Trapping T-rays for better security scanners

July 11, 2013
A concept design of the silicon-based metamaterial. Credit: Dr Daniel White, ScienceFX

( —Medical diagnostic and security scanners with higher sensitivity could result from University of Adelaide research into detecting T-rays (terahertz waves).

Published in the journal Advanced Optical Materials, the researchers describe a novel structure which traps terahertz waves in tiny (micro-scale) holes to produce much higher contrast imaging than currently possible.

Terahertz waves, which are with frequencies between those used for mobile and for optical fibre communications, are used for some airport and other security scanners to see through packages and clothes. They are also capable of distinguishing malignant from healthy tissues for cancer detection.

"This work takes an unconventional path to detecting terahertz waves," says Dr Withawat Withayachumnankul, project leader and ARC Postdoctoral Fellow in the University's School of Electrical and Electronic Engineering.

Dr Withayachumnankul has worked with RMIT University in Melbourne and Albert Ludwigs University of Freiburg in Germany to produce the new structure using metamaterials (materials that show non-natural properties with the use of carefully engineered structures).

The structure is made of tiny (micro-scale) cavities etched into the surface of silicon. Terahertz waves that hit the structure are captured and compressed inside the cavities.

"By tailoring the silicon properties through the use of micro-structures (the size of a cross-section of human hair) it is possible to trap and confine the waves in a volume much smaller than the wavelength of the terahertz ," says Dr Withayachumnankul.

"This significantly improves the efficiency of terahertz devices such as scanners and will have broad impact on biomedicine and homeland security, where better contrast means more accurate identification."

RMIT team leader Dr Sharath Sriram says: "We needed to carefully select appropriate materials and processes to produce this device. We couldn't construct the micro-cavities in our first choice of material so we changed to silicon which we had to adapt to make it slightly electrically conductive. We then used established silicon microfabrication techniques to create the micro-cavities, exploiting the conductive properties."

The new structure could be added to conventional terahertz imaging devices to enhance their performance.

Explore further: Using terahertz imaging to seek quirks in corks at NJIT

More information:

Related Stories

Using terahertz imaging to seek quirks in corks at NJIT

December 8, 2010

As the holidays approach and you're buying wine, ever wonder what's really in a cork? Ask NJIT's John Federici, who has a new use for Terahertz imaging: searching for divots and cracks in wine corks to insure quality.

Graphene may open the gate to future terahertz technologies

September 12, 2011

Nestled between radio waves and infrared light is the terahertz (THz) portion of the electromagnetic spectrum. By adding a nanoscale bit of graphene, researchers have found a better way to tune radiation for a THz transmitter.

Metamaterial flexible sheets could transform optics

June 6, 2013

( —New ultrathin, planar, lightweight, and broadband polarimetric photonic devices and optics could result from recent research by a team of Los Alamos National Laboratory scientists. The advances would boost security ...

Laser guided codes advance single pixel terahertz imaging

June 25, 2013

The universe is awash in terahertz (THz) waves, as harmless as they are abundant. But unlike other regions of the electromagnetic spectrum, THz has proven to be extremely difficult to manipulate in order to capture novel ...

Recommended for you

Test racetrack dipole magnet produces record 16 tesla field

November 30, 2015

A new world record has been broken by the CERN magnet group when their racetrack test magnet produced a 16.2 tesla (16.2T) peak field – nearly twice that produced by the current LHC dipoles and the highest ever for a dipole ...

Turbulence in bacterial cultures

November 30, 2015

Turbulent flows surround us, from complex cloud formations to rapidly flowing rivers. Populations of motile bacteria in liquid media can also exhibit patterns of collective motion that resemble turbulent flows, provided the ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.