Boost Up Communication Speeds With New Graphene Optical Modulators

A research team led by professor Xiang Zhang at the University of California, Berkley have developed a new electronic device using ultra thin layers of graphene which will break all the speed limit barriers in the digital communication. The device called the graphene optical modulator uses a one atom thick layer of this carbon allotroph and performs the important task of switching the light pulses on and off. In other words it performs the job of modulation of signals. With this inherent property it can be used as a network modulator that governs the rate at which the data packets are transmitted and received. This data rate increases the overall amount of data that is sent from source to destination. For getting to know the scope of this invention, you should try to imagine what it would be like to see a 3D high definition movie on your smartphone using 3G in real time. This is the speed that can be achieved with these tiny gadgets.

#-Link-Snipped-#The optical modulator is the core of an optical communication link and is responsible for deciding the speed of the data packets. These grapheme modulators are the smallest ever modulators in the world. Using these devices, ultra fast communication at speeds that are 10 to 100 times greater than the present data rate is possible.

Zhang has teamed up with fellow faculty member Feng Wang, an assistant professor of physics and head of the Ultrafast Nano-Optics Group at UC Berkeley. Both Zhang and Wang are faculty researchers at Materials Science Division of Lawrence Berkeley National Laboratory. They decided to use grapheme because it has a number of attributes that make it the designer’s perfect choice. Besides providing high speed and large bandwidth, graphene offers high flexibility, can be incorporated with silicon as well as other materials and can modulate light at newer frequencies like in the mid infrared range. It is the thinnest and most stretchable conductor of heat and electricity that is currently available.

Along with these awesome physical characteristics, these carbon sheets also have peculiar energy relations that are harnessed by the professors in the optical modulators. The Fermi energy level of the graphene can be varied as a function of the voltage applied across the material. This Fermi energy decides the absorption of light energy in the form of photons. The modulator can allow or reject the photons a passage through the modulator depending on the reverse bias applied to it. When the voltage is such that the electrons are driven out of the layer or are so tightly packed that they fail to absorb the photons, the light travels through the transparent graphene. However in the middle of these two energy levels, there is a voltage value which allows electrons to absorb the photons and block all light. In this way 1 and 0 pulses of light are sent.

In the initial tests, the scientists fabricated a layered graphene on top of a silicon rectangular optical waveguide. They obtained extreme high speed up to 1 GHz for every modulator which could be boosted up to a whopping, mind numbing speed of around 500 GHz! Everyone is well aware of the long list of advantages provided by optical communication that make its electrical counterparts look obsolete. However, the problem lies in the large size of the optical modulator that prevents its usage on computer chips. Thankfully, this shortcoming can be removed using the one atom thick layers of graphene to fabricate tiny modulators and optical interconnects that can be easily mounted on silicon chips.

The research team believes that the technology can be used in all applications that are having data transmission limitations. So we should forget broadband and get ready for the “extremeband” data speeds with this latest technology in photonics.

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