Better than X-rays: A more powerful terahertz imaging system

Mar 27, 2013
Mona Jarrahi, assistant professor of electrical engineering and computer science, and members of the research team that recently developed a super-sensitive terahertz source and detector system. Pictured are Ning Wang and Christopher Berry, doctoral students in electrical engineering and computer science, and Mohammad Reza Hashemi, a postdoctoral researcher in the same department. Photo courtesy of Mona Jarrahi

(Phys.org) —Low-energy terahertz radiation could potentially enable doctors to see deep into tissues without the damaging effects of X-rays, or allow security guards to identify chemicals in a package without opening it. But it's been difficult for engineers to make powerful enough systems to accomplish these promising applications.

Now an electrical engineering research team at the University of Michigan has developed a laser-powered terahertz source and detector system that transmits with 50 times more power and receives with 30 times more sensitivity than existing technologies. This offers 1,500 times more powerful systems for imaging and sensing applications.

"With our higher-sensitivity terahertz system, you could see deeper into tissues or sense small quantities of and explosives from a farther distance. That's why it's important," said Mona Jarrahi, U-M assistant professor of electrical engineering and computer science and leader of the project.

Jarrahi's research team accomplished this by funneling the to specifically selected locations near the device's that feeds the antenna that transmits and receives the terahertz signal.

Their approach enables light to hitch a ride with on the surface of the metallic electrodes to form a class of called surface plasmon waves. By coupling the with surface plasmon waves, the researchers created a funnel to carry light into nanoscale regions near device electrodes.

The excited waves carry optical photons where they need to be much faster and much more efficiently, Jarrahi said.

"When you want to generate or detect terahertz radiation, you have to convert photons to electron hole pairs and then quickly drift them to the contact electrodes of the device. Any delay in this process will reduce the device efficiency," Jarrahi said. "We designed a structure so that when photons land, most of them appear to be right next to the contact electrodes."

According to Jarrahi, the output power of the terahertz sources and the sensitivity of the terahertz detectors can be increased even further by designing optical funnels with tighter focusing capabilities.

"This is a fantastic piece of engineering," said Ted Norris, U-M professor of electrical engineering and computer science. "It gets right to the central issue in photoconductive terahertz devices, which is collecting all the charge. Since every application benefits from increased sensitivity, for example, reduced data acquisition time or increased standoff distance, I expect this approach to be implemented widely."

Explore further: X-ray powder diffraction beamline at NSLS-II takes first beam and first data

More information: The study, "Significant performance enhancement in photoconductive terahertz optoelectronics by incorporating plasmonic contact electrodes," is published in the current edition of Nature Communications.

Related Stories

Terahertz imaging goes the distance

Apr 26, 2007

Terahertz (THz) radiation, or far-infrared light, is potentially very useful for security applications, as it can penetrate clothing and other materials to provide images of concealed weapons, drugs, or other objects. However, ...

Graphene may open the gate to future terahertz technologies

Sep 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.

Photonics: strong vibrations

May 10, 2012

A new approach to generating terahertz radiation will lead to new imaging and sensing applications. The low energy of the radiation means that it can pass through materials that are otherwise opaque, opening ...

Team develops new metamaterial device

Feb 24, 2009

An engineered metamaterial proved it can function as a state-of-the-art device in the complex terahertz range of the electromagnetic spectrum, setting a standard of performance for modulating tiny waves of radiation, according ...

Researchers mine the 'Terahertz gap'

Feb 04, 2008

Research underway at the University of Leeds will provide a completely fresh insight into the workings of nano-scale systems, and enable advances in the development of nano-electronic devices for use in industry, medicine ...

Recommended for you

Particles, waves and ants

Nov 26, 2014

Animals looking for food or light waves moving through turbid media – astonishing similarities have now been found between completely different phenomena.

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

mb9
4.2 / 5 (5) Mar 27, 2013
Another step closer to the tricorder.
Osiris1
1 / 5 (2) Mar 28, 2013
Looks like a refinement of old Clinton era Attorney General Janet Reno's airport scanner that was really good at seeing people naked without having to remove their clothes...semi-remotely. Voyeurs will love it...but then cancers, if they had a mind, would absolutely hate it. No place to hide. Same for terrorists with plastic grenades in their colons. Guess this makes a true anal probe...justifiable in the light of finding future terrorists with no concern for humanity, themselves included.
Q-Star
1 / 5 (2) Mar 28, 2013
(in visible spectrum only, I admit...).


Is that why we can't see the aether & ducks?
Steven_Anderson
1.7 / 5 (3) Mar 31, 2013
I wonder what the size of the device is at this time? Would it be size wise in the range where you could integrate it in a tricorder device? http://rawcell.com

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.