Featured Research

from universities, journals, and other organizations

Powering lasers through heat

Date:
November 13, 2012
Source:
University of Innsbruck
Summary:
In micro electronics heat often causes problems and engineers have to put a lot of technical effort into cooling, for example micro chips, to dissipate heat that is generated during operation. Physicists have now suggested a concept for a laser that could be powered by heat. This idea may open a completely new way for cooling microchips.

Schematic picture of a quantum cascade laser. The layers of different semiconductor material constitute the bandstructure shown in the inset.
Credit: Graphics: Christoph Deutsch

In micro electronics heat often causes problems and engineers have to put a lot of technical effort into cooling, for example micro chips, to dissipate heat that is generated during operation. Innsbruck physicists have now suggested a concept for a laser that could be powered by heat. This idea may open a completely new way for cooling microchips.

Related Articles


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, 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.


Story Source:

The above story is based on materials provided by University of Innsbruck. Note: Materials may be edited for content and length.


Journal Reference:

  1. K. Sandner, H. Ritsch. Temperature Gradient Driven Lasing and Stimulated Cooling. Physical Review Letters, 2012; 109 (19) DOI: 10.1103/PhysRevLett.109.193601

Cite This Page:

University of Innsbruck. "Powering lasers through heat." ScienceDaily. ScienceDaily, 13 November 2012. <www.sciencedaily.com/releases/2012/11/121113083534.htm>.
University of Innsbruck. (2012, November 13). Powering lasers through heat. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2012/11/121113083534.htm
University of Innsbruck. "Powering lasers through heat." ScienceDaily. www.sciencedaily.com/releases/2012/11/121113083534.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins