Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unique properties of graphene lead to a new paradigm for low-power telecommunications

16.07.2012
Columbia Engineering pioneers ultralow-power optical information processing and frequency generation in graphene-silicon photonic circuits

New research by Columbia Engineering demonstrates remarkable optical nonlinear behavior of graphene that may lead to broad applications in optical interconnects and low-power photonic integrated circuits.


Ultralow-power optical information processing is based on graphene on silicon photonic crystal nanomembranes. Credit: Nicoletta Barolini

With the placement of a sheet of graphene just one-carbon-atom-thick, the researchers transformed the originally passive device into an active one that generated microwave photonic signals and performed parametric wavelength conversion at telecommunication wavelengths.

"We have been able to demonstrate and explain the strong nonlinear response from graphene, which is the key component in this new hybrid device," says Tingyi Gu, the study's lead author and a Ph.D. candidate in electrical engineering. "Showing the power-efficiency of this graphene-silicon hybrid photonic chip is an important step forward in building all-optical processing elements that are essential to faster, more efficient, modern telecommunications. And it was really exciting to explore the 'magic' of graphene's amazingly conductive properties and see how graphene can boost optical nonlinearity, a property required for the digital on/off two-state switching and memory."

The study, led by Chee Wei Wong, professor of mechanical engineering, director of the Center for Integrated Science and Engineering, and Solid-State Science and Engineering, will be published online in the Advance Online Publication on Nature Photonics's website on July 15 and in print in the August issue. The team of researchers from Columbia Engineering and the Institute of Microelectronics in Singapore are working together to investigate optical physics, material science, and device physics to develop next-generation optoelectronic elements.

They have engineered a graphene-silicon device whose optical nonlinearity enables the system parameters (such as transmittance and wavelength conversion) to change with the input power level. The researchers also were able to observe that, by optically driving the electronic and thermal response in the silicon chip, they could generate a radio frequency carrier on top of the transmitted laser beam and control its modulation with the laser intensity and color. Using different optical frequencies to tune the radio frequency, they found that the graphene-silicon hybrid chip achieved radio frequency generation with a resonant quality factor more than 50 times lower than what other scientists have achieved in silicon.

"We are excited to have observed four-wave mixing in these graphene-silicon photonic crystal nanocavities," says Wong. "We generated new optical frequencies through nonlinear mixing of two electromagnetic fields at low operating energies, allowing reduced energy per information bit. This allows the hybrid silicon structure to serve as a platform for all-optical data processing with a compact footprint in dense photonic circuits."

Wong credits his outstanding students for the exceptional work they've done on the study, and adds, "We are fortunate to have the expertise right here at Columbia Engineering to combine the optical nonlinearity in graphene with chip-scale photonic circuits to generate microwave photonic signals in new and different ways."

Until recently, researchers could only isolate graphene as single crystals with micron-scale dimensions, essentially limiting the material to studies confined within laboratories. "The ability to synthesize large-area films of graphene has the obvious implication of enabling commercial production of these proven graphene-based technologies," explains James Hone, associate professor of mechanical engineering, whose team provided the high quality graphene for this study. "But large-area films of graphene can also enable the development of novel devices and fundamental scientific studies requiring graphene samples with large dimensions. This work is an exciting example of both—large-area films of graphene enable the fabrication of novel opto-electronic devices, which in turn allow for the study of scientific phenomena."

Commenting on the study, Xiang Zhang, director of the National Science Foundation Nanoscale Science and Engineering Center at the University of California at Berkeley, says, "this new study in integrating graphene with silicon photonic crystals is very exciting. Using the large nonlinear response of graphene in silicon photonics demonstrated in this work will be a promising approach for ultra-low power on-chip optical communications."

"Graphene has been considered a wonderful electronic material where electron moves like an effectively massless particle in the atomically thin layer," notes Philip Kim, professor of physics and applied physics at Columbia, one of the early pioneers in graphene research and who discovered its low-temperature high electronic conductivity. "And now, the recent excellent work done by this group of Columbia researchers demonstrates that graphene is also unique electro-optical material for ultrafast nonlinear optical modulation when it is combined with silicon photonic crystal structures. This opens an important doorway for many novel optoelectronic device applications, such as ultrafast chip-scale high-speed optical communications."

This research is supported by the Columbia Energy Frontier Research Center program, which is funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, and the Columbia Optics and Quantum Electronics IGERT (Integrative Graduate Education and Research Traineeship) program, which is funded by the National Science Foundation.

Columbia Engineering

Columbia University's Fu Foundation School of Engineering and Applied Science, founded in 1864, offers programs in nine departments to both undergraduate and graduate students. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to NSF-NIH funded centers in genomic science, molecular nanostructures, materials science, and energy, as well as one of the world's leading programs in financial engineering. These interdisciplinary centers are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of modern society's more difficult challenges. http://www.engineering.columbia.edu/

Holly Evarts | EurekAlert!
Further information:
http://www.columbia.edu

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Happy hour for time-resolved crystallography

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.

The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.

Im Focus: Modular OLED light strips

At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.

Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Novel mechanism of electron scattering in graphene-like 2D materials

17.09.2019 | Materials Sciences

Novel anti-cancer nanomedicine for efficient chemotherapy

17.09.2019 | Health and Medicine

Fungicides as an underestimated hazard for freshwater organisms

17.09.2019 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>