(Press-News.org) This press release is available in German.
Since its invention 50 years ago, laser light has conquered our daily life. Lasers of varying wave lengths and power are used in many parts of our life, from consumer electronics to telecommunication and medicine. However, not all wave lengths have been equally well researched. For the far infrared and terahertz regime quantum cascade lasers are the most important source of coherent radiation. Light amplification in such a cascade laser is achieved through a repeated pattern of specifically designed semi-conductor layers of diverse doping through which electric current is running. "The electrons are transferred through this structure in a specific series of tunneling processes and quantum leaps, emitting coherent light particles," explains Helmut Ritsch, Institute for Theoretical Physics, University of Innsbruck in Austria, the functioning of such a laser. "Between these layers the electrons collide with other particles, which heats the laser." Thus, quantum cascade lasers only work as long as they are strongly cooled. When too much heat is produced, the laser light extinguishes.
Revolutionary concept
When looking for ways to reduce heat in lasers, PhD student Kathrin Sandner and Helmut Ritsch came up with a revolutionary idea: The theoretical physicists suggest using heat to power the laser. In their work, recently published in Physical Review Letters, the two physicists propose the theory that the heating effect in quantum cascade lasers could not only be avoided but, in fact, reversed through a cleverly-devised modification of the thickness of the semiconductor layers. "A crucial part is to spatially separate the cold and warm areas in the laser," explains Kathrin Sandner. "In such a temperature gradient driven laser, electrons are thermally excited in the warm area and then tunnel into the cooler area where photons are emitted." This produces a circuit where light particles are emitted and heat is absorbed from the system simultaneously. "Between the consecutive emissions of light particles a phonon is absorbed and the laser is cooled. When we develop this idea further, we see that the presence of phonons may be sufficient to provide the energy for laser amplification," says Kathrin Sandner. Such a laser could be powered without using electric current.
"Of course, it is quite a challenge to implement this concept in an experiment," says Helmut Ritsch. "But if we are successful, it will be a real technological innovation." The physical principle behind the idea could already be applied to existing quantum cascade lasers, where it could provide internal cooling. This simplified concept seems to be technically feasible and is already being examined by experimental physicists.
Elegant idea with technical potential
"Apart from the conceptual elegance of this idea, a completely new way may open up of using heat in microchips in a beneficial way instead of having to dissipate it by cooling," says an excited Helmut Ritsch about the work of his student. Kathrin Sandner majored in physics in Freiburg, Germany, and has worked as a researcher at the Institute for Theoretical Physics, University of Innsbruck, since 2009. "If you want to do research in quantum optics, Innsbruck is the place to go," says Sandner about her motivation to work in Innsbruck. Kathrin Sandner was supported by the DOC-fFORTE doctoral program of the Austrian Academy of Sciences and by a PhD grant from the University of Innsbruck. She is about to finish her PhD program.
INFORMATION:
Powering lasers through heat
2012-11-13
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
Sperm length variation is not a good sign for fertility
2012-11-13
PROVIDENCE, R.I. [Brown University] — Perhaps variety is the very spice of life, but as a matter of producing human life, it could be the bane of existence. That's the indication of a new study in the journal Human Reproduction that found men with wider variation in sperm length, particularly in the flagellum, had lower concentrations of sperm that could swim well. Those with more consistently made sperm seemed to have more capable ones.
"Our study reveals that men who produce higher concentrations of competent swimming sperm also demonstrate less variation in the size ...
Computer memory could increase fivefold from advances in self-assembling polymers
2012-11-13
AUSTIN, Texas — The storage capacity of hard disk drives could increase by a factor of five thanks to processes developed by chemists and engineers at The University of Texas at Austin.
The researchers' technique, which relies on self-organizing substances known as block copolymers, was described this week in an article in Science. It's also being given a real-world test run in collaboration with HGST, one of the world's leading innovators in disk drives.
"In the last few decades there's been a steady, exponential increase in the amount of information that can be stored ...
Human eye gives researchers visionary design for new, more natural lens technology
2012-11-13
WASHINGTON, Nov. 13—Drawing heavily upon nature for inspiration, a team of researchers has created a new artificial lens that is nearly identical to the natural lens of the human eye. This innovative lens, which is made up of thousands of nanoscale polymer layers, may one day provide a more natural performance in implantable lenses to replace damaged or diseased human eye lenses, as well as consumer vision products; it also may lead to superior ground and aerial surveillance technology.
