Featured Research

from universities, journals, and other organizations

Tunable terahertz wire laser

Date:
May 13, 2010
Source:
Optical Society of America
Summary:
Terahertz (THz) radiation is one of the hottest areas of modern physics research. This is because THz light waves, or T-rays as they are sometimes called, have great potential for spectroscopy and for the scanning of objects in a homeland security setting that are opaque to infrared and visible light. Now scientists have combined several technologies to obtain a versatile source of THz light.

Terahertz (THz) radiation is one of the hottest areas of modern physics research. This is because THz light waves, or T-rays as they are sometimes called, have great potential for spectroscopy and for the scanning of objects in a homeland security setting that are opaque to infrared and visible light.

Related Articles


The trouble is that THz light waves -- which fall in the range of 0.3 to 10 trillion cycles per second or, equivalently, wavelengths of about 30 to 1000 microns -- are difficult to make with traditional means. Now scientists at MIT have combined several technologies to obtain a versatile source of THz light.

They start with a quantum cascade laser (QCL) device, which differs fundamentally from a traditional semiconductor laser. In most traditional lasers, light comes from the recombination of an electron with a hole (a vacancy in the surrounding semiconducting material). But in a QCL device, light comes from the transition of an electron to a succession of ever lower energy levels in a series of layers in a sandwich-style structure of thin semiconducting layers.

This type of laser has a unique property: one electron (as it moves through the layers) triggers the release of many photons. The emitted light energy of the device can be changed by altering the thickness of the layers.

Population inversion is provided over a range of energies provided by the cascaded energy levels described above with the fine energy or wavelength selection provided by the laser cavity. In the MIT approach, tuning is achieved by changing the width of the laser light beam (and hence cavity) by precisely controlling the distance between a specially designed block material and the laser. This technique is analogous to changing the pitch of a guitar string by changing its diameter. In this case, the laser waveguide is much narrower than the wavelength of the light, hence the description of this setup as a "wire" laser.

Qi Qin of MIT says their cascade laser can be tuned continuously and controllably to produce terahertz radiation over a broad range. "At present, this is the only viable mechanism to achieve broad continuous tuning in terahertz quantum-cascade lasers," says Qin.

The work is being reported at the 2010 Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference (CLEO/QELS) May 16-21 at the San Jose McEnery Convention Center in San Jose, Calif., where researchers from around the world are presenting the latest breakthroughs in electro-optics, innovative developments in laser science, and commercial applications in photonics.

Presentation: "Development of Tunable Terahertz Wire Lasers" by Qi Qin et al. is at 3 p.m. on Thursday, May 20.


Story Source:

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


Cite This Page:

Optical Society of America. "Tunable terahertz wire laser." ScienceDaily. ScienceDaily, 13 May 2010. <www.sciencedaily.com/releases/2010/05/100511143525.htm>.
Optical Society of America. (2010, May 13). Tunable terahertz wire laser. ScienceDaily. Retrieved April 21, 2015 from www.sciencedaily.com/releases/2010/05/100511143525.htm
Optical Society of America. "Tunable terahertz wire laser." ScienceDaily. www.sciencedaily.com/releases/2010/05/100511143525.htm (accessed April 21, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Tuesday, April 21, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Humanoid Robot Can Recognise and Interact With People

Humanoid Robot Can Recognise and Interact With People

Reuters - Innovations Video Online (Apr. 20, 2015) An ultra-realistic humanoid robot called &apos;Han&apos; recognises and interprets people&apos;s facial expressions and can even hold simple conversations. Developers Hanson Robotics hope androids like Han could have uses in hospitality and health care industries where face-to-face communication is vital. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Drones and Health Apps at Santiago's "Robotics Day"

Drones and Health Apps at Santiago's "Robotics Day"

AFP (Apr. 20, 2015) Latin American robotics experts gather in Santiago, Chile for "Robotics Day". Video provided by AFP
Powered by NewsLook.com
Japan Humanoid Robot Receives Customers at Department Store

Japan Humanoid Robot Receives Customers at Department Store

AFP (Apr. 20, 2015) She can smile, she can sing and she can give you guidance at one of the most upscale department stores in Tokyo...a female-looking humanoid makes her debut as a receptionist Video provided by AFP
Powered by NewsLook.com
Pee-Power Toilet to Light Up Disaster Zones

Pee-Power Toilet to Light Up Disaster Zones

Reuters - Innovations Video Online (Apr. 20, 2015) Students and staff are being asked to use a prototype urinal to &apos;donate&apos; urine to fuel microbial fuel cell (MFC) stacks that generate electricity to power lighting. The developers hope the pee-power technology will light toilet cubicles in refugee camps, where women are often at risk of assault in poorly lit sanitation areas. 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