The Leeds team, led by Professors Edmund Linfield and Giles Davies from the Faculty of Engineering, has recorded the highest operating temperature for a terahertz quantum cascade laser – a technology that scientists believe may unlock the potential of the terahertz frequency range.
Professor Linfield explains: “The potential uses for terahertz technology are huge, but at the moment they are limited to niche applications in, for example, the pharmaceutical industry and astronomy, as the current systems on the market are expensive and physically quite large. The availability of cheap, compact systems would open up a wide range of opportunities in fields including industrial process monitoring, atmospheric science, and medicine.”
Key to exploiting terahertz technology is the production of handheld devices, and one specific type of laser – the quantum cascade laser – will allow the creation of a terahertz device that is small and portable. The problem is, at the moment this type of laser will only function at temperatures of minus 100°C.
So the challenge is to create a terahertz quantum cascade laser which will work at room temperature. While the groups from Leeds and Harvard are still a way off from this, they have succeeded in increasing the laser’s operating temperature by nearly ten degrees, and believe they have the means to improve it yet further.
“We hope to obtain further advances by optimising the methods we used to create the device,” explains Professor Linfield. “We have some radically new design ideas, and also believe that we can make significant improvements in the way we fabricate the lasers.”
Terahertz quantum cascade lasers are created by building layers of compounds of aluminium, gallium and arsenic one atomic monolayer at a time, through a process known as molecular beam epitaxy. Leeds’ Faculty of Engineering is one of a small number of laboratories in the world actively ‘growing’ terahertz quantum cascade lasers at this time, using a molecular beam epitaxy system purchased through the Science Research Infrastructure Fund (SRIF).
In molecular beam epitaxy, the chemicals evaporate from heated cells, and land on a heated, rotating, substrate. Minute changes in temperature, combined with a set of shutters that block the chemical beams, enable the team to adjust the amount of each chemical which is deposited on the substrate, gradually building up the layers they need. To ensure the device works perfectly, there must be no pollutants, so the process is carried out under ultra-high vacuum conditions, approaching the vacuum levels found in outer space.
The equipment and expert use of it by Professor Linfield and his team enabled them to create a device of superior quality. They now believe that they can bring handheld terahertz technology a step closer still.
The research, carried out in collaboration with the group of Professor Frederico Capasso at Harvard University, and supported by the Engineering and Physical Sciences Research Council (EPSRC) is published in Optics Express ( Vol. 16, Issue 5, pp. 3242-3248).
Jo Kelly | alfa
Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State
What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy