Featured Research

from universities, journals, and other organizations

Lasers And Milk: The Common Denominator

Date:
May 5, 2008
Source:
ETH Zurich
Summary:
Reading about a "random laser" for the first time, you might wonder whether this term refers to the laser in your CD player which plays the song titles in the random shuffle mode. In physics, however, "random lasers" refer to a class of microlasers which use the principle of random light scattering as an integral part of the laser operation. In conventional lasers light is trapped between two highly reflecting mirrors where it is amplified by pumping from outside. Only when this amplification process is efficient enough, the laser begins to operate.

Reading about a "random laser" for the first time, you might wonder whether this term refers to the laser in your CD player which plays the song titles in the random shuffle mode. In physics, however, "random lasers" refer to a class of microlasers which use the principle of random light scattering as an integral part of the laser operation.

In conventional lasers light is trapped between two highly reflecting mirrors where it is amplified by pumping from outside. Only when this amplification process is efficient enough, the laser begins to operate. After the initiation of the modern study of random lasers by Nabil M. Lawandy (Brown University), it was demonstrated by Hui Cao (Northwestern/Yale) and coworkers that you don't necessarily require elaborate mirrors to confine light long enough for lasing from micron sized devices.

Related Articles


All you need to do is to put light into a highly disordered medium where scattering in random directions takes place. This mechanism, similar to the multiple scattering of light which makes a glass of milk look white, can prevent the light from escaping too quickly. If the random medium is optically active, pumping it with energy from outside will result in the emission of coherent light at sharply defined frequencies and in random directions.

"In pratice, random lasers are small beads of micrometer size, too small to be seen by the human eye", says Hakan E. Tόreci, a research associate in the Quantum Photonics Group at ETH Zurich, who coauthored the article with Li Ge, Stefan Rotter and A. Douglas Stone at Yale University. "Due to their robustness and ease of manufacture, these lasers are sometimes referred to as "laser paint" and have found various applications, currently commercially available, such as document security and remote sensing. There are envisioned application areas in diagnostic imaging and super-fast displays as well".

Laser theory extended

Conventional laser theory tries to describe the operation of a laser by looking at the resonances of the laser cavity. In a random laser these resonances are, due to the lack of any defining mirrors, however, not at all well defined. The resonances are so closely spaced that they cannot be looked at independently of each other. Tόreci and co-workers at Yale University have now extended the conventional laser theory such that it can be applied to random lasers, one of the most exotic type of lasers in existence, as well. In recent experiments it was observed that a specific random laser always shines at the same frequencies, but at intensities which differ strongly from measurement to measurement. With their publication in Science the authors show that this result can be traced back to unusually strong interactions between the laser modes.

Tόreci said, "Future research in designing novel micro and nanolasers will benefit from our approach, and we are implementing some of these ideas already with experimental collaborators to improve, e.g. power output, directional emission, for different kinds of microlasers."


Story Source:

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


Cite This Page:

ETH Zurich. "Lasers And Milk: The Common Denominator." ScienceDaily. ScienceDaily, 5 May 2008. <www.sciencedaily.com/releases/2008/05/080502110829.htm>.
ETH Zurich. (2008, May 5). Lasers And Milk: The Common Denominator. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2008/05/080502110829.htm
ETH Zurich. "Lasers And Milk: The Common Denominator." ScienceDaily. www.sciencedaily.com/releases/2008/05/080502110829.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) — A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) — Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) — What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) — US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
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