OFC 2023: Accelerating the Evolution of Optical Networking
March 22, 2023
By Tim Doiron
Vice President, Solutions Marketing
OFC 2023 is officially in the record books. The conference and Optica’s 2023 Executive Forum were held in San Diego March 5-9. This is the second year that we have been back face to face following the pandemic. The 11,500 attendees and the excitement at this year’s event were particularly noticeable. I kicked off a panel on Monday, March 6 at the Optica Executive Forum titled “What and Where is the Coherent Optical Edge?”. The panel included participants from AT&T, American Tower, KDDI, Acacia/Cisco, and Infinera. With coherent optics moving closer to the edge of the network as an evolution of 10G and 100G direct-detect technology and multiple vendors having recently announced 100G coherent pluggables with lower power and smaller form factors, this was a timely topic. While 100G coherent pluggables are not yet widely deployed at the edge, our panelists were optimistic that adoption will accelerate in coming years.
Julia Larikova and I also presented “Optical Innovations and Their Impact on Network Architectures” in Theatre III on the show floor. With service providers embracing a mix of pluggable and embedded optical engines and with coherent pluggables like Infinera’s QSFP-DD-packaged ICE-X ZR+ achieving 400G deployment distances of 1,800 km in live networks like Arelion’s, we need to rethink today’s rigid domain boundaries among access, metro, long-haul, and even submarine networks. A multi-haul optical line system with mix-and-match sled modularity across Layer 0/1 can help us flatten the network, eliminate artificial boundaries, improve economics, and support a diverse set of wavelengths from many sources. In optical networking at least, the future looks flat and full of aliens.
As OFC contains so many quality papers, presentations, and panels, it is truly difficult for one person’s perspective to do justice to the event. I thus asked my Solutions Marketing colleagues to weigh in with their unique perspectives and give you a sense of what stood out most for them at this year’s event.
Turning Point for Pluggables
This year’s OFC marks a turning point for coherent pluggables. Last year, many service providers expressed interest in them and outlined a plan for deployment. However, operational challenges and supply chain issues have created major headwinds. This year, coherent pluggables took center stage in many speaking sessions, technical papers, and in-booth discussions. Equipment vendors are raising the bar of what role these coherent pluggables can play in the network by enhancing optical performance and adding system-level capabilities. As a matter of fact, two new industry records have been announced about QSFP-DD coherent pluggables providing 400G over long-haul-type distances.
Two more takeaways from OFC are the increased interest in pushing coherent pluggables to the edge to cope with the relentless demand for bandwidth and the opportunity to evolve existing 10G direct-detect links to the coherent era. Discussions centered around the introduction of 100G coherent pluggables and the overlay of high-capacity coherent traffic over existing PON infrastructure to deliver next-generation business services while maximizing ROI. As coherent pluggables get a wider application scope, their host devices are becoming more diverse. Multi-host point-to-multipoint and high-performance point-to-point demos, in addition to interoperability forums, took the stage at OFC 2023, shedding some light on how management can be performed across a wide set of host devices to take full advantage of the all the new optical functions and capabilities supported in coherent pluggables. To conclude, for me, coherent pluggables are evolving from providing simple point-to-point connectivity to become and operate as an “optical network element” inside a wide variety of host devices in a broad set of applications. Exciting times indeed.
To Shannon and Beyond
I attended a very interesting workshop, “Is It Really Game Over for the Quest to Approach Fiber Capacity Limits?”, that discussed how much closer we can get to the Shannon limit in terms of improving spectral efficiency. The consensus appeared to be that there was scope to improve spectral efficiency by 10% to 30%, theoretically even 40%, though ~20% appeared to be a more realistic target given processing and power consumption constraints. And while 20% better spectral efficiency would be a great technical achievement and no doubt very valuable for existing fiber deployments, Jeff Rahn from Meta pointed out that this was equal to approximately six months of bandwidth growth. So how do we scale capacity in the future beyond this ~20% spectral efficiency boost?
