Pluggable Amplifiers for DCI Line-Systems

On a related topic and using the same rationale, we are working with industry partners on standardizing a simple and DCI pluggable point-to-point line-system, with the EDFAs integrated into QSFP. This would be optimized for around 100 km and 8-16 channels of 400G-ZR wavelengths, for which most existing solutions are over-capable in the context of IPoDWDM applications. The short target distances also have a strong positive correlation to scenarios in which fiber is plentiful, capacity requirements limited, and thus where spectral efficiency less of a concern. Traditional line-systems for this application come with all the before-mentioned caveats mentioned about discrete transponders in section 2., including surplus components (CPUs, power feeds, fans/cooling), intra-device redundancy, mgmt. interfaces and software, monitoring, and front-heavy deployments from a CAPEX perspective. Because these pluggable EDFAs will be implemented in a QSFP-DD, they will also backward compatible to QSFP28 and as such (as opposed to existing solutions):

• Can be plugged into any QSFP cage, offering an opportunity for uniformity and in some (QSFP28) save on forwarding silicon
• For the few companies deploying OSFP cages, a passive adapter can be used for compatibility
• Reuses most existing standards for control and monitoring

In addition, it provides a much-needed reset of traditional vendor commercial models, fosters ease-of-adoption of 400G-ZR and is very straightforward operationally.

Although embedding EDFAs into pluggable optics for booster and pre-amplification functionality is nothing new, it’s becoming much more relevant when there’s finally a high-volume use-case for IPoDWDM in many SPs access and aggregation domains.

This is especially true when considering the reach of direct-detect technologies becomes ever-shorter as data rates go up beyond 400G. It can potentially also address inter-working with brownfield deployments when 400G-ZR wavelengths launching at -10 dB have to co-exist with traditional ones. Consider Figure 5 and an illustrative subset of <120 km circuits and their respective capacity in Mbps:

Figure 5 – Distance to Capacity relationship in sample metro

In this subset, there is no circuit larger than 1.8 Tbps. If assuming a 16-channel system of 400G-ZR yielding a total of 6.4 Tbps, the spectrum utilization would be just 28%.

The other aspect when taking into account the beforementioned radical cost structure changes is that for these (relatively) low-capacity and short-distance deployments primarily for access and aggregation, a traditional (albeit for simple point-to-point) OLS may now very well represent the most significant part of CAPEX (and OPEX, respectively) for new deployments.

Having a uniform solution to adress scenarios for brownfield inter-working, distances >40 km and/or muxing/demuxing of multiple 400G-ZR then becomes very powerful and presents the very first potential high-volume deployment for (Q)SFP pluggable EDFAs across network operators worldwide. Especially for scenarios within the teal dotted box of Figure 7, which have previously had a relatively high deployment cost.

Conclusions

In this subset, there is no circuit larger than 1.8 Tbps. If assuming a 16-channel system of 400G-ZR yielding a total of 6.4 Tbps, the spectrum utilization would be just 28%.

The other aspect when taking into account the beforementioned radical cost structure changes is that for these (relatively) low-capacity and short-distance deployments primarily for access and aggregation, a traditional (albeit for simple point-to-point) OLS may now very well represent the most significant part of CAPEX (and OPEX, respectively) for new deployments.

Having a uniform solution to adress scenarios for brownfield inter-working, distances >40 km and/or muxing/demuxing of multiple 400G-ZR then becomes very powerful and presents the very first potential high-volume deployment for (Q)SFP pluggable EDFAs across network operators worldwide. Especially for scenarios within the teal dotted box of Figure 7, which have previously had a relatively high deployment cost.

• Minimize time spent in sourcing and validation by automating operations and reducing complexity to onboard new technologies faster as they become available
• Map depreciation times to the (new) economically viable lifetime of equipment
• Reuses most existing standards for control and monitoring

Open and partially disaggregated optical networks provide a framework for commissioning and operating alien wavelengths uniformly as the default deployment paradigm.

Standards-based 400G DWDM pluggable optics put directly into high-scale routing systems bring much-needed fluency to vendor competition in addition to redefining network economics, operational simplicity, and architectures.

For many network operators, this requires breaking down the cultural, process, planning, and organizational barriers that have kept the IP and Optical domains apart and as such often lead to sub-optimal decisions. With the emergence of disruptive technology innovations discussed in this post, there have never been stronger incentives to finally get it right.