Researchers from of the University of California at Berkeley have discovered a new use for graphene: optical modulators that could lead to a dramatic boost in broadband speeds according to thinq_
The team, led by engineering professor Ziang Zhang, has succeeded in creating an optical modulator featuring graphene - a one-atom-thick layer of crystallised carbon seen as a possible replacement for traditional transitors in the next generation of chips.
Optical modulators, which feature the ability to switch a beam of light on or off, are the basis of modern optical communication systems - and are used in the switches that form the backbone of the Internet. While overall speed of communications is limited by several factors, one of the biggest is the speed at which the modulator can switch - and the team's graphene-based modulator promises to be very fast indeed.
"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," explained Zhang of his team's creation. "This new technology will significantly enhance our capabilities in ultrafast optical communication and computing."
Using one of the properties of graphene - its ability to turn transparent at certain positive voltages - the team was able to develop an optical modulator which uses varying voltages to alter the graphene's Fermi level. At a certain Fermi level, the light is absorbed - and the signal 'switched off.' Increasing the voltage slightly increases the Fermi level and turns the graphene transparent - meaning the signal is 'switched on.'
In the lab, the team has been able to create optical modulators operating at a speed of one gigahertz - but claim that the technology could scale to around 500GHz in a single modulator.
It's not just the ability of the graphene-based optical modulator to quickly switch on and off that makes it a breakthrough, however - but the size shrink that comes as a result of a switch in materials. With the prototype device just 25 square microns in size - around 400 times smaller than a human hair - the team's creation is significantly smaller than anything else on the market.