The Quad Small Form Factor Pluggable Double Density (QSFP-DD) Multi Source Agreement (MSA) group has released its first specification set for the data center optical transceiver. The specifications, which define mechanical, electrical, and thermal management requirements to enable multi-vendor interoperability, represent the work of 52 companies.

The MSA formed in March 2016 to create a pluggable optical module that would support transmission rates greater than the 100-Gbps QSFP28 (see "QSFP-DD MSA targets 200G, 400G optical transceivers"). While the QSFP-DD transceiver will be backwards compatible with QSFP form factors, it will feature an eight-lane electrical interface. Each lane will operate at up to 25 Gbps with non-return-to-zero (NRZ) modulation or 50 Gbps with four-level pulse amplitude modulation (PAM4). The modules therefore will support data rates up to 400 Gbps, as well as provide backward compatibility to 40 Gbps and 100 Gbps. The group says 36 QSFP-DD optical modules can fit across a single switch slot will, giving the slot up to 14.4 Tbps in aggregate capacity.

The new specifications define the module as well as a stacked height integrated cage/connector system and a single-height cage/connector system. The group had released preliminary specifications last September (see "Preliminary QSFP-DD MSA optical transceiver specification released").

Founders of the QSFP-DD MSA include Broadcom, Brocade, Cisco, Corning, Finisar, Foxconn Interconnect Technology, Huawei, Intel, Juniper Networks, Lumentum, Luxtera, Mellanox Technologies, Molex, Oclaro, and TE Connectivity. Contributors to the specification development included Amphenol, Applied Optoelectronics, APRESIA Systems, Celestica, Ciena, ColorChip, Dell EMC, Delta, Fujitsu Optical Components, Genesis, H3C, Innovium, Inphi, Ixia, Kaiam, LEONI, Lorom, Luxshare, MACOM, MaxLinear, MultiLane, NeoPhotonics, Nokia, Panduit, PHY-SI, Ranovus, Samtec, Senko, Semtech, Sicoya, Siemon, Skorpios Technologies, Source Photonics, Spirent, Sumitomo Electric, Xilinx, and Yamaichi Electronics.

The QSFP-DD form factor specification is available for free download at the QSFP-DD MSA website www.qsfp-dd.com.

http://www.lightwaveonline.com/articles/2017/03/qsfp-dd-msa-group-releases-optical-transceiver-form-factor-specification.html