Alcatel-Lucent and BT have confirmed trial speeds of up to 1.4Tbps with a record spectral efficiency of 5.7 bits per second per Hertz (b/s/Hz) on an existing core fibre connection. This is believed to be the fastest speed ever achieved in commercial grade hardware in a real-world environment and is equivalent to transmitting 44 uncompressed HD films in a single second. The field trial was conducted over an existing fibre link between the BT Tower in London and BT's Adastral Park research campus in Suffolk. It used a new 'flexible grid' infrastructure (Flexgrid) to vary the gaps between transmission channels, usually set at 50GHz. By increasing the density of channels on the fibre, this method achieved up to 42.5 percent greater data transmission efficiency compared to standard networks.
