Graphene-based terahertz devices: The wave of the future

May 02, 2012
Graphene-based terahertz devices: The wave of the future

People use electromagnetic energy every day … watching television, listening to the radio, popping corn with a microwave, taking an X-ray or using a cellphone. This energy travels in the form of waves, which are widely used in electronic and wireless devices.

One of the hottest areas of the electromagnetic spectrum being explored today is the (THz) range. Terahertz waves, lying between microwave and optical frequencies, offer improved performance for a variety of applications in everyday life. For instance, THz waves can carry more information than radio/microwaves for communications devices. They also provide medical and biological images with higher resolution than microwaves, while offering much smaller potential harm of exposure than X-rays.

Researchers at the University of Notre Dame have shown that it is possible to efficiently manipulate THz electromagnetic waves with atomically thin layers. This achievement, which was recently published in Nature Communications, sets the stage for development of compact, efficient and cost-effective devices and systems operating in the THz band.

“A major bottleneck in the promise of THz technology has been the lack of efficient materials and devices that manipulate these energy waves,” says Berardi Sensale-Rodriguez, a graduate student in the Department of Electrical Engineering at Notre Dame. “Having a naturally two-dimensional material with strong and tunable response to THz waves — for example, graphene — gives us the opportunity to design THz devices achieving unprecedented performance.”

The terahertz team — graduate students Sensale-Rodriguez, Rusen Yan, Kristof Tahy and Tian Fang; research assistant professors Michelle M. Kelly, through Center for Nano Science and Technology (NDnano), and Lei Liu, in conjunction with Advanced Diagnostics and Therapeutics at Notre Dame (AD&T); visiting research assistant professor Wan Sik Hwang, with Midwest Institute for Nanoelectronics Discovery (MIND); associate professor Debdeep Jena and John Cardinal O’Hara, C.S.C., Associate Professor Huili (Grace) Xing — has demonstrated the first proof of concept prototype of a graphene-based THz modulator, a device enabled solely by intraband transitions in graphene.

Graphene, an atom-thick semiconductor material, has shown promising electrical, mechanical and thermal properties leading to the recent demonstration of fast transistors, flexible/transparent electronics, optical devices and now terahertz active components.

“Graphene has been touted as an ideal platform to discover new, as well as prove/dispute existing, physical phenomena since 2004," Xing said. "That is what two physicists in the United Kingdom, Andre Geim and Konstantin Novoselov, were awarded the Nobel Prize for in 2010. However, very few real-world applications of graphene have emerged to date. Using graphene to manipulate THz waves is one of such applications. This Nature Communication paper documented our first experimental effort to realize the predictions in our paper published in Applied Physics Letters last year. Devices with better performance continue rolling out of our laboratories.

“Though Professor Jena and I formed the vision to use two-dimensional electron gas to manipulate THz waves back in 2006, it was not until Michelle, Lei and Berardi joined us that this piece of work was possible,” Xing added.

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User comments : 8

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Lurker2358
2.1 / 5 (7) May 02, 2012
Probably won't make much difference as a medical scanner.

First you get strung along for 6 months to a year before anybody decides to do a test on you that has a real chance of diagnosing anything. Then when they do a scan, it'll required a new "specialist" and even higher medical bills, and they probably still won't diagnose you properly.
Royale
1 / 5 (1) May 02, 2012
Probably won't make much difference as a medical scanner.

First you get strung along for 6 months to a year before anybody decides to do a test on you that has a real chance of diagnosing anything. Then when they do a scan, it'll required a new "specialist" and even higher medical bills, and they probably still won't diagnose you properly.

Guess you've had some bad experiences medically before, huh?
DaFranker
2.4 / 5 (5) May 02, 2012
Graphene has been touted as an ideal platform to discover new, as well as prove/dispute existing, physical phenomena since 2004," Xing said.


One cannot "prove" or "dispute" physical phenomena. If the quote is accurate, this is a comical and/or enlightening slip. Physical phenomena is observed; it is an observable manifestation of what actually happens. From this, we devise "theories", "hypotheses", "conjectures" and so on that attempt to predict or classify these phenomena. *Those* can be debated over.

Guess you've had some bad experiences medically before, huh?

As has, statistically, most users of canadian (and I suspect North American in general, though I don't remember seeing any such stats) hospitals. The exact statistics were much higher than 50%, which is why I make this claim despite not remembering the numbers.
Lurker2358
1.8 / 5 (5) May 02, 2012
Guess you've had some bad experiences medically before, huh?


If only medical doctors were as good as a Vet.

A vet has to both identify the problem and treat it, given a patient who cannot communicate their symptoms.

A doctor?

You can give them a list of your symptoms and they are like, "I got no clue what that is." And then the bastard doesn't even run a test to find out either. CBC and metabolic panel don't really diagnose anything other than the most obvious stuff, but that's about all they'll do unless you're already half dead a time or two.

Patients should be able to do a "Vet" test on doctors.

If the doctor can tell you your symptoms without you telling him first, then maybe he can actually treat you.
Eventide
5 / 5 (1) May 02, 2012
Maybe if THz imaging advances, you can just email to a radiologist the image you took of yourself on your iphone. He can then reply with a Dx and Rx and you can pick up your prescription on the way home.
ECOnservative
2 / 5 (7) May 02, 2012
One step closer to the "autodoc" of sci-fi fame. Can't happen fast enough for me. The existing medical priesthood, while good and useful, comes at too high a price.
bredmond
not rated yet May 02, 2012
Maybe if THz imaging advances, you can just email to a radiologist the image you took of yourself on your iphone. He can then reply with a Dx and Rx and you can pick up your prescription on the way home.


or the iphone itself can diagnose the problem. no need for the radiologist...except if you need a perscription of course. iphones cant do that.
bluehigh
1 / 5 (3) May 02, 2012
except if you need a prescription of course. iPhones cant do that.


In the words of Homer .. "So far",

A THz iPhone with a retina 4X display viewing Google Earth in real time would be awesome.