As coherent optical technology evolves, it introduces new opportunities for operators but also new requirements for addressing those opportunities. Among the opportunities, operators are eyeing 400G transport services for both internal and external applications, as well as pushing coherent optics at 100G data rates down to the metro edge.

To understand the future of high speed coherent optics, Heavy Reading launched the Coherent Optics Market Leadership Program with industry partners Ciena, Effect Photonics, Infinera and Ribbon. The 2022 project was based on a global network operator survey, conducted in August, that attracted 87 qualified responses.

This is the third installment of four blogs highlighting the key findings from the 2022 Coherent Optics Survey. It focuses on 400G transport services, coherent optics requirements and features and primary use cases for 100G coherent pluggables.

400G transport services

Nearly half of operator respondents in Heavy Reading's survey will have deployed 400G transport services in their network between now and the end of 2023. But what are their top motivations for offering 400G transport services? Globally, the top driver for 400G services by far is infrastructure optimization for internal networks. This driver was selected by more than two-thirds of operators surveyed and well ahead of the second choice, standardization of router connections.

The data suggests that, for the global audience of operators, there are not that many customers currently that require full 400Gbit/s connectivity. Yet, there is value in grooming internal traffic up to 400G for greater efficiency and lower costs (e.g., fewer ports, lower cost per bit, etc.).

Beyond internal infrastructure, however, the drivers vary significantly by region, particularly when separating US respondents from their Rest of World (RoW) counterparts. 57% of US operators surveyed identified hyperscalers (or Internet content providers) as a 400G service driver — a strong showing and second only to internal infrastructure in the US. In contrast, just 31% of RoW operators identified Internet content providers as a top driver.

Figure 1: Who or what are your top drivers for 400G wavelength (or optical) transport services? n=42 US, 45 RoW
(Source: Heavy Reading, 2022)

Requirements for 400G and beyond

Looking at 400G transport services in the metro, operators have several options, including delivery via higher performance embedded optics, pluggable coherent optics or a combination of the two. In the case of embedded optics, with a top speed of 800Gbit/s today, multiple 400G services may be delivered over a single 800G wavelength. Alternatively, 400G pluggable optics may be deployed directly into routers to transport client-side traffic. The survey indicates a hybrid environment of coexistence between pluggable and embedded optics within the metro, with over half of respondents expecting a mix of embedded 600/800G and pluggable optics in their metro networks.

But the growing momentum of pluggables is clear, with nearly one-third of operators expecting 100–400G pluggable optics only versus just 15% expecting to standardize on high performance embedded optics.

When choosing coherent pluggables, 61% of respondents selected remote diagnostics as the top advanced feature requirement, followed by auto-tunability (selected by 47%), high launch power (46%) and embedded optical spectrum analysis (40%). Remote diagnostics and auto-tunability both point to the importance of automation in next-generation transport networks. From other Heavy Reading surveys, we know that automation is a critical pillar of operators' next-gen optical networks.

High launch power optics are widely seen as essential for 400G+ pluggables in telecom applications, which are typically brownfield networks with lots of ROADM nodes. Interestingly, when filtering the survey results to include optical specialists only (i.e., those who identify as working in optical transport), higher launch power is the number one requirement, well ahead of remote diagnostics. It is likely that, at this early stage, optical specialists within operators understand the criticality of this particular technical requirement better than their peers.

Figure 3: What advanced coherent DWDM pluggable features or capabilities do you find most beneficial to your network/operations? n=87
(Source: Heavy Reading, 2022)

Use cases for coherent 100G

Beyond 400G, coherent pluggable optics are moving in two directions: to higher data rates at 800G but also lower data rates at 100G. Delving deeper into the newer trend of coherent 100G pluggables at the edge, Heavy Reading asked operators to identify the most common use cases. Topping the list for the global audience are 5G mobile backhaul/midhaul, 5G fronthaul and enterprise connectivity.

However, use case priorities vary significantly based on geographic region, particularly when separating US respondents from their RoW counterparts. For the US, extending geographic reach is the top use case, followed by 5G backhaul/midhaul and enterprise connectivity. For RoW operators, however, extending geographic reach is not a priority use case.

Given the large geography of the US, the importance of 100G coherent technology's greater reach makes sense. Many US operators will be able to upgrade networks to 100G in areas where reach limitations made direct detect 100G technology impossible. This value proposition holds true for other large countries such as Canada or Australia.

Figure 2: When considering 100G coherent pluggables, what do you see as the most common use cases? n=42 US, 45 RoW
(Source: Heavy Reading, 2022)

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This blog is sponsored by Infinera.

— Sterling Perrin, Senior Principal Analyst — Optical Networking & Transport, Heavy Reading