Quantum laser control breakthrough allows for ultra-fast ethernet speeds

11 Feb 2020

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A breakthrough involving the control of terahertz quantum cascade lasers could improve ethernet speeds 1,000-fold.

Researchers at the University of Leeds have found a way to drastically speed up wireless data transfers across facilities such as hospital campuses or between research facilities on universities following a new breakthrough.

In a paper published to Nature Communications, they explained a new way to control terahertz quantum cascade lasers, which could lead to data transfer rates of 100Gbps. This would be 1,000 times quicker than a fast ethernet connection operating at 100Mbps.

What distinguishes terahertz quantum cascade lasers from other lasers is the fact that they emit light in the terahertz range of the electromagnetic spectrum. They have applications in the field of spectroscopy, where they are used in chemical analysis.

‘This is exciting research’

To be able to send data at speeds of 100Gbps, lasers need to be modulated very rapidly to the point they are switching on and off around 100bn times per second. In this breakthrough, the researchers were able to achieve this by combining the power of acoustic and light waves.

“This is exciting research,” said Prof John Cunningham.

“At the moment, the system for modulating a quantum cascade laser is electrically driven – but that system has limitations.

“Ironically, the same electronics that delivers the modulation usually puts a brake on the speed of the modulation. The mechanism we are developing relies instead on acoustic waves.”

Passing through ‘quantum wells’

In a quantum cascade laser, an electron passing through the optical component of the laser goes through a series of ‘quantum wells’ where the energy level of the electron drops and a photon or pulse of light energy is emitted.

This means that external electronics can be removed from the process and replaced by these acoustic waves generated by the impact of a pulse from another laser on to an aluminium film.

This causes the film to expand and contract, sending a mechanical wave through the quantum cascade laser.

“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.”

Colm Gorey was a senior journalist with Silicon Republic