600-gigabit channels on a fibre by 2017
Sunday, October 16, 2016 at 7:26AM NeoPhotonics has announced an integrated coherent receiver that will enable 600-gigabit optical transmission using a single wavelength. A transmission capacity of 48 terabits over the fibre’s C-band is then possible using 80 such channels.
NeoPhotonics’ micro integrated coherent receiver operates at 64 gigabaud, twice the symbol rate of deployed 100-gigabit optical transport systems and was detailed at the recent ECOC show.
Current 100 gigabit-per-second (Gbps) coherent systems use polarisation-multiplexing, quadrature phase-shift keying (PM-QPSK) modulation operating at 32 gigabaud. “That is how you get four bits [per symbol],” says Ferris Lipscomb, vice president of marketing at NeoPhotonics.
Optical designers have two approaches to increase the data transmitted on a wavelength: they can use increasingly complex modulation schemes - such as 16 quadrature amplitude modulation (16-QAM) or 64-QAM - and they can increase the baud rate. “You double the baud rate, you double the transmission capacity,” says Lipscomb. “And using 64-QAM and 64 gigabaud, you can go to 600 gigabit per channel; of course when you do that, you reduce the reach.”
The move to the higher 64 gigabaud symbol rate will help Internet content providers increase capacity between their large-scale data centres. Typical transmission distances between sites are relatively short, up to 100km.
