections where large amounts of data are transferred to hospital campuses or universities.
Terahertz radiation occupies a space between microwaves and infrared light waves that are known as the ‘terahertz gap’.
The problem with using light in the terahertz gap is that the lasers have to be modulated very quickly – switch on and off or pulse about 100 billion times per second.
Depicted the terahertz quantum cascade laser on its mounting device. Tweezers are also shown for scale
Engineers at the University of Leeds and the University of Nottingham believe they have now found a way to achieve this – by combining light with the power of sound waves.
WHAT ARE TERAHERTZ QUANTUM-CASCADE LASERS?
Terahertz quantum cascade lasers (TQCLs) can cause radiation in the terahertz range of the electromagnetic spectrum.
TQCLs provide high-resolution imaging than microwave ovens and offer images with a higher contrast than X-rays.
They have applications in communication, domestic safety studies, biomedical medicines and quality control.
The terahertz range refers to electromagnetic waves with wavelengths between 3 mm and 30 μm.
The terahertz range has light with longer waves than that of visible light – the light that people can see.
“This is exciting research,” said Professor John Cunningham of the University of Leeds.
“The system for modulating a quantum cascade laser is currently electrically powered – but that system has limitations.
‘Ironically, the same electronics that provide modulation usually slow down the speed of modulation.
“The mechanism that we are developing depends on acoustic waves instead.”
As an electron passes through the optical component of the quantum cascade laser, it goes through a series of “quantum wells” where the energy level of the electron drops and a photon – a pulse of light energy – is emitted.
One electron can emit multiple photons, and this is the process that is controlled during modulation.
Instead of using external electronics, the researchers used acoustic waves to vibrate the quantum wells in the quantum cascade laser, generated by the impact of a pulse from another laser on an aluminum film.
This caused the film to expand and contract and send a mechanical wave through the quantum cascade laser.
“In essence, we’ve used the acoustic wave to shake the complicated electronic states in the quantum cascade laser,” said Tony Kent, professor of physics at the University of Nottingham.
“We could see then that his terahertz light output was changed by the acoustic wave.
The terahertz range refers to electromagnetic waves with frequencies between 100 GHz and 10 THz, or wavelengths between 3 mm and 30 μm, shorter than infrared but longer than microwaves
“This result opens a new field for physics and engineering to come together in the exploration of the interaction of terahertz sound and light waves, which may have real technological applications,” said Professor Kent.
Although the research team could not stop and fully start the power, they managed to control the light output by a few percent – which is a “great start,” said Professor Cunningham.
“We believe that with further refinement we can develop a new mechanism for full control of the photon emissions from the laser, and maybe even integrate structures that generate sound with the Terahertz laser, so that no external sound source is needed.”
The findings were published in the journal Nature communication.