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.

Researchers from the University of Notre Dame in Indiana have harnessed another one of graphene's remarkable properties to better control a relatively untamed portion of the : the terahertz band.

Terahertz radiation offers tantalizing new opportunities in communications, medical imaging, and chemical detection. Straddling the transition between the highest energy and the lowest energy , terahertz waves are notoriously difficult to produce, detect, and modulate. Modulation, or varying the height of the terahertz waves, is particularly important because a modulated signal can carry information and is more versatile for applications such as chemical and biological sensing. Some of today's most promising terahertz technologies are based on small semiconductor transistor-like structures that are able to modulate a terahertz signal at room temperature, which is a significant advantage over earlier modulators that could only operate at extremely .

Unfortunately, these transistor-like devices rely on a thin layer of metal called a "metal gate" to tune the terahertz signal. This metal gate significantly reduces the signal strength and limits how much the signal can be modulated to a lackluster 30 percent. As reported in the AIP's journal , by replacing the metal gate with a single layer of graphene, the researchers have predicted that the modulation range can be significantly expanded to be in excess of 90 percent. This modulation is controlled by applying a voltage between the graphene and semiconductor. Unlike the metal gate modulator, the graphene design barely diminished the output power of the terahertz energy. Made up of a one-atom-thick sheet of , graphene boasts a host of amazing properties: it's remarkably strong, a superb thermal insulator, a conductor of electricity, and now a better means to modulate terahertz radiation.

Explore further: Simpler process to grow germanium nanowires could improve lithium ion batteries

More information: “Unique prospects for graphene-based terahertz modulators” by Berardi Sensale-Rodriguez et al. is accepted for publication in Applied Physics Letters.

Provided by American Institute of Physics

4.9 /5 (8 votes)

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Nanobanano
1 / 5 (4) Sep 12, 2011
But where are the flying cars?

Turns out, we don't need flying cars.

Besides, flying cars would make it too easy for Muslims to attack people.

Heck, eventually, we might not need cars at all. Computers, a robotic labor force, and internet will eventually negate almost all travel needs.
CHollman82
1 / 5 (1) Sep 12, 2011
Terahertz Technologies...

That's where I work! lol
that_guy
5 / 5 (1) Sep 12, 2011
in the back of my mind I was hoping that they were going to mention terahertz speed processors, even though I knew it wouldn't apply.
Nanobanano
1 / 5 (1) Sep 12, 2011
in the back of my mind I was hoping that they were going to mention terahertz speed processors, even though I knew it wouldn't apply.


I wonder what we would do with terahertz speed processors?

Global weather models would output their results in ten minutes, instead of several hours. Incredible.

I think our brains are already overloaded. Ten billion cycles per second quad core processor, and honestly, mostly all it does is sit there waiting on human input as our brains can't keep up anyway? What would INDIVIDUALS really do with say, and 8 core terahertz processor?

there's always interactive holograms and hackers, I guess.
that_guy
5 / 5 (1) Sep 12, 2011
I could see advantage coming from terahertz speed processors. First off, we wouldn't need an 8 core processor for consumer computing. A single core a thousand times faster would suffice just fine. This would have a huge effect on design and graphics. Adobe can easily bog your computer down when you're working with big or complex files.

But mainly, super computers would become much cheaper and more powerful. weather forecasting would improve substantially, to the point that the seven day forecast might actually be accurate once in a while.

And presumably, based on the promise of graphene, it would use substantially less power. Your phone could become your computer, and you would just have different docking stations for different setup needs.

I'm just grabbing the obvious, but I'm sure there are new revolutionary applications that would become available with that much of a speed jump.
Nanobanano
not rated yet Sep 12, 2011
weather forecasting would improve substantially, to the point that the seven day forecast might actually be accurate once in a while


Currently, models are actually limited by the resolution of the data input, not the computers.

The models themselves and the computers are capable of doing much better when given more complete and accurate information, which is why NOAA flies so many missions in the hurricane hunters and other atmospheric probes and drones during hurricanes.

For Irene, they even flew hurricane hunters in MONTANA because they were trying to get better data on how the troughs were setting up and how strong they were.

So terahertz processors wouldn't actually help "accuracy" of the forecase at all, as you still need better data input to make the output better.

In order to make a model twice as accurate in space and time, you'd need around 16 times more data inputs, and this would only come by more probes, buoys, radars, satellites, dropsondes, etc...
Isaacsname
not rated yet Sep 13, 2011
I wonder if it will yield new radar jamming tech..?

http://en.wikiped...cillator

Btw @ Hush, I think the S-R glissando equivalent is called a " sweep ".
that_guy
not rated yet Sep 13, 2011
weather forecasting would improve substantially, to the point that the seven day forecast might actually be accurate once in a while


Currently, models are actually limited by the resolution of the data input, not the computers.


To my knowledge, the main bottleneck at this point is having computers powerful enough to process a significantly higher number of data points. You need significantly higher resolution in order to come up with a small increase in accuracy (As you also pointed out). It follows an inverse law (Each new point multiplies the complexity), and diminishing returns, where you need exponentially more power to make significant gains.

Data gathering is interrelated - But I think we're talking about two factors that both apply.

Even with hurricanes. If they could better correlate the data outside the hurricane, they can better quantify how it affects the hurricane - but more data within the hurricane helps as well.

finitesolutions
not rated yet Sep 14, 2011
Ok a terahertz computer will accurately predict the path of the hurricane and now you need to act. Just fleeing the area is not enough. You need to revisit the building code and build hurricane proof structures and everything. Left out in the open a terahertz laptop will be reduced to an abacus by the hurricane.
What about tornadoes? Are they as easily predictable as hurricanes? i doubt it and this is why tornado proof structures need to be built also.
CHollman82
1 / 5 (1) Sep 14, 2011
Ten billion cycles per second quad core processor, and honestly, mostly all it does is sit there waiting on human input as our brains can't keep up anyway? What would INDIVIDUALS really do with say, and 8 core terahertz processor?


Even 100mhz processors on desktop PC's of the early 90's were idle 90% of the time... it's the nature of the technology... but even if it only need to do real work 1% of the time it is still exactly as beneficial to be able to do it 1000 times faster.

When I am sitting here at my PC doing nothing some background tasks will run that use maybe 1% bandwidth of the processor. But as soon as I hit the convert button in Photoshop to start a CPU bound conversion process I want it to complete in a half a second rather than 4 seconds... or even an 8th of a second, or as fast as possible...

It's just the nature of IO bound applications of personal computers, it doesn't mean that we shouldn't strive for faster components
nikola_grobler_carmody
not rated yet Sep 14, 2011
In my day we had Gigahertz....Rgds, Nikola Grobler-Carmody