New CWDM8 MSA specifications cover 400 Gbps over 2 km

Members of the CWDM8 Multisource Agreement (MSA) have released a technical specification that covers 400-Gbps optical transmission at distances up to 2 km over duplex single-mode fiber. The group says a companion specification for 400-Gbps application of 10 km should be ready by the end of the year.

Members of the CWDM8 Multisource Agreement (MSA) have released a technical specification that covers 400-Gbps optical transmission at distances up to 2 km over duplex single-mode fiber. The group says a companion specification for 400-Gbps application of 10 km should be ready by the end of the year.

The CWDM8 MSA announced its formation this past September with an eye toward addressing 400-Gbps applications using NRZ modulation on the optical end while maintaining compatibility with 50-Gbps per lane electrical interfaces such as those the P302.3bs 400 Gigabit Ethernet Task Force envisions (see "CWDM8 MSA targets 400G at 2 km, 10 km via NRZ wavelengths"). The MSA specifications could be applied to QSFP-DD, OSFP, and COBO optical transceivers and modules.

The use of NRZ for the optical transmission contrasts with the upcoming 400 Gigabit Ethernet specifications, which are expected to use PAM4 in single-mode fiber applications when the Task Force completes its work, a milestone expected to be reached by the end of this year. The MSA asserts the use of NRZ modulation, already common among data center transceivers, will enable compliant modules to reach the market more quickly than those based on PAM4 or other higher-order modulation formats.

Members of the CWDM8 MSA include Accton, Applied Optoelectronics, Barefoot Networks, Credo Semiconductor, Hisense, Innovium, Intel, MACOM, Mellanox, Neophotonics, New H3C Technologies, and Rockley Photonics. All but Applied Optoeletronics and New H3C Technologies are founding members.

The specification is available for download at www.cwdm8-msa.org.

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