13-10-2012, 02:52 PM
Graphene and its uses in optical interconnects.
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What is Graphene?
Graphene is a flat monolayer of carbon atoms tightly packed into a two dimensional (2D) honeycomb lattice, and is a basic building block for graphitic materials of all other dimensionalities. It can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite.
What is a fullerene?
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube.
Graphene is an isolated atomic plane of graphite. Producing graphene by the exfoliation techniques is one of the most expensive methods, however, to use graphene in the optical interconnects, the isolation of each graphene layer is necessary. The bonds between the layers of graphene are very weak and hence can be broken easily rather than the bond between the various constituent carbon molecules having a sp2 configuration.
OPTICAL INTERCONNECTS:
What are optical interconnects?
Optical interconnect is a way of communication by optical cables. Compared to traditional cables, optical wires are capable of a much higher bandwidth, from 10 Gbit/s up to 100 Gbit/s.
Optical fiber can be used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters.
OPTICAL INTERCONNECTS & GRAPHENE:
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. 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.
Tingyi Gu, the study's lead author and a Ph.D. candidate in electrical engineering said that the strong and non linear behavior of grapheme is the key component in the hybrid device and 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.
Chee Wei Wong, professor of mechanical engineering and his team 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.