Well, the conference covered many short-term, medium-term, and long-term options. Short-term approaches included expanding the spectrum with C+L (9.6 THz) and Super C + Super L (12 THz). New integrated C+L wavelength-selective switches and amplifiers (with multiple EDFAs or semiconductor optical amplifier technology) provide one approach to driving down the cost of C+L. Another short-term option is space-division multiplexing (SDM), which was covered in multiple presentations and increases the number of fiber pairs in the subsea cable. One new idea I heard was using quad WSS and even octal WSS as a cost-effective ROADM solution for multiple parallel fibers in terrestrial networks. Uncoupled multi-core fibers able to leverage existing transponder technology are a medium-term option. Longer-term options include coupled multi-core fibers, which will require complicated MIMO-based processing in the transponder DSP, and hollow-core fibers, which might provide the ultimate solution with no nonlinearities and ultra-low loss, enabling a massive leap in spectral efficiency from higher-order modulation.
PON Evolved and for Business
OFC always draws out the latest and greatest at the high end of the optical networking capacity spectrum. This year there was a lot of focus on C+L-band capabilities, which are now finally being deployed in operator networks. Multiple announcements, including Infinera’s announcement of ICE7, highlighted the next generation in coherent optical engines that is emerging with support for 1.2/1.6 Tb/s per wavelength and their respective DSP timelines for commercialization. In addition, this year there was also a lot of focus at the opposite end of the spectrum with fiber-to-the-home/-business/-cell tower deployments over PON infrastructure.
The underlying PON technology continues to evolve beyond XGS-PON, with many vendors outlining their next steps along the PON journey to 25G-PON and even an announcement of an early demonstration of 50G-PON. One area that really resonated well with network operators that I spoke to was the challenge of delivering high-capacity enterprise services over existing single-fiber PON infrastructure that exceed the capacity of existing PON technology or that future 25G/50G PON technology will be able to deliver. In the Infinera ICE-X point-to-multipoint booth demo, we also demonstrated subcarrier-based coherent optics running over a PON network to deliver exactly this kind of service. DZS supplied a PON network carrying residential GPON and XGS-PON traffic. The demo added a high-capacity 100G service over this single-fiber infrastructure seamlessly. Residential PON and point-to-multipoint coherent wavelengths coexisted in the demonstration, highlighting the complementary approach that enables service providers to support a range of residential and small and medium enterprise (SME) services, including mobile transport over a common, shared PON infrastructure. This application resonates with network operators and looks like a very likely early use case for point-to-multipoint architectures.
Put That Safety Margin to Use!
As many of you already know, I am always on the lookout for interesting network automation concepts and applications. For reasons related to my past professional experience, I am particularly curious about applications that challenge the common practice of stacking optical “safety” margins when planning and provisioning a new wavelength to account for worst-case scenarios and cases where good optical performance characterization is lacking.
Unused safety margins could and should be converted into higher network capacity! I have seen in the past a few proofs of concept and tools where a management system or controller is able to estimate real-time channel margins, combining performance monitoring data from across the network, including coherent receivers’ measurements as well as per-channel power values from the optical line system network elements. But, considering the current trend toward open optical networking, wouldn’t it be awesome if a transponder alone, independently of the line system, could assess quality of transmission accurately and in real time, identify the highest feasible wavelength capacity given the actual link conditions, and predict its operating margin?
This year, at the OFC Demo Zone, I saw this type of self-calibrating transponders working live. If you didn’t have the chance to check it out at the event but agree this is a great idea, you can still learn about it here.
Eliminating Barriers with Multi-haul Optical Line Systems
Picking up on Tim’s multi-haul OLS comments at the beginning of this blog, I spent the majority of my time at this year’s OFC demonstrating live our GX multi-haul line system carrying wavelengths from a variety of sources, including legacy 100G QPSK, new 400G pluggable XR and 400G open ZR+ wavelengths, and the most advanced 800G PCS 64QAM-modulated wavelengths all on the same network and fiber. We also showcased GOSNR-based link control and automated power balancing. Further, we utilized streaming telemetry and a third-party open-source tool, Telegraf, to visualize the live performance data. The GX multi-haul line system included 20D ROADMs and both colorless and colorless-directionless-contentionless (CDC) add/drop functionality, which marks a major evolution step for the Infinera GX portfolio. With Super C and Super L spectrum support designed in, GX offers a path beyond 100 Tb/s per fiber, delivering maximum performance and fiber capacity.
As you just read, OFC 2023 was rich with new product announcements and leading-edge technology demonstrations. If you would like to discuss any of these topics further, feel free to reach out to our Infinera sales colleagues or to myself directly. We all look forward to seeing you at another trade show or webinar in 2023.
Safe travels everyone.