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Primeur weekly 2011-05-16

EuroFlash

Jülich makes a crutial step towards Exascale computer with the introduction of hybrid clusters using Tesla 20-series GPU's ...

Cray signs contract to upgrade and expand the Cray XE6 supercomputer at the University of Edinburgh ...

Cray reports first quarter 2011 financial results ...

Electromechanics also operates at the nanoscale ...

ICM selects IBM to fuel national science ...

USFlash

Carbon, carbon, everywhere; But not from the Big Bang ...

Cisco Networking Solutions increase security and mobility with Cloud services for branch offices ...

Xerox and Cisco to form alliance to deliver Cloud services; Combine network intelligence and print management ...

Cray and Sandia establish a Supercomputing Institute for Learning and Knowledge Systems ...

EMC Isilon delivers world's largest single file system for big data ...

EMC and Box deliver enterprise content management mobility through the Cloud ...

EMC enables service providers to accelerate customers' journey to Cloud computing ...

EMC delivers "Cloud to Ground" root-cause analysis for data centres ...

EMC delivers Hadoop 'big data' analytics to the enterprise ...

New EMC Ionix UIM software simplifies Cloud infrastructure management ...

EMC connects VNX to the Cloud with new Cloud Tiering Appliance ...

Graphene optical modulators could lead to ultrafast communications ...

HP puts data storage on a diet and guarantees capacity reduction ...

HP launches high-performance FlexNetwork solutions for video and mobile computing ...

HP readies enterprises for the future with FlexNetwork architecture ...

IBM delivers technology to help clients protect and retain "Big Data" ...

Primerica selects new IBM zEnterprise mainframe server for smarter infrastructure ...

Proton dripping tests a fundamental force in nature ...

Raritan's data centre energy management software gets a new dashboard with forecasting tools and gauges to track and visualize key energy metrics ...

Red Hat revolutionizes the private and hybrid Cloud market ...

Rice doubles supercomputing capacity ...

Student, 16, invents new drug cocktail to fight cystic fibrosis, wins Canadian biotech challenge ...

Graphene optical modulators could lead to ultrafast communications

8 May 2011 Berkeley - Scientists at the University of California, Berkeley, have demonstrated a new technology for graphene that could break the current speed limits in digital communications. The team of researchers, led by UC Berkeley engineering professor Xiang Zhang, built a tiny optical device that uses graphene, a one-atom-thick layer of crystallized carbon, to switch light on and off. This switching ability is the fundamental characteristic of a network modulator, which controls the speed at which data packets are transmitted. The faster the data pulses are sent out, the greater the volume of information that can be sent. Graphene-based modulators could soon allow consumers to stream full-length, high-definition, 3D movies onto a smartphone in a matter of seconds, the researchers said.

"This is the world's smallest optical modulator, and the modulator in data communications is the heart of speed control", stated Xiang Zhang, who directs a National Science Foundation (NSF) Nanoscale Science and Engineering Center at UC Berkeley. "Graphene enables us to make modulators that are incredibly compact and that potentially perform at speeds up to ten times faster than current technology allows. This new technology will significantly enhance our capabilities in ultrafast optical communication and computing."

In this latest work, described in the May 8 advanced on-line publication of the journalNature, researchers were able to tune the graphene electrically to absorb light in wavelengths used in data communication. This advance adds yet another advantage to graphene, which has gained a reputation as a wonder material since 2004 when it was first extracted from graphite, the same element in pencil lead. That achievement earned University of Manchester scientists Andre Geim and Konstantin Novoselov the Nobel Prize in Physics last year.

Xiang Zhang worked with fellow faculty member Feng Wang, an assistant professor of physics and head of the Ultrafast Nano-Optics Group at UC Berkeley. Both Xiang Zhang and Feng Wang are faculty scientists at Lawrence Berkeley National Laboratory's Materials Science Division.

"The impact of this technology will be far-reaching", stated Feng Wang. "In addition to high-speed operations, graphene-based modulators could lead to unconventional applications due to graphene's flexibility and ease in integration with different kinds of materials. Graphene can also be used to modulate new frequency ranges, such as mid-infrared light, that are widely used in molecular sensing."

Graphene is the thinnest, strongest crystalline material yet known. It can be stretched like rubber, and it has the added benefit of being an excellent conductor of heat and electricity. This last quality of graphene makes it a particularly attractive material for electronics.

"Graphene is compatible with silicon technology and is very cheap to make", stated Ming Liu, post-doctoral researcher in Xiang Zhang's lab and co-lead author of the study. "Researchers in Korea last year have already produced 30-inch sheets of it. Moreover, very little graphene is required for use as a modulator. The graphite in a pencil can provide enough graphene to fabricate 1 billion optical modulators."

It is the behaviour of photons and electrons in graphene that first caught the attention of the UC Berkeley researchers. The researchers found that the energy of the electrons, referred to as its Fermi level, can be easily altered depending upon the voltage applied to the material. The graphene's Fermi level in turn determines if the light is absorbed or not.

When a sufficient negative voltage is applied, electrons are drawn out of the graphene and are no longer available to absorb photons. The light is "switched on" because the graphene becomes totally transparent as the photons pass through. Graphene is also transparent at certain positive voltages because, in that situation, the electrons become packed so tightly that they cannot absorb the photons.

