From UC Berkley, a new type of optical circuit has been developed by engineering Xiang Zhang and his team. Using a one-atom graphene layer over a silicon optical waveguide, an electrical signal is applied from the side of the guide to switch the light on or off. The electrical signal’s energy level, known as Fermi level, controls the amount of photons the graphene layer absorbs. When a negative voltage is applied, electrons are drawn out of the graphene sheet no longer allowing it to absorb light. And when a great enough positive voltage is applied the electrons are so packed they also can not absorb light. But an electrical level somewhere in-between lets the graphene layer completely absorb all photons. In lab results the switching was shown to reach 1Ghz, but the team suggested 500Ghz could also be reached.
This can be used as a network modulator, controlling the speed at which packets are sent through the system. This system lets pulses be pushed out as fast as they can be sent, allowing for unparalleled data speeds. Zhang explains, "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."
Pics via UC Berkley