First microwave laser to operate at room temperature

August 17, 2012 // Nick Flaherty

Scientists in the UK have developed the first solid-state MASER to operate at room temperature, paving the way for its widespread adoption.

The researchers from the National Physical Laboratory (NPL) and Imperial College London suggest that room-temperature MASERs could be used to make more sensitive medical instruments for scanning patients, improved chemical sensors for remotely detecting explosives; lower-noise read-out mechanisms for quantum computers and better radio telescopes for potentially detecting life on other planets.The microwave equivalent of a laser, masers deliver a concentrated beam of microwaves by amplifying microwaves using hard inorganic crystals such as ruby. But they have always required extreme conditions such as extremely low pressures or temperatures close to absolute zero ( -273.15°C), as well as strong magnetic fields from large magnets.
The team have demonstrated pulse masing in a solid-state device working in air at room temperature with no applied magnetic field. This could dramatically reduce the cost to manufacture and operate a MASER, which could lead to them becoming as widely used as laser technology in a wide range of applications.
"For half a century the MASER has been the forgotten, inconvenient cousin of the laser. Our design breakthrough will enable MASERs to be used by industry and consumers," said Dr Mark Oxborrow, co-author of the study at NPL.
"When lasers were invented no one quite knew exactly how they would be used, and yet the technology flourished to the point that lasers have now become ubiquitous in our everyday lives. We've still got a long way to go before the MASER reaches that level, but our breakthrough does mean that this technology can literally come out of the cold and start becoming more useful," said Professor Neil Alford, co-author and Head of the Department of Materials at Imperial College London.
The team used a completely different type of crystal, namely p-terphenyl doped with pentacene, to replace ruby and replicate the same masing process at room temperature. As a curious twist, the pentacene dopant turns the otherwise colourless p-terphenyl crystal an intense reddish pink.
The first device only works in pulsed mode for fractions of a second at a time. They aim to get it to operate continously over a range of microwave frequencies, instead of its current narrow bandwidth, which would make the technology more useful.
In the long-term, the team have a range of other goals including the identification of different materials that can mase at room temperature while consuming less power than pentacene-doped p-terphenyl. The team will also focus on creating new designs that could make the MASER smaller and more portable.
www.npl.co.uk

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