The researchers found a sweet spot in the middle where there is just enough voltage applied so the electrons can prevent the photons from passing, effectively switching the light "off".

"If graphene were a hallway, and electrons were people, you could say that, when the hall is empty, there's no one around to stop the photons", stated Xiaobo Yin, co-lead author of theNaturepaper and a research scientist in Xiang Zhang's lab. "In the other extreme, when the hall is too crowded, people can't move and are ineffective in blocking the photons. It's in between these two scenarios that the electrons are allowed to interact with and absorb the photons, and the graphene becomes opaque."

In their experiment, the researchers layered graphene on top of a silicon waveguide to fabricate optical modulators. The researchers were able to achieve a modulation speed of 1 gigahertz, but they noted that the speed could theoretically reach as high as 500 gigahertz for a single modulator.

While components based upon optics have many advantages over those that use electricity, including the ability to carry denser packets of data more quickly, attempts to create optical interconnects that fit neatly onto a computer chip have been hampered by the relatively large amount of space required in photonics.

Light waves are less agile in tight spaces than their electrical counterparts, the researchers noted, so photon-based applications have been primarily confined to large-scale devices, such as fiber optic lines.

"Electrons can easily make an L-shaped turn because the wavelengths in which they operate are small", stated Xiang Zhang. "Light wavelengths are generally bigger, so they need more space to maneuver. It's like turning a long, stretch limo instead of a motorcycle around a corner. That's why optics require bulky mirrors to control their movements. Scaling down the optical device also makes it faster because the single atomic layer of graphene can significantly reduce the capacitance - the ability to hold an electric charge - which often hinders device speed."

Graphene-based modulators could overcome the space barrier of optical devices, the researchers said. They successfully shrunk a graphene-based optical modulator down to a relatively tiny 25 square microns, a size roughly 400 times smaller than a human hair. The footprint of a typical commercial modulator can be as large as a few square millimeters.

Even at such a small size, graphene packs a punch in bandwidth capability. Graphene can absorb a broad spectrum of light, ranging over thousands of nanometers from ultraviolet to infrared wavelengths. This allows graphene to carry more data than current state-of-the-art modulators, which operate at a bandwidth of up to 10 nanometers, the researchers said.

"Graphene-based modulators not only offer an increase in modulation speed, they can enable greater amounts of data packed into each pulse", stated Xiang Zhang. "Instead of broadband, we will have 'extremeband'. What we see here and going forward with graphene-based modulators are tremendous improvements, not only in consumer electronics, but in any field that is now limited by data transmission speeds, including bioinformatics and weather forecasting. We hope to see industrial applications of this new device in the next few years."

Other UC Berkeley co-authors of this paper are graduate student Erick Ulin-Avila and post-doctoral researcher Thomas Zentgraf in Xiang Zhang's lab; and visiting scholar Baisong Geng and graduate student Long Ju in Feng Wang's lab.

This work was supported through the Center for Scalable and Integrated Nano-Manufacturing (SINAM), an NSF Nanoscale Science and Engineering Center. Funding from the Department of Energy's Basic Energy Science program at Lawrence Berkeley National Laboratory also helped support this research.

Source: University of California - Berkeley

Back to Table of contents

Primeur weekly 2011-05-16

EuroFlash

Jülich makes a crutial step towards Exascale computer with the introduction of hybrid clusters using Tesla 20-series GPU's ...

Cray signs contract to upgrade and expand the Cray XE6 supercomputer at the University of Edinburgh ...

Cray reports first quarter 2011 financial results ...

Electromechanics also operates at the nanoscale ...

ICM selects IBM to fuel national science ...

USFlash

Carbon, carbon, everywhere; But not from the Big Bang ...

Cisco Networking Solutions increase security and mobility with Cloud services for branch offices ...

Xerox and Cisco to form alliance to deliver Cloud services; Combine network intelligence and print management ...

Cray and Sandia establish a Supercomputing Institute for Learning and Knowledge Systems ...

EMC Isilon delivers world's largest single file system for big data ...

EMC and Box deliver enterprise content management mobility through the Cloud ...

EMC enables service providers to accelerate customers' journey to Cloud computing ...

EMC delivers "Cloud to Ground" root-cause analysis for data centres ...

EMC delivers Hadoop 'big data' analytics to the enterprise ...

New EMC Ionix UIM software simplifies Cloud infrastructure management ...

EMC connects VNX to the Cloud with new Cloud Tiering Appliance ...

Graphene optical modulators could lead to ultrafast communications ...

HP puts data storage on a diet and guarantees capacity reduction ...

HP launches high-performance FlexNetwork solutions for video and mobile computing ...

HP readies enterprises for the future with FlexNetwork architecture ...

IBM delivers technology to help clients protect and retain "Big Data" ...

Primerica selects new IBM zEnterprise mainframe server for smarter infrastructure ...

Proton dripping tests a fundamental force in nature ...

Raritan's data centre energy management software gets a new dashboard with forecasting tools and gauges to track and visualize key energy metrics ...

Red Hat revolutionizes the private and hybrid Cloud market ...

Rice doubles supercomputing capacity ...

Student, 16, invents new drug cocktail to fight cystic fibrosis, wins Canadian biotech challenge ...