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Graduate students Kale Franz, of Princeton University, and Stefan Menzel, of the University of Sheffield, UK, collaborated to discover a new kind of laser.  (Source: Frank Wojciechowski)

The new laser was discovered when a quantum cascade laser, a nanomachined semiconductor infrared laser, like the one shown here, emitted two beams. The new type of laser uses less power and performs better with increasing temperature, unlike most semiconductor lasers. It could not be explained by previous laser theory.  (Source: Frank Wojciechowski)
Newly discovered laser is more efficient than traditional laser beams could revolutionize sensing, medical technologies

Semiconductor lasers are a critical component to sensors of all sorts, including chemical microsensors and labs-on-a-chip.  They are also critical to many kinds of medical scanners. 

Thus the discovery of a new kind of laser beam may be critical to a great many fields, including air quality monitoring, medical diagnostics, homeland security, and other chemical applications.  The new type of laser was discovered at Princeton University by a pair of graduate students; Kale Franz, graduate student of Princeton's Claire Gmachl at the Mid-Infrared Technologies for Health and the Environment (MIRTHE) center and Stefan Metzel, a University of Sheffield, UK visiting grad student.

The pair, under the guidance of Professor Gmachl, built a small metallic laser device called a quantum cascade laser, only to find that it unexpectedly emitted not one, but two laser beams.  While the first beam was a typical laser beam, the second had unusual properties, including the fact that it required less power to create.  Kale Franz describes, "This discovery provides a new insight into the physics of lasers.  If we can turn off the conventional beam, we will end up with a better laser, which makes more efficient use of electrical power."

Metzel, an intern at Princeton, was intrigued by the second beam's unique properties as he dug into the phenomenon.  The beam, like all lasers consisted of coherent or in ordered photons.  In a laser beam photons move in an ordered fashion, lending lasers their distinctive color, beam, and properties.  Normal light from sun, typical chemical reactions, or electric lamps are disordered. 

It is commonplace to create lasers from gallium arsenide or other semiconductors by passing an electronic current through specially manipulated circuit causing electrons to jump in energy levels, then fall, emitting synchronized photon emissions in the process.  This kind of laser is used in media, laser pointers and other devices.  The Princeton device, the quantum cascade laser, is a specialized form of semiconductor laser built at a nanoscale.  It is one-tenth as thick as a human hair and 3 millimeters long and consists of atom-thick layers of different semiconductors.  These layers emit sequentially synchronized photons.

The second beam on the quantum cascade lasers was identified due to its shorter wavelength than the main beam.  Unlike normal lasers, which weaken at higher temperatures, this laser increased in strength up to a point.  This behavior could not be explained by conventional theory.

The pair of grad students explained the phenomenon via the quantum mechanics concept of electron momentum.  Traditional lasers are produced by electrons in equilibrium, where most have a high energy and almost zero momentum.  The new laser results from non-equilibrium, lower-energy electrons with more momentum.  Explains Franz, "It showed, contrary to what was believed, that electrons are useful for laser emission even when they are in highly non-equilibrium states."

In traditional lasers the low momentum of lasing electrons causes a large amount of photons to be reabsorbed, decreasing efficiency.  The new laser cuts this phenomenon by 90 percent, allowing the possibility of a low current laser.  It also improves performance by increasing its emissions strength with higher temperatures.

Quantum cascade lasers emit in the mid- and far-infrared range, unlike visible light lasers.  These IR beams are perfect for chemical detection.

Additional research is now being performed into how to isolate and optimize the new kind of laser, and how to perhaps extend it to visible light lasers.

The research is funded by the National Science Foundation and reported in the journal Nature Photonics.

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Who cares about BlueRay or Gaming Consoles??
By Bored SysAdmin on 12/23/2008 2:58:56 PM , Rating: 5
Guys, This laser is almost 90% more efficient than regular lasers. Say hello to much cheaper very long distance fiber links, Low-Powered optical drives and may I dream - Portable laser guns :)

Jokes aside, you know, government will keep an eye or two on this...

RE: Who cares about BlueRay or Gaming Consoles??
By lennylim on 12/23/2008 4:12:02 PM , Rating: 2
I have to say the thought of optical drives didn't even enter my mind. I don't have the figures, but I assume it takes way more energy to spin the disc than to power the laser of an optical drive. Unless, that is, you're building one of those "this disc will self destruct in 5 seconds" kind of device...

By vulcanproject on 12/23/2008 5:01:30 PM , Rating: 5
my death ray is nearing completion with this excellent...

RE: Who cares about BlueRay or Gaming Consoles??
By Whedonic on 12/23/2008 7:10:14 PM , Rating: 3
Now all I need is some Wonderflonium.

RE: Who cares about BlueRay or Gaming Consoles??
By ikkeman2 on 12/24/2008 2:07:18 AM , Rating: 3
where did you find the nescecary amounts of unobtabium

By codeThug on 12/24/2008 9:52:20 PM , Rating: 1
Upsidasium is much more efficient AND lighter.

By MrPoletski on 12/24/2008 4:33:43 AM , Rating: 2
Well this tech belongs to the university at I guess.. but which one? perhaps both, sounds like an exchange situation, one guy from the UK one from the states. Well it's nice to have a technology situation where uk vs us is moot for once hehe.

