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Optical/IP Networks

The next frontier for coherent pluggable optics: 100G

The coherent pluggable optics revolution that began with 400ZR continues to advance. Most of the "beyond 400G" discussion to date has centered on coherent 800G, the next-generation higher bit rate option. But the newest development is an evolution "downmarket" to 100G rates.

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 first installment of four blogs highlighting the key findings from the 2022 Coherent Optics Survey. It focuses on trends in 100G coherent pluggables.

The new optical edge

Developing the right edge strategy is top of mind for most operators today. For the optical edge, 400 Gbit/s may be too much capacity and cost for many applications. Yet, innovations pioneered at 400G—including digital coherent optics (DCO) housed in client-sized form factors—hold strong appeal. The industry labels these new optics 100G ZR, and characteristics include QSFP28 form factors and 5 watt power consumption. Separately, the Open XR Forum was formed in 2021 to address access and edge applications with coherent pluggables that operate at 100/400G.

Heavy Reading believes it is these new coherent 100G technologies and form factors that are driving operator interest in the edge. And the interest level is very high. More than three-quarters of operators surveyed believe that 100G coherent pluggable optics are at least "important" for their edge and access evolution strategy, meaning that coherent 100G will be used extensively in these segments. For one-quarter of the survey group (25% of respondents), coherent 100G is "critical," meaning that almost all 100G deployments will be based on coherent pluggables. Just 1% of respondents see coherent 100G playing no role at the edge.

How important are 100G coherent pluggable optics for your edge/access evolution strategy?

 (Source: Heavy Reading, 2022)

(Source: Heavy Reading, 2022)

Primary use cases

Delving deeper into the edge, Heavy Reading asked operators to identify the most common use cases for 100G coherent pluggables. Topping the list for the global audience are 5G mobile backhaul/midhaul (selected by 40% of respondents), 5G fronthaul (selected by 37%) and enterprise connectivity (at 36%). 5G is in the midst of the mass rollout phase globally. 5G and edge strategies are repeatedly cited in Heavy Reading surveys as operators' top priorities, and the two are tightly linked.

Extending geographic reach is an inherent benefit of coherent technology compared to direct detection. In the global results, this use case is important but not primary. However, filtering results for US respondents only, extending geographic reach is the top use case – followed closely by mobile backhaul. Regions with large geographies (like the US) will gravitate to coherent 100G for the reach it delivers.

When considering 100G coherent pluggables, what do you see as the most common use cases?

 (Source: Heavy Reading, 2022)

(Source: Heavy Reading, 2022)

Form factors and power requirements

Lastly, to better understand network operator requirements, Heavy Reading asked respondents about several technical parameters for 100G coherent pluggables, including form factor preferences, power consumption and output power metrics.

Across the three metrics, the most clarity is shown in the form factor. At 47%, nearly half plan to use the QSFP28 form factor, while a much smaller number prefer QSFP-DD (at 31%). Still, 17% report that they "don't know," a high percentage indicating that many operators are in the early education phase.

For maximum power consumption, an even higher share of operators (25% of respondents) has not yet formed an opinion, and the results are similar for minimum output power (22% reporting "don't know"). While the data shows a mix of preferences for both power consumption and output power, it is hard to align them with each other. For example, QSFP28 modules will not support the high output power that the majority of respondents anticipate.

Heavy Reading believes the biggest takeaway is that network operators have not formed solid preferences. There are two possible explanations:

  • It is too early in the education phase for operators to have built out these requirements internally.
  • Operators will instead focus on higher level requirements (e.g., capacity, compatibility and distance) and leave the granular specifications to the systems and modules suppliers to sort out.

What are the key parameters of your planned 100G coherent pluggable solution?

 (Source: Heavy Reading, 2022)

(Source: Heavy Reading, 2022)

Interest in 100G coherent pluggable optics for edge/access applications is clear, and most operators have identified key use cases for their deployment. This is all good news. But, like most early-stage technologies, an education phase will be required and suppliers and operators must align on requirements, timelines and expectations.

Looking for more information?

Coherent Optics: 100G, 400G and Beyond

This blog is sponsored by Effect Photonics.

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