Fibre optic spectral efficiency trial achieves 1.4Tbps

Alcatel-Lucent is claiming a new world best in spectral efficiency after tests with British telco incumbent BT that reached an encoding density of 5.7 bits per second and Hertz over a 410 kilometre fibre-optic link between Ipswich and London.

The high spectral efficiency was achieved by increasing the density of the wavelength-divided multiplexed channels, flexibly reducing the spacing between these from the standard 50GHz to 35GHz. 

In doing so, Alcatel-Lucent said it achieved up to 42.5 percent greater transmission efficiency compared to standard fibre-optic dense wave division multiplexing (DWDM) networks.

The ALU 1830 Photonic Service Switch used in the trial.

The trial link between BT's London premises and Alcatel-Lucent's Ipswich laboratory used so-called alien wavelengths; these are different colour wavelengths integrated into existing fibre networks via external equipment without the need for transponders.

Alien wavelengths are mooted as a way for network operators to extend capacity on existing links without having to update the physical optical infrastructure.

Seven alien wavelength channels, each with 200 gigabit per second capacity, were bonded into a super channel for a total of 1.4Tbps running on top of BT's existing optical network for the trial.

Alcatel-Lucent said the trial was conducted with production equipment that showed stable and error-free operation with a mix of 40Gbps and 100Gbps wavelengths.