JOHN WILLIAMSON 800G AND BEYOND
latest silicon capabilities, are becoming available, and they will operate at much higher speeds of 130 Gbaud or higher. He reasons that the big enabler this provides is much better optical transmission performance at 800G, thus allowing transport of an 800GE service over a single wavelength at distances of 2,000km in long-haul networks, or across trans- oceanic cable systems. “This not only reduces the number of coherent optics needed in a typical network by up to 50% than current coherent solutions, saving network operators CapEx, this now opens the ability of IP networks to scale to 800GE connections across all applications – metro, regional and long-haul core networks – using one ubiquitous solution,” he states. Maher’s take on increasing 800G’s reach has several elements. One is vertical integration by the system producer. He argues that when you go up to very high symbol rates, say 100 or 150 Gbaud, it becomes more and more critical that you make everything in-house. “There’s a delicate interplay between all the different sub components that go into making a product, and small differences can have significant impacts on performance,” he contends. He maintains that owning your own InP semiconductor fab, in-house DSP design capabilities, and advanced packaging facility, enables significantly greater control over innovation and supply chains. In addition to enabling innovation, Maher declares that full vertical integration also enables the holistic co-design of the complete optical engine, reducing inefficiencies typically introduced when integrating subcomponents from different sources. BUT 400G MARCHES ON Notwithstanding the growing appetite for 800G adoption, the demand for 400G technology remains very strong in various areas of application. Martin Vallo, Ph.D., Senior Analyst Photonics, within the Photonics and Sensing Division at Yole Intelligence, calculates that total 400G Ethernet optics shipments through 2022 were more than five million ports, and says the forecast for 2023 is another seven
million, and more than 10 million for 2024. “So the 400G optics module market will be growing for at least the next three years.” He is also of the opinion here that the transition to 800G modules will be smooth as they use the same 100G single lambda optics technology. “Additionally, we will see 800G modules with 200G single lambda that will start in 2025 and reach mass production in 2026,” he estimates. COHERENT ADHERENTS Coherent optics are a key enabling part of the 800G story, and there are expectations that the progress of this technology could be unstoppable. “We are definitely seeing a surge in demand for coherent optical solutions,” says Maher. “While it began primarily as a solution for long-haul and subsea networks, as bandwidth continues to grow, the need for coherent solutions is driving closer and closer to the network edge and ultimately will likely be used even inside data centres.” What’s more, in this coherent-intensive environment Maher suggests the days of intensity modulation and direct detection (IM/DD) could be numbered. “There’s only a couple of places where intensity modulation and direct detection are still used. And one’s intra data centre, with LR pluggables,” he remarks. Maher also mentions the current debate about the new 10km 800 LR standard and the 800 ZR 80 to 120km standards, which the industry is trying to move towards, and the question about whether they should be IM/DD or coherent. He believes there’s a good chance that data centre applications will ultimately be better served by coherent solutions. Maher also sees IM/DD under threat in access edge applications. “And you know, bandwidth only goes in one direction – up. Because IM/DD solutions have a much lower capacity ceiling than coherent solutions, links that are served by IM/ DD today will, at some point, need to be upgraded to coherent.”
high-speed optical networking innovation. With embedded 800G now available as commercial products, Maher is convinced that 800G coherent pluggables are next up for the big time. According to Vallo, the implementation of 800G coherent pluggables achieving 128 Gbaud nominal symbol rate requires advances in system integration of DSP and optics, as well as efficient DSP algorithms to facilitate high signal integrity in a low- power manner. “We expect to sample 800G-16QAM DSP later this year and have products next year,” reports Vallo. Among other cutting-edge developments in the 800G landscape, Vallo instances DML and QDL technologies, Thin-Film Lithium Niobate (TFLN) integrated photonics, and 800G PAM4 platforms powered by 5nm CMOS. This last, says Vallo, offers more than 25% system-level power efficiency savings compared to the previous 7nm generation, while reducing latency and system implementation complexity. For her part, Xenos anticipates the market delivering fibre-optic technologies that enable 1.6 and 3.2Tbps speeds in the coming years. Meantime, Melle looking at metro distances where sixth-generation super-coherent optics can operate at 1.2Tbps per wavelength, says some solutions are able to pair two wavelengths into a 2.4Tbps channel and transport up to three 800GE services using only a single line-card.
POWER PLAY For technical, economic and
environmental reasons, lowering power requirements is essential for present and future 800G networking. Melle acknowledges that reducing network power consumption has become imperative for all operators, and reducing “power per bit” as networks scale is a must in order to meet global sustainability targets. “In this context sixth-generation super-coherent optics can reduce total network power consumption by up to 60% for 800GE service transport, and thus will make a significant impact in allowing network operators to scale in a sustainable manner” he states.
COMING TO A NETWORK NEAR YOU? No one thinks contemporary 800G technology is the end of the line for
Helen Xenos Senior Director, Portfolio Marketing, Ciena
Robert Maher CTO, Infinera
Serge Melle Director, IP-Optical Product Marketing, Nokia
Martin Vallo Senior Analyst Photonics, Yole Intelligence
ISSUE 32 | Q1 2023
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