“This demonstration makes use of spatial division multiplexing (SDM) over multi-core optical fibres (MCFs) and a newly developed high-speed spatial optical switch system, enabling full packet-granularity,” said the organisation. “We believe this data-centre network provides a significant improvement of network efficiency and end-to-end energy consumption per bit compared to today’s optical circuit, fully-electronic packet switching networks.”

The switch can handle seven cores in a fibre, switching all cores simultaneously in 80ns.

Multiple electro-absorption optical switch elements are used with “several nanoseconds switching speed”, said NICT and the associated controller can read the destination address of packets and control multiple electro-absorption switches simultaneously.

NICT built a time-slotted optical network test bed, capable of achieving full packet granularity.

It used 64 wavelength channels, modulated at 32Gbaud with polarisation division multiplexing (PDM) quadrature phase shift keying (QPSK).

“This delivers a nominal capacity of 53.3Tbit/s,” said NICT, through three multi-core fibre segments: 28km of 19 core fibre, 10km of 19 core and 2km of seven-core.

On each fibre, seven cores were used to carry information signals.

The results of this work were presented recently at the 43rd European Conference on Optical Communications (ECOC) in Gothenburg, Sweden.

The paper was: ‘Experimental demonstration of a 53 Tb/s coherent SDM-TDM add/drop/through optical network with time-division spatial super-channels and high-speed joint switching system’.