This work, which the Case Western Reserve University, Rose-Hulman Institute of Technology, ...
Doubling down against diabetes
2012-11-13
This press release is available in German.
A collaboration between scientists in Munich, Germany and Bloomington, USA may have overcome one of the major challenges drug makers have struggled with for years: Delivering powerful nuclear hormones to specific tissues, while keeping them away from others.
The teams led by physician Matthias Tschöp (Helmholtz Zentrum München, and Technische Universität München) and chemist Richard DiMarchi (Indiana University) used natural gut peptides targeting cell membrane receptors and engineered them to carry small steroids known to ...
New study examines how health affects happiness
2012-11-13
Fairfax, Va., (November 13, 2012) — A new study published in the Journal of Happiness Studies found that the degree to which a disease disrupts daily functioning is associated with reduced happiness.
Lead author Erik Angner, associate professor of philosophy, economics and public policy at George Mason University, worked with an interdisciplinary team of researchers from the University of Alabama at Birmingham, the University of Chicago and the University of Massachusetts Medical School. The full study is available at http://www.springerlink.com/content/k5231631755g86g2/?MUD=MP.
Previous ...
Advocacy for planned home birth not in patients' best interest
2012-11-13
Philadelphia, PA, November 13, 2012 – Advocates of planned home birth have emphasized its benefits for patient safety, patient satisfaction, cost effectiveness, and respect for women's rights. A clinical opinion paper published in the American Journal of Obstetrics and Gynecology critically evaluates each of these claims in its effort to identify professionally appropriate responses of obstetricians and other concerned physicians to planned home birth.
Throughout the United States and Europe, planned home birth has seen increased activity in recent years. Professional ...
Study sheds light on genetic 'clock' in embryonic cells
2012-11-13
As they develop, vertebrate embryos form vertebrae in a sequential, time-controlled way. Scientists have determined previously that this process of body segmentation is controlled by a kind of "clock," regulated by the oscillating activity of certain genes within embryonic cells. But questions remain about how precisely this timing system works.
A new international cross-disciplinary collaboration between physicists and molecular genetics researchers advances scientists' understanding of this crucial biological timing system. The study, co-authored by McGill University ...
Underemployment persists since recession, with youngest workers hardest hit
2012-11-13
DURHAM, N.H. – Underemployment has remained persistently high in the aftermath of the Great Recession with workers younger than 30 especially feeling the pinch, according to new research from the Carsey Institute at the University of New Hampshire.
"While on the decline, these rates have yet to return to their prerecession levels. Moreover, as the recession and other economic forces keeps older workers in the economy, openings for full-time jobs for younger workers might remain limited in the short-term," said Justin Young, a doctoral student in sociology at UNH and a ...
Edison Pharmaceuticals announces initiation of EPI-743 Phase 2B Leigh Syndrome Clinical Trial
2012-11-13
Mountain View, California; November 13, 2012. Edison Pharmaceuticals today announced the initiation of a phase 2B study entitled, "A Phase 2B Randomized, Placebo-Controlled, Double-Blind Clinical Trial of EPI-743 in Children with Leigh Syndrome." Four clinical trial sites have been selected in the United States: Lucile Packard Children's Hospital, Stanford University Medical Center – Palo Alto, California; Akron Children's Hospital – Akron, Ohio; Seattle Children's Hospital – Seattle, Washington; and Texas Children's Hospital, Baylor University – Houston, Texas.
The ...
A sip of resveratrol and a full p53: Ingredients for a successful cell death
2012-11-13
Rio de Janeiro, Brazil- Resveratrol is a naturally occurring dietary compound found in grapes, berries, and peanuts. This polyphenol protects plants against pathogens such as bacteria and fungi by inducing cell death in invading organisms. The compound was discovered in red wine in 1939 but by large did not attract the attention of the scientific community. More recently, pre-clinical studies have revealed the many beneficial properties of resveratrol. These include antidiabetic, cardioprotective, and chemopreventive effects. The latter has been associated to resveratrol ...