The room-temperature maser relies on a crystal of organic molecules excited with an optical laser.
Image: NPL
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By Geoff Brumfiel of Nature magazine
Using spare chemicals, a laser bought on eBay and angst from a late-night argument, physicists have got the world's first room-temperature microwave laser working.
The achievement comes nearly 60 years after the first clunky versions of such devices were built, and could revolutionize communication and space exploration. The work is published this week in Nature.
Before there were lasers, there were microwave lasers, or masers. First conceived in the Soviet Union and the United States during the 1950s, early maser machines were the size of a chest of drawers. They produced only a few nanowatts of power, severely limiting their usefulness.
Because of this impediment, most in the field gave up on masers and moved on to lasers, which use the same principles of physics, but work with optical light instead of microwaves. Lasers are now used in applications ranging from eye surgery to CD players.
The poor maser lived on in obscurity. It found only a few niche uses, such as boosting radio signals from distant spacecraft — including NASA's Curiosity Mars rover. Those masers work only when cooled to less than ten degrees above absolute zero, and even then they are not nearly as powerful as lasers.
Pink power
But Mark Oxborrow, a physicist at the UK National Physical Laboratory in Teddington, wondered whether a crystal containing the organic molecule pentacene might offer a breakthrough. He 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.
Oxborrow enlisted two colleagues — materials scientists Jonathan Breeze and Neil Alford from Imperial College London — and got to work on testing this suggestion. He borrowed some spare pentacene from a lab at Imperial, and cooked it with another organic molecule known as p-terphenyl. The result was a pink crystal a few centimeters long.
Next, the team needed a powerful laser. Oxborrow located an old medical laser on eBay and drove to a warehouse in north London to pick it up. But the researchers were filled with doubts — the whole thing seemed too easy. Oxborrow admits that he was skittish about the experiment. "For about three days, I could have done it, but I didn't have the nerve to switch on that button," he says.
The final impetus came from an argument with his wife. Whereas less well-behaved people might have wallowed in the pub, "I went to the lab as a bit of therapy", says Oxborrow. "I said, 'Oh well, what the hell, let's just try it." And it worked on the first go.
Excited state
The laser light excited the pentacene molecules to an energy level known as a metastable state. Then a microwave passing through the crystal triggered the molecules to relax, releasing a cascade of microwaves of the same wavelength.
It was the same principle as an optical laser. "The signal that came out of it was huge," says Oxborrow, about a hundred million times as powerful as an existing maser. Alone in his lab, "I swore a lot and walked around the corridor about five times talking to myself".
"It is a considerable achievement," says Cyril Hilsum, a retired physicist who helped to develop some of the earliest solid-state lasers. "It shows great originality and great ability."
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16 Comments
Add CommentCould this be used to beam power from orbiting solar panels to earth?
Reply | Report Abuse | Link to thisThis would be great for plasma research, especially plasma engines. Microwaves (especially at high energy) are perfect for that.
Reply | Report Abuse | Link to thisGood work, Dr. Oxborrow. It makes me think how many correct conjectures and ideas are in old publications forgotten and collecting dust.
Reply | Report Abuse | Link to thisHow about Fusion control?
Reply | Report Abuse | Link to thisYou make us proud. Bold experiment!
Reply | Report Abuse | Link to thisIts amazering and shows a host of future applications not yet thought of. For some of you who want to see an earth based mazer future application may be used to beam energy from one place to another one anywhere on earth first thought of in 2003 go here.
Reply | Report Abuse | Link to thishttp://shineinnovations.com/6112.html
Imagine processing natural gas at the site like from Alaska's oilfields that it is processed and turned into energy then beamed to anywhere on earth. We wouldn't have to build a 100 billion dollar pipeline from nowhere to do this just launch a inflatable reflective device into geostationary orbit.
At last. Some real science reported in a timely manner. Is this a sign of the return of the good old days at SCIAM?
Reply | Report Abuse | Link to thisA maser is not a laser! laser=LIGHT maser=MICROWAVE
Reply | Report Abuse | Link to thisThey are NOT the same thing. This title is WRONG!
A maser is NOT a microwave laser - period!
What is it exactly? Or are you saying Microwaves are not photons?
Reply | Report Abuse | Link to thisI agree with Ogltree's comment completely:
Reply | Report Abuse | Link to thisThe term "microwave laser" is completely dumb and inane.
A maser is a maser and an laser is a laser.
Furthermore, this part of the
"First Practical Maser Is Built"
Practical masers have been used for decades. Practical masers are used every day in the Deep Space Network, the Arecibo Observatory, and other places, where their vital function is as very-low-noise microwave amplifiers. It is true that these practical and useful masers operate at cryogenic temperatures.
However, those cryogenic masers do not necessarily have to work at the temperatures of liquid helium or liquid hydrogen. Liquid nitrogen and liquid argon also work.
The term "microwave laser" is genuinely bad.
Reply | Report Abuse | Link to thisThe maser was invented first, and so the term "optical maser" was used for a short span of years".
However, I have read that this terminology was used mostly by a party to a legal case in the USA wanting to drag things out in his favor.
Charles H. Townes invented the maser first, and then he insisted on "optical maser" for years. However, Thomas H. Maiman (of the Hughes Research Labs) eventually won out and he was granted the U.S. Patent for the LASER, which Maiman had invented in 1960.
There were endless other arguments before the patent was granted years later, and by then, Maiman had spent most of his money on lawyers' fees, and he was an old man, too. He died in about 2007 -- a long time after Townes died, but there were others involved, including a man named Gould.
Anyway, "microwave laser" is a bunch of baloney because the maser was invented earlier, by C. H. Townes.
Please don't argue about technicalities, guys.
Reply | Report Abuse | Link to thisI think a cheap, room temperature maser is hot stuff regardless of what you call it. Deep Freeze masers may be quite useful for a number of things, but Kitchen Counter operation certainly adds a whole new layer of practicality.
First, Carlyle is so right: about a week ago, the list of items on the daily newsletter read like a parody of a science publication-turned-mush-brained-with-eco-advocacy.
Reply | Report Abuse | Link to thisSecond and third, the clever Japanese and the inpirational Mrs. Oxborrow are the true generators of this new marvel, midwived by the good if clumsy and dilatory Dr. Oxborrow.
You're right. LASER = Light Amplification by Stimulated Emission of Radiation. MASER = Microwave Amplification by Stimulated Emission of Radiation. It's not strictly correct to call a maser a "microwave laser".
Reply | Report Abuse | Link to thisLet's see.
Reply | Report Abuse | Link to thisIf you take a particular substance and hit it with a laser while bombarding it with microwaves you get a focused beam of microwaves amplified by several orders of magnitude.
Hmmm.
microwaves...laser....beam...amplification.... Sounds like a microwave laser operation to me. But then what do I know?
Chill people - it's called writing for your audience, not scientific heresy.
Reply | Report Abuse | Link to thisMost people know what a laser is. Very few people know what a maser is. Describing a lesser known object by comparison to a better known object is called "analogy" and it's pretty much a staple of science writing. It's essential when the purpose of your writing is to inform people about complex or technical topics they may have little or no familiarity with. SciAm is, after all, a freaking MAGAZINE not a peer-reviewed science journal.
Congratulations that you know what a maser is. You are smart and special. For the rest of us, the "microwave laser" analogy is helpful and informative, and I don't think that anyone, after reading this, thinks that a maser is a device that turns microwaves into visible light and then amplifies it.