Friday, July 1, 2016

Power Splitter for Terahertz Waves Developed to Improve Data Capacity in Cellular and Wi-Fi networks

A power splitter is one of the most fundamental parts of any communications network. It allows a signal to be transmitted to numerous devices and users. A team of researchers at Brown University have created such a device meant for terahertz radiation — a range of frequencies that probably will facilitate data transfer up to 100 times quicker than current Wi-Fi and cellular networks.

One of the most basic components of any communications network is a power splitter that allows a signal to be sent to multiple users and devices. Researchers from Brown University have now developed just such a device for terahertz radiation -- a range of frequencies that may one day enable data transfer up to 100 times faster than current cellular and Wi-Fi networks. (Photo Credit: Mittleman lab / Brown University)
“One of the big thrusts in terahertz technology is wireless communications,” said Kimberly Reichel, a post-doctoral researcher in Brown’s School of Engineering who led the device’s development. “We believe this is the first demonstration of a variable broadbrand power splitter for terahertz, which would be a fundamental device for use in a terahertz network.”
The device could have a number of uses, including as a part in terahertz routers that would transmit data packets to several computers, similar to routers in current Wi-Fi networks.
This innovative new device is illustrated in the Nature journal Scientific Reports.
The current Wi-Fi and cellular networks depend on microwaves, but the quantity of data that can travel on microwaves is restricted by frequency. Terahertz waves span between 100 and 10,000GHz on the electromagnetic spectrum, and possess greater frequency and thus have the potential to transmit plenty more data. Until recent times, however, terahertz has not received a lot of attention from researchers and scientists, therefore several of the standard parts for a terahertz communications network just does not exist.
Daniel Mittleman, a professor in Brown’s School of Engineering, has been involved in building some of those standard parts. Recently, his lab built the first system for terahertz multiplexing and demultiplexing, a technique of transmitting many signals via a single medium and then splitting them back out on the other side. Mittleman’s lab has also been involved in creating a unique type of lens for focusing terahertz waves.
All the parts created by Mittleman make use of parallel-plate waveguides — metal sheets capable of restraining terahertz waves and guiding them in specific directions.
“We’re developing a family of waveguide tools that could be integrated to create the appropriate signal processing that one would need to do networking,”said Mittleman, who was a co-author on the new paper along with Reichel and Brown research professor Rajind Mendis. “The power splitter is another member of that family.”
The novel device comprises many waveguides set to form a T-junction. Signal passing into the leg of the T is divided by a triangular septum at the junction, transmitting a fraction of the signal down the two arms. The triangular shape of the septum reduces the quantity of radiation that reflects back down the leg of the T, decreasing signal loss. The septum can be shifted left or right so as to vary the quantity of power that is transmitted down either arm.
We can go from an equal 50/50 split up to a 95/5 split, which is quite a range.
The septum is controlled manually in this proof-of-concept device.  Mittleman states that the process could easily be automated to facilitate dynamic switching of power output to each channel. Then it may be possible for the device to be integrated in a terahertz router.
It’s reasonable to think that we could operate this at sub-millisecond timescales, which would be fast enough to do data packet switching. So this is a component that could be used to enable routing in the manner of the microwave routers we use today.
The Brown University team aim to further tweak the new device. The subsequent step would be to initiate testing error rates in data streams transmitted via the device.
The goal of this work was to demonstrate that you can do variable power switching with a parallel-plate waveguide architecture. We wanted to demonstrate the basic physics and then refine the design.
The National Science Foundation and the W. M. Keck Foundation funded part of this project.

Abstract-Monte Carlo simulation of near-field terahertz emission from semiconductors

S. C. Corzo-Garcia, A. I. Hernandez-Serrano, E. Castro-Camus, and O. Mitrofanov
Phys. Rev. B 94, 045301 – Published 1 July 2016
We simulated the carrier dynamics in InGaAs after ultrafast photoexcitation. By using a finite-difference time-domain approach we were able to analyze the near terahertz field emission caused by the motion of such carriers. We found that both the current parallel and normal to the interface take a relevant role in the terahertz emission. We also found that the ballistic motion of the carriers after photoexcitation dominates the emission rather than diffusion.
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Abstract-Terahertz electro-optic detection using a ⟨012⟩-cut chalcopyrite ZnGeP2 crystal

B. N. Carnio1,a)S. R. Greig1C. J. Firby1K. T. Zawilski2P. G. Schunemann2 and A. Y. Elezzabi

The electro-optic detection capabilities of a 〈012〉-cut chalcopyrite ZnGeP (ZGP) crystal is investigated in the terahertz (THz) frequency regime. Our experiments attest that ZGP exhibits low THz losses and dispersion, and that phonon-polariton effects are too weak to perturb the THz pulse. Additionally, ZGP is shown to have excellent phase matching between an optical probe pulse and a THz pulse. For a 1080 m thick ZGP crystal, this phase matching yields a detection bandwidth 1.3 times greater than ZnTe and 4.8 times greater than ZnSe and GaP. Thus, ZGP has promising applications in THz time-domain spectroscopy.

Thursday, June 30, 2016

OT-CorMedix Secures First Research Collaboration in the Medical Device Space with Luna Innovations Inc.

BEDMINSTER, NJ / ACCESSWIRE / June 29, 2016 / CorMedix Inc. (NYSE MKT: CRMD), a biopharma
biopharmaceutical company focused on developing and commercializing therapeutic products for the prevention and treatment of infectious and inflammatory disease, announced today that it has entered into a material transfer agreement with Luna Innovations Inc. (NASDAQ:LUNA), a company with broad expertise in materials technology and applied R&D in the health sciences, to test the feasibility of incorporating taurolidine into electrospun nanofibers. Luna will leverage its existing government-funded research and biomaterials expertise to create nanofibers loaded with CRMD-006, CorMedix's proprietary formulation of taurolidine, to create unique scaffolds with anti-microbial and anti-inflammatory properties that can be used primarily for wound closure and burn care. Under the agreement, Luna and CorMedix will also explore opportunities to commercialize any product, invention, or derivative developed under the collaboration.

Chronic non-healing wounds and burns expose patients to risk of infections that can complicate healing and have the potential to progress into life-threatening conditions. Electrospun fiber meshes use synthetic and natural polymers to improve patient outcomes relative to conventional dressings. Unfortunately, few dressings have been developed that allow delivery of analgesics or therapeutics while effectively preventing infections. By combining CRMD-006 with Luna's electrospinning technology, if feasible, the companies may advance a novel anti-microbial medical device for use wound care that can simultaneously provide wound management, pain relief, and anti-microbial activity.

Randy Milby, chief executive officer of CorMedix, stated, "As we've discussed, identifying partnership opportunities and expanding the potential of our taurolidine platform is a key component of our growth strategy. This agreement with Luna marks our first such collaboration in the medical device space and we are optimistic about the possibility of creating nanofiber meshes with taurolidine's proven anti-microbial and anti-inflammatory properties."

My E. Chung, president and chief executive officer of Luna Innovations, added, "We are excited to have this opportunity to leverage our expertise and be a part of this significant development. Partnering with CorMedix to explore this challenge is yet another example of the unique capabilities of our Technology Development Division." Less

Abstract-A Broadband Terahertz Waveguide T-Junction Variable Power Splitter

Kimberly S. Reichel, Rajind Mendis,  Daniel M.  Mittleman

In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.