Featured Research

from universities, journals, and other organizations

Quantum dots provide complete control of photons

Date:
January 31, 2014
Source:
Linköping University
Summary:
By emitting photons from a quantum dot at the top of a micropyramid, researchers are creating a polarized light source for such things as energy-saving computer screens and wiretap-proof communications.

Scientists are creating a polarized light source for such things as energy-saving computer screens and wiretap-proof communications.
Credit: Image courtesy of Linköping University

By emitting photons from a quantum dot at the top of a micropyramid, researchers at Linköping University are creating a polarized light source for such things as energy-saving computer screens and wiretap-proof communications.

Polarized light -- where all the light waves oscillate on the same plane -- forms the foundation for technology such as LCD displays in computers and TV sets, and advanced quantum encryption. Normally, this is created by normal unpolarized light passing through a filter that blocks the unwanted light waves. At least half of the light emitted, and thereby an equal amount of energy, is lost in the process.

A better method is to emit light that is polarized right at the source. This can be achieved with quantum dots -- crystals of semiconductive material so small that they produce quantum mechanical phenomena. But until now, they have only achieved polarization that is either entirely too weak or hard to control.

A semiconductive materials research group led by Professor Per Olof Holtz is now presenting an alternative method where asymmetrical quantum dots of a nitride material with indium is formed at the top of microscopic six-sided pyramids. With these, they have succeeded in creating light with a high degree of linear polarization, on average 84%. The results are being published in the Nature periodical Light: Science & Applications.

"We're demonstrating a new way to generate polarized light directly, with a predetermined polarization vector and with a degree of polarization substantially higher than with the methods previously launched," Professor Holtz says.

In experiments, quantum dots were used that emit violet light with a wavelength of 415 nm, but the photons can in principle take on any colour at all within the visible spectrum through varying the amount of the metal indium.

"Our theoretical calculations point to the fact that an increased amount of indium in the quantum dots further improves the degree of polarization," says reader Fredrik Karlsson, one of the authors of the article.

The micropyramid is constructed through crystalline growth, atom layer by atom layer, of the semiconductive material gallium nitride. A couple of nanothin layers where the metal indium is also included are laid on top of this. From the asymmetrical quantum dot thus formed at the top, light particles are emitted with a well-defined wavelength.

The results of the research are opening up possibilities, for example for more energy-effective polarized light-emitting diodes in the light source for LCD screens. As the quantum dots can also emit one photon at a time, this is very promising technology for quantum encryption, a growing technology for wiretap-proof communications.


Story Source:

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


Journal Reference:

  1. Anders Lundskog, Chih-Wei Hsu, K Fredrik Karlsson, Supaluck Amloy, Daniel Nilsson, Urban Forsberg, Per Olof Holtz, Erik Janzén. Direct generation of linearly polarized photon emission with designated orientations from site-controlled InGaN quantum dots. Light: Science & Applications, 2014; 3 (1): e139 DOI: 10.1038/lsa.2014.20

Cite This Page:

Linköping University. "Quantum dots provide complete control of photons." ScienceDaily. ScienceDaily, 31 January 2014. <www.sciencedaily.com/releases/2014/01/140131101203.htm>.
Linköping University. (2014, January 31). Quantum dots provide complete control of photons. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2014/01/140131101203.htm
Linköping University. "Quantum dots provide complete control of photons." ScienceDaily. www.sciencedaily.com/releases/2014/01/140131101203.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) — A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Stranded Whale Watching Boat Returns to Boston

Stranded Whale Watching Boat Returns to Boston

Reuters - US Online Video (July 29, 2014) — Passengers stuck overnight on a whale watching boat return safely to Boston. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) — Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) — The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
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