Tuesday, December 11, 2012

Fujitsu, NTT and NEC Target 400G Coherent Optical Transmission

Fujitsu, NTT and NEC are jointly developing 400 Gbps/channel-class digital coherent optical transmissions technology.

The companies have undertaken a joint R&D project that aims to leverage the technological capabilities that have enabled the commercialization of 100Gbps-class optical transmission. The R&D initiative was commissioned and is sponsored by Japan's Ministry of Internal Affairs and Communications (MIC) as part of the "Research and Development Project for the Ultra-high Speed and Green Photonic Networks".

Specifically, Fujitsu, NTT and NEC have pursued R&D on 100Gbps-class digital coherent optical communications technology as part of the MIC's "Research and Development on High Speed Optical Transport System Technologies" program (2009) and "Research and Development on Ultra-high Speed Optical Edge Node Technologies" program (2010-2011).

As a result of the previous research, a digital coherent DSP-LSI was commercialized in 2012 and is now being being deployed by each company. The new initiative will accelerate this work for 400Gbps-class optical transmissions.

The joint research project is targeting dual-polarization quadrature phase shift keying (DP-QPSK)(3), which is currently in use for 100Gbps transmissions, together with dual-polarization 16 quadrature amplitude modulation (DP-16QAM), which takes advantage of an even greater number of quadrature carriers.

The companies said that by incorporating these modulation techniques into a high-density 60-channel fiber, the technology will be able to bring about optical networks capable of 24 Tbps/fiber.  The goal will require development of the first compensation technology for nonlinear optical effects within an optical fiber.  This is the primary limiting factor standing in the way of long-distance transmission of multiple quadrature modulated signals. When employed together with enhanced-performance versions of existing compensation technologies for chromatic dispersion and polarization mode dispersion, the new technology will achieve longer transmission distances.

The companies will pursue the implementation of adaptive modulation/demodulation technology that can employ a host of modulation techniques depending on the transmission route using a single hardware device, thereby leading to the construction of flexible network


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