Featured Research

from universities, journals, and other organizations

Innovative Composite Opens Terahertz Frequencies To Many Applications

Date:
April 16, 2008
Source:
Boston College
Summary:
A frequency-agile meta-material that for the first time can be tuned over a range of frequencies in the so-called "terahertz gap" has been engineered. The team's first-generation device achieved 20 percent tuning of the terahertz resonance to lower frequencies -- those in the far-infrared region -- addressing the critical issue of narrow band response typical of all metamaterial designs to date.

Scanning electron microscopy (SEM) images of the frequency-tunable planar metamaterial. An individual unit cell (a. above), and periodically patterned square array (b. below). All dimensions are shown in microns and materials are indicated in the images. The polarization of the incident linearly-polarized THz radiation is also indicated in b.
Credit: Image courtesy of Nature Photonics

A frequency-agile metamaterial that for the first time can be tuned over a range of frequencies in the so-called "terahertz gap" has been engineered by a team of researchers from Boston College, Los Alamos National Laboratory and Boston University.

The team incorporated semiconducting materials in critical regions of tiny elements -- in this case metallic split-ring resonators -- that interact with light in order to tune metamaterials beyond their fixed point on the electromagnetic spectrum, an advance that opens these novel devices to a broader array of uses, according to findings published in the online version of the journal Nature Photonics.

"Metamaterials no longer need to be constructed only out of metallic components," said Boston College Physicist Willie J. Padilla, the project leader. "What we've shown is that one can take the exotic properties of metamaterials and combine them with the unique prosperities of natural materials to form a hybrid that yields superior performance."

Padilla and BC graduate student David Shrekenhamer, along with Hou-Tong Chen, John F. O'Hara, Abul K Azad and Antoinette J. Tayler of Los Alamos National Laboratory, and Boston University's Richard D. Averitt formed a single layer of metamaterial and semiconductor that allowed the team to tune terahertz resonance across a range of frequencies in the far-infrared spectrum.

The team's first-generation device achieved 20 percent tuning of the terahertz resonance to lower frequencies -- those in the far-infrared region --addressing the critical issue of narrow band response typical of all metamaterial designs to date.

Constructed on the micron-scale, metamaterials are composites that use unique metallic contours in order to produce responses to light waves, giving each metamaterial its own unique properties beyond the elements of the actual materials in use.

Within the past decade, researchers have sought ways to significantly expand the range of material responses to waves of electromagnetic radiation -- classified by increasing frequency as radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. Numerous novel effects have been demonstrated that defy accepted principles.

"Metamaterials demonstrated negative refractive index and up until that point the commonly held belief was that only a positive index was possible," said Padilla. "Metamaterials gave us access to new regimes of electromagnetic response that you could not get from normal materials."

Prior research has shown that because they rely on light-driven resonance, metamaterials experience frequency dispersion and narrow bandwidth operation where the centre frequency is fixed based on the geometry and dimensions of the elements comprising the metamaterial composite. The team believes that the creation of a material that addresses the narrow bandwidth limitations can advance the use of metamaterials.

Enormous efforts have focused on the search for materials that could respond to terahertz radiation, a scientific quest to find the building blocks for devices that could take advantage of the frequency for imaging and other applications.

Potential applications could lie in medical imaging or security screening, said Padilla. Materials undetectable through x-ray scans -- such as chemicals, biological agents, and certain explosives -- can provide a unique "fingerprint" when struck by radiation in the far-infrared spectrum. Metamaterials like the one developed by the research team will facilitate future devices operating at the terahertz frequency of the electromagnetic spectrum.

In addition to imaging and screening, researchers and high-tech companies are probing the use of terahertz in switches, modulators, lenses, detectors, high bit-rate communications, secure communications, the detection of chemical and biological agents and characterization of explosives, according to Los Alamos National Laboratory.


Story Source:

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


Cite This Page:

Boston College. "Innovative Composite Opens Terahertz Frequencies To Many Applications." ScienceDaily. ScienceDaily, 16 April 2008. <www.sciencedaily.com/releases/2008/04/080415185016.htm>.
Boston College. (2008, April 16). Innovative Composite Opens Terahertz Frequencies To Many Applications. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2008/04/080415185016.htm
Boston College. "Innovative Composite Opens Terahertz Frequencies To Many Applications." ScienceDaily. www.sciencedaily.com/releases/2008/04/080415185016.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) 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