Fujitsu, NTT and NEC have begun work on 400-Gbit/s digital coherent optical networking technology, hoping it will result in the world’s highest-capacity optical networks (capable of 24 Terabits/s fiber-class transmissions). While the three companies haven’t yet laid out a commercialization roadmap, they’re aiming for 2014 as a completion date for the research.
The project, which will receive funding from Japan’s Ministry of Internal Affairs and Communications (MIC), is a natural extension of an existing development partnership between the trio, which have already co-developed 100-Gbit/s components; a LSI-DSP component they produced in 2012 is widely viewed as the most-used on the market.
The companies plan on incorporating dual-polarization quadrature phase shift keying (DP-QPSK), currently in use for 100-Gbit transmissions, together with dual-polarization 16 quadrature amplitude modulation (DP-16QAM), which takes advantage of an even greater number of quadrature carriers, into a high-density 60-channel fiber; in theory, the final result will hit that 24-terabit transmission threshold.
The three firms also hope to develop compensation technology for non-linear effects, which can act as the limiting factor for long-distance transmission of multiple quadrature modulated signals. (For example, stimulated Raman scattering is the effect where vibrating silica molecules scatter light; for more, Govind Agrawal’s paper provides some additional explanation and math.) If they implement correctly, the technology will also include a host of modulation techniques, which in turn would allow the construction of flexible network architecture.
The trio didn’t state their target transmission distance, only that they hoped to achieve twice the distance of 100-Gbit optical components.
The Fujitsu/NTT/NEC work comes as 400-Gbit Ethernet is being eyed as a practical replacement for the current Ethernet generation, and viable alternative to an outright leap to terabit Ethernet. But there’s been little movement towards developing the specification, aside from debates on the rationale for moving to 400-Gbit/s rather than 1 terabit.