Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Design of composite materials that detect terahertz discovered

05.03.2004


A team of physicists and engineers from the University of California, San Diego, the University of California, Los Angeles and Imperial College, London have developed a class of materials that respond magnetically to terahertz radiation, a fundamental finding relevant to many exciting applications in areas including guidance in zero visibility weather conditions, security and biomedical imaging and quality control.


Scanning electron microscope image of the metamaterial. Credit: Ta-Jen Yen UCLA



The materials described in the study to be published in the March 5th issue of the journal Science are metamaterials—artificially structured materials that extend the properties of existing naturally occurring materials and compounds. In 2000, UCSD researchers created and reported the first measurements of left-handed metamaterials —so-called because they reverse many of the physical properties that govern the behavior of ordinary materials. Left-handed materials were named one of the Top Ten scientific breakthroughs of the year by Science in December 2003 when these materials and their properties were independently confirmed by multiple groups. While not left-handed, the present metamaterials demonstrate that the magnetic response can be extended to much higher frequencies, namely the terahertz range, a set of frequencies that are intermediate between those of infrared rays and microwave rays.

“When we developed the initial left handed materials that responded in the microwave range, we were not certain if it were technically feasible to develop materials that responded to higher frequencies,” says David Smith, coauthor on the study and associate adjunct professor in UCSD’s physics department. “This is a particularly exciting advance because materials that respond in the terahertz range have many potential applications. There are very few natural materials that respond magnetically in the terahertz range.”


The material designed by the researchers consists of a two-dimensional array of repeated patterned copper elements, called split ring resonators, deposited on a quartz plate. Each split ring resonator is made up of two concentric copper squares, both having a small gap. The gap in the larger square is on the opposite side as the gap in the smaller square. The width of one of the split ring resonators is roughly 50 microns, less than the thickness of a human hair.

The copper elements that compose these materials are analogous to the atoms in a regular material. While copper on its own is not magnetic, the geometry of the resonator leads to an effective magnetic response, so that the composite metamaterial can be characterized as magnetic. Therefore, these engineered metamaterials have properties that are not observed in their constituent materials.

“Designing terahertz or optical devices and components has many challenges,” explained project leader Xiang Zhang, a professor in the UCLA Henry Samueli School of Engineering and Applied Science. “Our work provides a new foundation for materials selection and device design, and we think it has the potential to enable an entirely new array of applications.”

The original idea for left-handed composites came from Smith, building on the work of John Pendry, coauthor and professor of physics at Imperial College, London. In 1996, Pendry theorized that certain configurations of metal can have unique responses to electric and magnetic fields. The Russian theorist V.G. Veselago initially predicted, in 1968, that materials which reverse physical properties, such as the direction light bends when it passes through water, lenses and other ordinary materials, might be possible.

According to the researchers, while terahertz scanners have great potential, up until now their uses have been limited because of the lack of inexpensive methods to generate and detect terahertz rays.

“Images taken using terahertz rays have good contrast between similar density objects,” explains Willie Padilla a graduate student in the laboratory of UCSD professor of physics Dimitri Basov. Both Padilla and Basov are coauthors on the paper. “So when building aircraft, terahertz scanners could be used to image aircraft components, even if the components were of similar densities. Also, terahertz is useful for medical imaging and has the advantage that it is much less damaging than X-rays, because it consists of non-ionizing radiation,” adds Padilla.

“The Department of Defense is interested in terahertz because certain chemical and bioterror agents, like anthrax happen to have a distinct absorption in the terahertz range, and since terahertz can penetrate clothing, it is also of interest for airport screening of weapons and explosives. Terahertz rays could also help pilots guide airplanes in foggy weather because water doesn’t scatter terahertz rays at particular frequencies,” says Padilla.

The other researchers involved in this study were Ta-Jen Yen, and Nicholas Fang, both graduate students in Zhang’s laboratory and David C. Vier, an associate project scientist working with Professor Smith. The study was part of a Multidisciplinary University Research Initiative sponsored by the Defense Advanced Research Projects Agency through the Office of Naval Research and the US Army Research Office, as well as the National Science Foundation.

Sherry Seethaler | UCSD
Further information:
http://ucsdnews.ucsd.edu/newsrel/science/smetamaterial.asp

More articles from Materials Sciences:

nachricht Scientists develop low-cost energy-efficient materials
24.04.2019 | National University of Science and Technology MISIS

nachricht Modified 'white graphene' for eco-friendly energy
23.04.2019 | Tomsk Polytechnic University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Energy-saving new LED phosphor

The human eye is particularly sensitive to green, but less sensitive to blue and red. Chemists led by Hubert Huppertz at the University of Innsbruck have now developed a new red phosphor whose light is well perceived by the eye. This increases the light yield of white LEDs by around one sixth, which can significantly improve the energy efficiency of lighting systems.

Light emitting diodes or LEDs are only able to produce light of a certain colour. However, white light can be created using different colour mixing processes.

Im Focus: Quantum gas turns supersolid

Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.

Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

Proteins stand up to nerve cell regression

24.04.2019 | Life Sciences

New sensor detects rare metals used in smartphones

24.04.2019 | Life Sciences

Controlling instabilities gives closer look at chemistry from hypersonic vehicles

24.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>