MASER power comes out of the cold: Researchers demo solid-state MASER capable of operating at room temperatures

August 15, 2012, National Physical Laboratory
MASER power comes out of the cold
The MASER core - a sapphire ring containing a reddish pink crystal that amplifies microwaves to create a concentrated beam.

Scientists from the National Physical Laboratory (NPL) and Imperial College London demonstrate, for the first time, a solid-state 'MASER' capable of operating at room temperature, paving the way for its widespread adoption - as reported in the journal Nature.

MASER stands for Microwave Amplification by Stimulated Emission of Radiation. Devices based on this process and known by the same acronym were developed by scientists more than 50 years ago, before the first LASERs were invented. Instead of creating intense beams of light, as in the case of LASERs, MASERs deliver a concentrated beam of microwaves.

Conventional MASER technology works by amplifying microwaves using crystals such as ruby - this process is known as 'masing'. However, the MASER has had little technological impact compared to the LASER because getting it to work has always required extreme conditions that are difficult to produce; either extremely low pressures, supplied by special vacuum chambers and pumps, or freezing conditions at temperatures close to absolute zero (-273.15 °C), supplied by special refrigerators. To make matters worse, the application of strong magnetic fields has often also been necessary, requiring large magnets.

Now, the team from NPL and Imperial have demonstrated masing in a solid-state device working in air at room temperature with no applied magnetic field. This breakthrough means that the cost to manufacture and operate MASERs could be dramatically reduced, which could lead to them becoming as widely used as LASER technology.

The researchers 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.

Dr Mark Oxborrow introduces the paper and discusses the MASER.

Dr Mark Oxborrow, co-author of the study at NPL, says:

"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."

Professor Neil Alford, co-author and Head of the Department of Materials at Imperial College London, adds:

"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."

Conventional MASER technology works by amplifying microwaves using hard inorganic crystals such as ruby. However, masing only works when the ruby is kept at a very low temperature. The team in this new study have discovered that a completely different type of crystal, namely p-terphenyl doped with pentacene, can 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 - making it look just like ruby!

The twin challenges the team currently face are getting the MASER to work continuously, as their first device only works in pulsed mode for fractions of a second at a time. They also aim to get it to operate 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. They will also focus on creating new designs that could make the MASER smaller and more portable.

The research was funded by the Engineering and Physical Sciences Research Council and, at NPL, through the UK's National Measurement Office.

The full paper, 'Room-temperature solid-state maser', was published in Nature on 16 August 2012.

Explore further: Most distant detection of water in the Universe

More information: "Room-temperature solid-state maser", published in Nature 16 August 2012. … ull/nature11339.html

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not rated yet Aug 15, 2012
"...and better radio telescopes for potentially detecting life on other planets."

How can a microwave production device help to make a more sensitive radio telescope?
5 / 5 (4) Aug 15, 2012
How can a microwave production device help to make a more sensitive radio telescope?
Presumably, the maser would be used as a direct amplifier for weak microwave signals received by the radio-telescope (as opposed to converting such weak signals to electrical ones, and then amplifying those together with the noise introduced by the conversion.) Of course, it would need to be a fairly broad-band or tunable amplifier; otherwise it won't be very useful for general science.
5 / 5 (2) Aug 16, 2012
they can pop corn one kernel at a time!

not rated yet Aug 18, 2012
Oxborrow just came across a decade-old publication by Japanese researchers suggesting that when the electrons in pentacene are excited by a laser, they configure such that the molecule could work as a maser, possibly even at room temperature. The pentacene-terphenyl system is studied systematically from this perspective. The pentacene molecular resonance when in diluted crystal form like the one discovered, resonates at a natural triplet state transition and it accumulates energy during this. At 1.5 GHz this energy represents a spectrum, that is similar to the one used by microwave oven, bluetooth links and other consumer electronics. The significance of this discovery is that triplet state transitions can achieve population inversion when in a pulsed mode.
not rated yet Aug 18, 2012
A more illustrative explanation provides the snapshot of pentacene molecule, made recently with atomic force microscopy. You can see, that this molecule isn't flat, it's bent like the lid of can because of repulsive forces of excessive electrons covering both sides of it. If you press such a lid, a typical click noise emerges and the bump of lid will get the opposite curvature because of potential barrier existing there. It means, that the flat molecule can accumulate some energy, if you remove some electron from its surface with photoelectric effect temporarily and it can be discharged, when the excited electrons are released back. The quite similar principle has been used with ammonia molecules in first maser generations and now it has been used in solid phase with pentacene molecules.
not rated yet Aug 18, 2012
That video really gave me the shudders.

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