A lot of money could be made from this tech. That's a REAL small laser, what are the chances of it being integrated onto an IC? so you get a fibre link off of the chip itself, comes out on a special leg/pad. That's where this will be most awesome IMO.

RE: Who cares about BlueRay or Gaming Consoles??
By shachar2 on 12/25/2008 5:09:18 AM , Rating: 2
hold on body
do you have a license for that laser gun?

By Ammohunt on 12/29/2008 2:58:08 PM , Rating: 2
Imagine a Sniper with a man portable laser you could core a hole in someone from miles away assuming you could aim it correctly.

The Real Question is:
By michal1980 on 12/23/2008 8:01:14 PM , Rating: 5
Can we put these on sharks?

RE: The Real Question is:
By vulcanproject on 12/23/2008 8:14:17 PM , Rating: 5
Can we put these on sharks?

no. only ill tempered mutated sea bass

RE: The Real Question is:
By cubeless on 12/23/2008 8:15:53 PM , Rating: 2
these are small and low power enough to make them feasible to use on the mutant bass... now that's progress...

From the second photo caption.
By eetnoyer on 12/23/2008 4:06:27 PM , Rating: 4
"... like the one showed here..."


RE: From the second photo caption.
By lennylim on 12/23/2008 4:14:18 PM , Rating: 2
Most of what we're looking at seems like power leads and (maybe) heat sink. The laser is probably the stuff etched on the surface. I know what you mean - my first thought was "what nanoscale".

RE: From the second photo caption.
By MadMan007 on 12/23/2008 4:32:19 PM , Rating: 2
Relevant quote from the article:
It is one-tenth as thick as a human hair and 3 millimeters long and consists of atom-thick layers of different semiconductors.

3 millimeters long is obviously visible. The laser emitter is the purplish part in the middle.

By Screwballl on 12/23/2008 2:36:09 PM , Rating: 1
Sorry BluRay, we hardly knew ye...

RE: sorry
By luigi1111 on 12/24/2008 3:06:48 AM , Rating: 2
What exactly was so wrong with this post?? ... Man Dailytech's rating system has really decreased in useability...

RE: sorry
By icanhascpu on 12/24/2008 4:17:09 AM , Rating: 1
My guess is that humor should be funny? Unless he was serious then it's was even more stupid a post.

RE: sorry
By Screwballl on 12/24/2008 7:12:30 PM , Rating: 3
just a bit of dry sarcasm about how swift analog and digital formats can change... CD, DVD, HD-DVD, BluRay and so on...

By Mitch101 on 12/23/2008 6:18:21 PM , Rating: 2
50,000,000 DPI mice here we come!!!

RE: WooHoo!
By bobny1 on 12/23/2008 7:35:51 PM , Rating: 2
Wow!. More accurate 3d-tatoos that don't hurt. Cooool!!.

RE: WooHoo!
By MrPoletski on 12/24/2008 4:36:13 AM , Rating: 2
dude, you'd touch your mouse and fly off the map!

shorter wavelength?
By VultureTX on 12/24/2008 1:44:59 PM , Rating: 2
from the DT article
"The second beam on the quantum cascade lasers was identified due to its shorter wavelength than the main beam."

Yet the second beam was deep to mid IR, so the main laser beam had to be deep IR. While useful for many research and industrial apps, such a long wavelength is not efficient for data storage or even laser pointers. Blu-Ray uses the other end of the light spectrum and has greater density because the wavelength is 400nm vs IR(850+nM)

Is there some indication this might be applied to Blue or UV lasing?

RE: shorter wavelength?
By BigPeen on 12/24/2008 4:08:18 PM , Rating: 2
Probably not, there are a lot of big issues with Blue/UV GaN lasers before we start thinking about this kind of technology.

RE: shorter wavelength?
By BigPeen on 12/24/2008 4:16:53 PM , Rating: 2
From my understanding, quantum cascade lasers are generally used to INCREASE the wavelength, not decrease it. Usually it focuses on taking InP or GaAs based devices and moving them to like the 2-3um range. I don't think anyone has tried to do inverse, or if it's even possible in principle.

If it doesn't say...
By HmmSureYNot on 12/23/2008 2:40:49 PM , Rating: 2
Blueray, PS3 or XBOX 360 - This story wont get many responses. O never mind, you posted a blue-ray comment already!

RE: If it doesn't say...
By Jellodyne on 12/26/2008 10:47:43 AM , Rating: 2
Also, this new laser proves global warming is a myth.

arms race
By shachar2 on 12/25/2008 5:10:38 AM , Rating: 2
screw the economy
who's up to invest billions of $ to quickly weapanize this technology BEFORE the u.s does?

Huge IF
By Shadowself on 12/29/2008 9:51:43 AM , Rating: 2
Kale Franz describes, "This discovery provides a new insight into the physics of lasers. If we can turn off the conventional beam, we will end up with a better laser, which makes more efficient use of electrical power."

So as of right now the system is powering two separate LASER outputs. One has conventional efficiency and the other has a much higher efficiency. So at the moment the system takes more power than even a conventional LASER does.

That's a huge IF in that statement above. I certainly hope they can do it without killing the increased efficiency of the cascade beam. We'll just have to wait and see.

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