Accounts for ~25% of Total Coherent Ports Deployed Worldwide

Generational advancements in transistor density have led to extraordinarily powerful devices, from smart phones to high-capacity switches and routers. Coherent digital signal processors (DSPs), the “brains” inside coherent optical modules, have benefitted from Moore’s law, enabling tremendous optical transmission capacity and capabilities that were not possible a decade ago.

Adoption of coherent technology has increased dramatically, driven by rising bandwidth demand and technological advancements in DSPs, silicon photonics (SiP), and integration. Coherent DSP technology will be critical for supporting higher speeds in next generation networks. In anticipation of this, Cisco has put together a best-in-class development organization to address this technology requirement. Combining Acacia DSPs with Cisco’s internally developed designs, more than 650,000 coherent ports have been shipped, which accounts for approximately 25 percent of the total coherent ports deployed worldwide based on Cignal AI market reports.

Coherent technology was first adopted in long-haul applications, but as data rates increase, coherent is being utilized in higher volume edge and metro interfaces that are more sensitive to power consumption. Over time, these shorter reach interfaces are contributing an increasing share of the total coherent ports deployed.

Coherent DSPs are generally designed to support two kinds of implementations: embedded modules that are mounted onto a line card or inside a chassis, and those used in pluggable modules that are front-panel accessible. Cisco’s broad range of these DSP applications in both router platforms and optical transport systems provide us with a deep understanding of the requirements for both embedded and pluggable architectures. The combined teams have developed a total of six DSPs for embedded and three DSP generations for pluggable modules, bringing a wealth of in-house design expertise to the table.

Flexible Multi-Haul Solutions

Embedded modules using high-performance DSPs with sophisticated algorithms address a range of applications including high-capacity links between data center sites and metro and long-haul networks, as well as inter-continental submarine transmission. For that reason, embedded modules are described as multi-haul solutions and provide additional operational benefits of being a single platform deployed in multiple network applications.

Embedded coherent modules, such as Acacia’s 1.2T AC1200 module using Acacia’s Pico DSP, is an example of a multi-haul solution that has been deployed by network operators in metro, long-haul, and subsea networks. For service providers that have a range of applications and reach requirements, this flexible solution allows for CapEx and OpEx savings since deploying and managing multiple application-optimized platforms (e.g., metro-optimized plus long-haul-optimized platforms) are no longer necessary. For example, Australia’s Academic and Research Network (AARNet) was able to take advantage of Cisco’s NCS 1004 multi-haul capabilities by deploying the same platform in their metro, regional, and submarine networks.

Routed Optical Networking

In the case of pluggable coherent modules, such as the Quad Small Form-factor Pluggable-Double Density (QSFP-DD), the key attributes are compact size and low power, with high volume capabilities. A new generation of recently introduced coherent pluggable 400Gbps modules, such as the 400ZR and OpenZR+ modules, plug directly into switches and routers. This enables operators to imagine different and transformational network architectures. For example, the Cisco Routed Optical Network solution is enabled by these 400G coherent pluggables, providing a simplified architecture compared to traditional optical networks running IP traffic.

The industry introduction of 400G pluggables reflects a major market inflection point where 400G DSPs begin to accelerate in market adoption because they are capable of being designed into multiple form factors, and by multiple vendors.

Although pluggable coherent has been available since the introduction of Acacia’s 100G CFP module in 2014, 400G coherent pluggables are expected to further introduce the adoption of pluggable coherent. In fact, industry analyst LightCounting is forecasting that by 2025 the deployment of pluggable coherent ports at 100G and above will increase by over 200 percent.

In order to support growing bandwidth demand, continued innovations will be needed. The momentum for advancements in the coherent ecosystem of DSPs, SiP, and integration technology will continue to evolve to meet customer needs, leveraging reductions in CMOS node sizes and increases in silicon photonics modulation speeds.

Learn More – Cisco at OFC

Coherent DSPs have already played a major role in driving increased optical transmission and new capabilities in a wide range of applications – and this will continue in the future. As evidenced by the sheer volume of combined Cisco/Acacia coherent DSP ports that have shipped to date, it is clear this technology is capable of enabling network providers to meet the growing global demand for more bandwidth in a simple and cost effective way. This will be accomplished through our continued advancements in DSPs, silicon photonics and integration as well as innovative designs. Learn more at our virtual OFC Booth.


Bill Gartner

Senior Vice President/GM

Optical Systems & Optics Group