Researchers at the Karlsruhe University have managed to beat the speed record they owned by transmitting last year 10 Tbps on a fibre using a single laser beam. Now they have transmitted 26 Tbps!
Interestingly, they say that this new achievement is just showing that we have not received the physical limits of transmission speed (or rather capacity, since the speed never changes, being the speed of the electromagnetic field).
It is always nice to see how far research can “push the envelope” even though this kind of speed are not viable today for commercial exploitation. However, in a commercial fibre we have already reached multi Tbps capacity by inserting several laser beams into the fibre with DWDMA (Dense Wavelength Division Multiple Access). By increasing the capacity of each single beam we can multiply the overall capacity by adding more lasers. However, at a certain point, at least today, we need to convert the optical signal into an electric one (and the other way around) and here is where we have the bottleneck. The cost of increasing the speed of electronics (in the electro-optical conversion) skyrockets with present technology once you push beyond 40 Gbps.
In the future, however, we will see both an increase of speed in the optical-electrical conversion and the optical networks will be able to extend much further, possibly right into the computer chip where some researchers have started to use optical bus for communication in the chip and are experimenting with optical processing.
It looks like the thresholds of what is impossible keep moving as we get closer.