Terahertz radiation could one day provide the backbone for wireless systems that can deliver data up to one hundred times faster than today's cellular or Wi-Fi networks. But there remain many technical challenges to be solved before terahertz wireless is ready for prime time.
Researchers from Brown University have taken a major step toward addressing one of those challenges. They've developed what they believe to be the first system for multiplexing terahertz waves. Multiplexers are devices that enable separate streams of data to travel through a single medium. It's the technology that makes it possible for a single cable to carry multiple TV channels or for a fiber optic line to carry thousands of phone calls at the same time.
All communications networks need some form of multiplexing -- the ability to send multiple data streams through a single medium. Researchers from Brown have used a leaky wave antenna to separate terahertz waves by frequency. The work provides a viable multiplexing and demultiplexing strategy for future terahertz data networks, which have the potential to deliver data many times faster than today's cellular or Wi-Fi networks.
Credit: Mittleman Lab / Brown University
"Any terahertz communications application is going to need some form of multiplexing and demultiplexing," said Daniel Mittleman, professor of engineering at Brown and senior author of a paper describing the new device. "This is, to our knowledge, the first time anyone has demonstrated a viable strategy for multiplexing in the terahertz range."
The research was published September 14 in Nature Photonics.
Today's cellular and Wi-Fi networks rely on microwaves to carry voice conversations and data. But the increasing demands for data transfer are quickly becoming more than microwaves can handle. Terahertz waves have a much higher frequency and therefore more potential bandwidth. Scientists and engineers have only recently begun exploring the potential of terahertz waves, however. As a result, many of the components for a terahertz wireless network -- including multiplexers -- have not yet been developed.
The multiplexer that Mittleman and his colleagues have been working on makes use of what's known as a leaky wave antenna. In this case, the antenna is made from two metal plates placed in parallel to form a waveguide. One of the plates has a small slit in it. As terahertz waves travel down the waveguide, some of the radiation leaks out of the slit. It turns out that terahertz waves leak out a different angles depending on their frequency.
"That means if you put in 10 different frequencies between the plates -- each of them potentially carrying a unique data stream -- they'll come out at 10 different angles," Mittleman said. "Now you've separated them and that's demultiplexing."
On the other end, a receiver could be tuned to accept radiation at a particular angle, thus receiving data from only one stream.
"We think it's definitely a reasonable solution to meet the needs of a terahertz communication network," said Nicholas Karl, a graduate student at Brown and the paper's lead author. Karl led the experiments on the device with fellow graduate student Robert McKinney. Other authors on the study are Rajind Mendis, a research professor at Brown, and Yasuaki Monnai from Keio University in Tokyo.
One of the advantages to the approach, the researchers say, is that by adjusting the distance between the plates, it's possible to adjust the spectrum bandwidth that can be allocated to each channel. That could be especially useful when such a device is deployed for use in a data network.
"For example, if one user suddenly needs a ton of bandwidth, you can take it from others on the network who don't need as much just by changing the plate spacing at the right location," Mittleman said.
The group plans to continue its work to refine the device. A research group from Osaka University is collaborating with Mittleman's group to implement the device in a prototype terahertz network they're building.
"This is a first-generation, proof-of-concept device," Karl said. "There are still things we can do to improve it and we'll continue to study it."
Mittleman hopes that the work will challenge other researchers to start developing components for terahertz networks.
"The biggest impact this may have is it may just be the kick that people need to start thinking about this issue," Mittleman said. "That means they'll start coming up with clever ideas that are entirely different from this one."
The work was supported by the National Science Foundation and the W.M. Keck Foundation.
Note to Editors:
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.
Kevin Stacey | EurekAlert!
UT professor develops algorithm to improve online mapping of disaster areas
29.11.2016 | University of Tennessee at Knoxville
New standard helps optical trackers follow moving objects precisely
23.11.2016 | National Institute of Standards and Technology (NIST)
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy