Featured Research

from universities, journals, and other organizations

New quantum mechanism to trigger the emission of tunable light at terahertz frequencies

Date:
June 18, 2014
Source:
University of Southampton
Summary:
Scientists have found that two-dimensional (2-D) nanostructures with asymmetric design enable a new quantum mechanism, triggering the emission of tunable light at terahertz frequencies-with unprecedented efficiency. The researchers found that quantum wells, 2-D nanostructures formed of several layers of semi-conductor alloys placed on top of each other like a sandwich, can enhance light emission in a technological challenging spectral range.

An optoelectronic device formed of multiple quantum wells, whose design is optimised to maximise the dipole and thus its efficiency, emitting terahertz light.
Credit: Image courtesy of University of Southampton

Scientists have found that two-dimensional (2D) nanostructures with asymmetric design enable a new quantum mechanism, triggering the emission of tuneable light at terahertz frequencies-with unprecedented efficiency.

The researchers, from the University of Southampton and Imperial College London, found that quantum wells, 2D nanostructures formed of several layers of semi-conductor alloys placed on top of each other like a sandwich, can enhance light emission in a technological challenging spectral range.

It is hoped that the findings will have an impact on photonic and optoelectronic devices across a broad range of applications, including harmless medical imaging and security scanning.

Electrons are trapped in the structure and this confinement can be exploited to enhance their capacity to interact with light at given frequencies much lower than the laser frequency at which they are excited: the system emits light by interacting with "vacuum fluctuations" that permeate space, according to quantum theory.

Nathan Shammah, from the University's Quantum Light and Matter (QLM) group and co-author of the study says: "As the 2D nanostructures can be manufactured with an asymmetric design, this allows light to interact with trapped electrons in a way that is not otherwise allowed. This interaction process, leading to the emission of light at lower frequencies, has not been observed in atoms because those are very symmetrical systems and symmetry rules prevent the transitions that trigger this light emission from happening."

In the paper, which is published in Physical Review B, the researchers predict that by shining light on a 2D asymmetric nanostructure with a laser that is tuned at resonance with the electronic transitions that can occur in the nanostructure, in addition to the scattered laser light, this 2D device would emit light at other frequencies, which can be tuned simply by changing the laser power.

Nathan, who co-authored the paper with Dr Simone De Liberato, from the QLM group, and Professor Chris Phillips from Imperial College London, adds: "Due to the large oscillating dipole and high density of electrons that characterise these 'artificial atoms' formed of asymmetric 2D structures, the control of light-matter coupling can be greatly enhanced, triggering spontaneous light emission, similar to what occurs in LEDs lamps.

"This new mechanism is perfectly suited for the terahertz frequency range, which spans from above the current wi-fi bandwidth to below the visible light spectrum, where the lack of practical light emitters constitutes a serious technological gap."

The high efficiency shown by the simulations suggests that this theoretical result could be exploited in the near future for a broad range of optoelectronic applications-from harmless medical imaging and security scanners, to short-range, ultra-fast wireless communication.


Story Source:

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


Journal Reference:

  1. Nathan Shammah, Chris C. Phillips, Simone De Liberato. Terahertz emission from ac Stark-split asymmetric intersubband transitions. Physical Review B, 2014; 89 (23) DOI: 10.1103/PhysRevB.89.235309

Cite This Page:

University of Southampton. "New quantum mechanism to trigger the emission of tunable light at terahertz frequencies." ScienceDaily. ScienceDaily, 18 June 2014. <www.sciencedaily.com/releases/2014/06/140618100530.htm>.
University of Southampton. (2014, June 18). New quantum mechanism to trigger the emission of tunable light at terahertz frequencies. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2014/06/140618100530.htm
University of Southampton. "New quantum mechanism to trigger the emission of tunable light at terahertz frequencies." ScienceDaily. www.sciencedaily.com/releases/2014/06/140618100530.htm (accessed August 29, 2014).

Share This




More Matter & Energy News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. 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:
from the past week

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