Nokia Bell Labs, Deutsche Telekom T-Labs and the Technical University of Munich have announced that they have been able to achieve 1 terabit per second speeds over fiber in “real-world conditions”. To achieve this, they are using a modulation system called Probabilistic Constellation Shaping (PCS).
“PCS modifies the probability with which constellation points, the alphabet of the transmission, are used. Traditionally, all constellation points are used with the same frequency. PCS cleverly uses constellation points with high amplitude less frequently than those with lesser amplitude to transmit signals that, on average, are more resilient to noise and other impairments. This allows the transmission rate to be tailored to ideally fit the transmission channel, delivering up to 30 percent greater reach.”
Digging deeper into several articles, it seem that 1 Tbps is the max, since one test showed 0.8 Tbps, which was on a link over 600 KM away. There wasn’t any details on if the 600 KM link was one continuous run, or if there were repeaters involved. We will have to wait and see if this ends up being adopted in commercial products.