Featured Research

from universities, journals, and other organizations

Harnessing randomness to improve lasers

Date:
January 18, 2014
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
The first electrically pumped random lasers for mid-infrared radiation are set to enable applications in sensing and imaging.

Computed optical light fields in a random laser overlaid on black circles, which represent the nanoholes drilled into a semiconductor quantum cascade laser, to produce a laser pattern with low spatial coherence.
Credit: 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Developed at A*STAR, the first electrically pumped random lasers for mid-infrared radiation are set to enable applications in sensing and imaging

Related Articles


Randomly arranged items usually have poor optical properties. The rough -- or random -- surface of a frosted-glass window, for example, obscures the view of an object. The optical industry therefore expends considerable effort reducing any surface irregularities in optical devices to avoid the uncontrollable scattering of light characteristic of random structures.

But now, a research group led by Ying Zhang from the A*STAR Singapore Institute of Manufacturing Technology (SIMTech) has made good use of randomness by studying how random structures can improve the performance of lasers. Together with a team led by Qijie Wang at Nanyang Technical University in Singapore, the group has demonstrated the world's first electrically pumped mid-infrared random laser, which operates at a 10-micrometer wavelength. The laser is as bright as conventional diode lasers but produces less-speckled images.

Light waves from a conventional laser oscillate in perfect synchronicity, across both time and space. Perfect alignment of the light waves at different time and different locations across the beam profile is known as temporal and spatial coherence, respectively. When a laser illuminates a surface, a speckled pattern is typically visible, which indicates spatial coherence. The speckles result from the laser beam reflecting from different parts of the surface. Because the waves are in sync, they create spatial interference effects in the eye of an observer. This distortion is undesirable, particularly in biomedical imaging applications conducted in the infrared region of the spectrum.

Random lasers are the solution to this type of distortion, says Zhang. "Random lasers show the same high temporal coherence as that of other lasers but have a lower spatial coherence," he explains. "High temporal coherence gives the desirable brightness but it is the low spatial coherence that removes the speckles caused by interferences."

To realize a random laser in the mid-infrared spectrum, Zhang and co-workers used a semiconductor quantum cascade laser into which they had drilled a random pattern of nanoholes. At a sufficiently high density, these holes prevent the formation of a regular laser pattern within the semiconductor (see image). Instead, the pattern of a random laser forms, with low spatial coherence.

Employing a quantum cascade laser to realize the random lasers allows for the polarization of the laser light perpendicular to the laser surface. This propagation minimizes losses owing to the air-hole structure.

The research team's wafer-fabrication competencies enabled them to drill holes deep enough into the laser chip, with sufficiently smooth side walls to minimize losses in the laser itself. By introducing these perfections and overcoming a number of other practical hurdles, Zhang and his colleagues succeeded in making the lasers efficient enough to provide lasing during electrical operation.

Nevertheless, notes Hou Kun Liang of SIMTech, who invented the mid-infrared random laser, more work is needed to bring random lasers to market. "We are working on a random laser that operates at room temperature. And in the long-term, we plan to extend random lasers from the infrared to even longer wavelengths and can be used for inspection of various polymer packaging quality-control of printed electronics, biomedical imaging, among other applications."

The A*STAR Singapore Institute of Manufacturing Technology (SIMTech) develops high-value manufacturing technology and human capital to contribute to the competitiveness of Singapore's industry. It collaborates with universities as well as multinational and local companies in the precision engineering, electronics, semiconductor, medical technology, aerospace, automotive, marine, logistics and other sectors.


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Hou Kun Liang, Bo Meng, Guozhen Liang, Jin Tao, Yidong Chong, Qi Jie Wang, Ying Zhang. Electrically Pumped Mid-Infrared Random Lasers. Advanced Materials, 2013; 25 (47): 6859 DOI: 10.1002/adma.201303122

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Harnessing randomness to improve lasers." ScienceDaily. ScienceDaily, 18 January 2014. <www.sciencedaily.com/releases/2014/01/140118122413.htm>.
The Agency for Science, Technology and Research (A*STAR). (2014, January 18). Harnessing randomness to improve lasers. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2014/01/140118122413.htm
The Agency for Science, Technology and Research (A*STAR). "Harnessing randomness to improve lasers." ScienceDaily. www.sciencedaily.com/releases/2014/01/140118122413.htm (accessed October 24, 2014).

Share This



More Matter & Energy News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Police Testing New Gunfire Tracking Technology

Police Testing New Gunfire Tracking Technology

AP (Oct. 24, 2014) A California-based startup has designed new law enforcement technology that aims to automatically alert dispatch when an officer's gun is unholstered and fired. Two law enforcement agencies are currently testing the technology. (Oct. 24) Video provided by AP
Powered by NewsLook.com
3D Printed Instruments Make Sweet Music in Sweden

3D Printed Instruments Make Sweet Music in Sweden

Reuters - Innovations Video Online (Oct. 23, 2014) Students from Lund University's Malmo Academy of Music are believed to be the world's first band to all use 3D printed instruments. The guitar, bass guitar, keyboard and drums were built by Olaf Diegel, professor of product development, who says 3D printing allows musicians to design an instrument to their exact specifications. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
NYPD Gives High Tech Anti-Terror Weapon to 41,000 Officers

NYPD Gives High Tech Anti-Terror Weapon to 41,000 Officers

Buzz60 (Oct. 23, 2014) New York City officials announce a new technology initiative for the NYPD. Tim Minton reports smartphones and tablets will be given to more than 40,000 NYPD officers and detectives in an effort to change the way they perform their duties. Video provided by Buzz60
Powered by NewsLook.com
Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
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