Mark.JUK writes "The United Kingdom's national telecoms operator, BT, has successfully teamed up with Alcatel-Lucent to conduct a field trial that delivered real-world data speeds of 1.4 Terabits per second over an existing commercial-grade 410km fiber optic link. The trial used a 'record spectral efficiency' of 5.7 bits per second per Hertz and Flexgrid technology to vary the gaps between transmission channels for 42.5% greater data transmission efficiency than today's standard networks. The speed was achieved by overlaying an 'Alien Super Channel' (i.e. it operates transparently on top of BT's existing optical network), which bundled together 7 x 200Gbps (Gigabits per second) channels and then reduced the 'spectral spacing' between the channels from 50GHz to 35GHz using the 400Gb/s Photonic Services Engine (PSE) technology on the 1830 Photonic Service Switch (PSS). It's hoped that this could help boost capacity to those who need it without needing to lay expensive new fiber cables."