Acacia Communications coherent CFP2-DCO transceiver reaches general availability

Acacia Communications (NASDAQ:ACIA) has officially launched the battle between the CFP2-DCO and CFP2-ACO optical transceivers for coherent pluggable interface domination. The company has announced that its digital coherent optics (DCO) optical module, which will support both 100- and 200-Gbps operation is now generally available.

The CFP2-DCO differs from the CFP2-ACO (for "Analog Coherent Optics") in that the transceiver contains the coherent DSP ASIC or ASSP within the module. The CFP2-ACO relies on a DSP hosted on the line card (see "OIF approves CFP2-ACO Implementation Agreement").

The CFP2-ACO therefore was easier to design, develop, and manufacture. Several optical transceiver vendors, particularly those without in-house DSP ASIC expertise, have added the CFP2-ACO to their portfolios, and the optical modules are readily available. While Acacia Communications hasn't publicly disclosed the price of its CFP2-DCO, the inclusion of the DSP device within the module likely means it will cost more than typical CFP2-ACOs. The lack of a DSP ASIC also means that the CFP2-ACO can be paired with system houses' own DSP ASICs or with merchant silicon from the likes of NEL or Inphi (via its acquisition of ClariPhy Communications). The CFP2-ACO thus has a wide addressable market – and a first-to-market advantage.

However, line cards designed for CFP2-ACOs must have a DSP device pre-installed for each port whether all ports will be used initially or not. Therefore, total line card cost using CFP2-ACOs versus -DCOs might narrow considerably. A CFP2-DCO approach also enables the addition of coherent communications capabilities to fielded systems not originally designed for such operation (as long as the systems accommodate the CFP2 form factor, of course).

The CFP2-DCO promises simpler line card designs, which means the next round of optical transport system designs and upgrades will provide the main battleground between the two optical transceiver options. (Such designs also could include whitebox optical transport systems.) While Acacia Communications is the only transceiver vendor to offer a CFP2-DCO, the fact that the OIF is creating an Implementation Agreement for such a device signals the interest the industry has in the CFP2-DCO.

The tricky part is cramming the DSP functionality into the small size of the CFP2. Acacia Communications used its 16-nm CMOS Meru DSP ASIC paired with silicon photonic IC expertise to create its module. As is the case with most of its CFP2-ACO competition, the Acacia Communications optical transceiver uses QPSK modulation for 100-Gbps operation and either 8QAM or 16QAM for 200 Gbps. It also supplies internal Layer 1 encryption.

"The Acacia 200-Gbps CFP2-DCO is the darling device of 2H17. It is unrivaled in performance and power consumption," said Cignal AI Founder and Lead Analyst Andrew Schmitt via an Acacia Communications press release.

The fact that it supports 80-km reach positions the device as a competitor to upcoming PAM4-based direct-detect optical modules for shorter-reach data center interconnect applications.

"Acacia's CFP2-DCO can address a wide range of networking applications in a compact form factor," said Benny Mikkelsen, Acacia Communications founder and CTO, via the press release. "Our team has done a great job to develop this low-power solution, while maintaining high performance. With the Optical Internetworking Forum (OIF) developing a CFP2-DCO Implementation Agreement, the form factor is positioned for wide adoption in the optical networking industry and with support for up to 400 Gbps, the CFP2-DCO form factor can offer network operators a long-term return on investment."

Acacia Communications began sampling the device last year (see "Acacia Communications samples CFP2-DCO with internal coherent DSP"). At least one systems vendor has touted use of CFP2-DCOs in their platforms (see "MRV adds data center interconnect 200G digital muxponders to OptiDriver line via CFP2-DCO optical transceivers").

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