SERGE MELLE SUPER COHERENT OPTICS
to increase further due to data center virtualisation, the shift from on-premise to cloud-delivered services, and the growth of AI and ML workloads that drastically increase compute and connectivity requirements. One option used for optical DCI is to use pluggable coherent optics such as 400ZR that can be directly equipped in 400GE router ports. Consuming 20 Watts or less of power and enabling optical DCI up to 80- 100km, they reduce power consumption and thus impact the OpEx part of network TCO. Another solution for metro DCI is to use super-coherent optics, which can double fibre capacity compared to 400ZR. For DC operators who either lease fibres or have limited fibre deployed, but must nevertheless connect large capacities between data centers, high-performance coherent optics used can help extend their DCI capacity before additional CapEx costs for more fibres are incurred. The benefit of sixth-generation, performance-optimised optics in this case can be seen by comparing their capacity- reach capabilities. For example, they can transmit up to 1.2Tbps of data over 100km using only 150 GigaHertz (GHz) of fibre spectrum, while 400ZR optics transmit only 400Gbps over the same distance using up to 100GHz of spectrum. Pairing two 1.2Tbps super-coherent optics into a single virtual 2.4Tbps channel can also enable efficient transport of 3 x 800GE services over only 300GHz of spectrum. The performance-optimised super- coherent optics can thus also enable the seamless upgrade of routers from 400GE to 800GE ports without changes to the transport solution, helping operators reduce router power per bit by 75% by moving to 800GE. Thus, the latest high-performance optics can double the capacity of DCI links compared to 400ZR and 800ZR optics (see Figure 1) and help reduce both CapEx and OpEx. MINIMISING TCO IN REGIONAL AND LONG-HAUL NETWORKS For larger regional and long-haul networks that span countries and continents, or when optical DCI
Figure 1: Performance-optimized coherent optics double metro DCI capacity compared to 400ZR pluggable optics, deferring capacity exhaust for fiber-constrained operators. Image: Nokia Networks
up to 50%, enabling important CapEx reductions (see Figure 2). Reducing the number of coherent optics needed in the network also enables significant progress toward meeting sustainability objectives. Leveraging Moore’s Law, super-coherent optics reduce the power-per-bit by up to 40% versus prior generations. Combined with reducing the number of optics needed for a given network capacity, network operators can reduce total network power consumption by up to 60% (see Figure 2-b) to further reduce network TCO. In summary, the latest generation of performance-optimised coherent optics will usher in a range of transformational benefits to impact optical network operators’ evolution requirements. Providing the scale and performance needed to efficiently transport next- generation services such as 800GE, while
connections extend beyond a few hundred kilometers, performance- optimised coherent optics provide scalable connectivity across hundreds to thousands of kilometers. With IP core networks upgrading to 800GE interfaces to enable greater scale and lower router power consumption, the optical transport layer must correspondingly provide an efficient means for 800Gbps transport across all distances, while helping to lower TCO for the optical network. In this context, a key attribute of sixth- generation, performance-optimised coherent optics is the ability to support 800Gbps interconnections over practically any distance. Compared to the prior generations of coherent optics powered by 7nm DSPs operating at speeds of 90-100GBaud, sixth-generation coherent solutions provide three times the transmission reach over a single wavelength, over distances of 2000km or more. Thus, 800GE transport becomes possible over long spans without the need for regeneration or splitting services across two wavelengths operating at lower speeds, both of which increase CapEx, space and power. The latest performance-optimised coherent optics can reduce the number of coherent optics needed in long-haul networks by
also reducing network power consumption, provides network
operators with a powerful tool for reducing network TCO.
Serge Melle, Director, Optical Networks Product Marketing, Nokia Optical Networks Serge Melle joined Nokia in
2019, having previously led North American sales enablement for IP-optical networks. Prior to joining Nokia, Serge worked at Infinera in product and solutions marketing, and business development. Prior to that worked at Nortel Networks, where was responsible for solutions marketing and business development, and at Pirelli Telecom Systems, where he was involved in the implementation of the industry’s first WDM network deployments. Extensively published, he holds a BSc in physics from Concordia University, Montréal, and an MASc in applied physics from the University of Toronto.
Figure 2: Sixth-generation super-coherent optics enable lower network TCO by (a) reducing the number of optics needed in the network, and (b) lowering total network power consumption. Image: Nokia Networks
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ISSUE 34 | Q3 2023
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