ECOC 2023 industry reflections - Final Part
Gazettabyte has been asking industry figures to reflect on the recent ECOC show in Glasgow. The final instalment emphasises coherent technology with contributions from Adtran, Cignal AI, Infinera, Ciena, and Acacia.
Jörg-Peter Elbers, head of advanced technology at Adtran
The ECOC 2023 conference and show was a great event. The exhibition floor was busy and offered ample networking opportunities. In turn, the conference and the Market Focus sessions provided information on the latest technologies, products, and developments.
One hot topic was coherent 800ZR modems. Several vendors demonstrated coherent 800ZR modules and related components. Importantly, these modules also boast new and improved 400 gigabit-per-second (Gbps) modes. The 120 gigabaud (GBd) symbol rate enables 400-gigabit dual-polarisation quadrature phase shift keying (DP-QPSK) transmission over demanding links and long-haul routes. In turn, the advent of 5nm CMOS digital signal processor (DSP) technology enables lower power DP-16QAM than 400ZR modules.
There is broad agreement that the next step in coherent transmission is a 240GBd symbol rate, paving the way to single-wavelength 1.6 terabit-per-second (Tbps) optical transport.
Meanwhile, the use of coherent optical technology closer to the network edge continues. Several players announced plans to follow Adtran and Coherent and jump on the low-power 100 gigabit-per-second ZR (100ZR) ‘coherent lite’ bandwagon. Whether passive optical networking (PON) systems will adopt coherent technology after 50G-PON sparked lively debate but no definitive conclusions.
The OIF 400ZR+ demonstration showed interoperability between a dozen optical module vendors over metro-regional distances. It also highlighted the crucial role of an intelligent optical line system such as Adtran’s FSP3000 OLS in automating operation and optimising transmission performance.
The post-deadline papers detailed fibre capacity records by combining multiple spectral bands and multiple fibre cores. The line-system discussions on the show floor focused on the practical implications of supporting C-, L-, extended, and combined band solutions for customers and markets.
From workshops to the regular sessions, the application of artificial intelligence (AI) was another prominent theme, with network automation a focus area. Examples show not only how discriminative AI can detect anomalies or analyse failures but also how generative AI can improve the interpretation of textual information and simplify human-machine and intent interfaces. For network engineers, ‘Copilot’-like AI assistance is close.
After ECOC is also before ECOC, so please mark in your calendars September 22-26, 2024. ECOC will celebrate its 50th anniversary next year and will take place in Frankfurt, Germany. As one of the General Chairs of the ECOC 2024 event, and on behalf of the entire organising committee, I look forward to welcoming you!
Andrew Schmitt, founder and directing analyst, Cignal AI
ECOC is a great show, it’s like OFC (the annual optical communications and networking event held in the US) but refined to only the critical elements. Here are my key takeaways.
The most impressive demonstration was 800ZR test boards and modules from Marvell and its partners Coherent and Lumentum. Within eight weeks of the first silicon, Marvell has demos up and running in-house and at its partners. The company has at least a 6-month lead in the 800ZR market, making intelligent tradeoffs to achieve this.
Lumentum showed an 8-QAM mode of operation that allows 800 gigabit transmission within a 100GHz channel spacing, which should be interesting. After the massive success of 400ZR, it’s natural to extrapolate the same success for 800ZR, but the use cases for this technology are substantially different. We also heard updates and broader support for 100ZR.
Linear drive pluggable optics (LPO) was a hot topic, although it was our impression that, while optimism ruled public discussion, scepticism was widely expressed in private. There was more agreement than disagreement with our recent report (see the Active Insight: The Linear Drive Market Opportunity). No one is more confident about LPO than the companies who view this as another opportunity to bid for business at hyperscale operators they don’t currently have.
The 200 gigabit per lane silicon/ physical media device (PMD)/ optics development continues, and it is on track to enable 1.6-terabit optics by 2024. Marvell had a more advanced and mature demo of what they showed behind closed doors at OFC. The advancements here are the real threat to adopting LPO, and people need to realise that LPO is competing with the power specs of 200 gigabits per lane, not 100 gigabits per lane solutions.
Also impressive was the comprehensive engineering effort by Eoptolink to show products that covered 100 gigabit and 200 gigabit per lane solutions, both retimed and linear. The company’s actions show that if you have the engineering resources and capital, rather than pick the winning technology, do everything and let the market decide. Also impressive is the CEO, who understood the demos and the seasoned application engineers. Kudos to keeping engaged with the products!
System vendors had a more significant presence at the show, particularly Ciena and Infinera. It’s unsurprising to see more system vendors since they are increasing investments in pluggables, particularly coherent pluggables.
We had many discussions about our forecasts for IPoDWDM deployment growth. This disruption is something that component vendors are excited about, and hardware OEMs view it as an opportunity to adjust how they deliver value to operators (see the Active Insight: Assessing the Impact of IP-over DWDM).
Lastly, the OIF coordinated 400ZR+ and OpenROADM interoperability testing despite the organisation not being directly involved in those industry agreements. The OIF is a fantastic organisation that gets valuable things done that its members need.
Paul Momtahan, director, solutions marketing, Infinera
ECOC 2023 provided an excellent opportunity to catch the latest trends regarding transponder innovation, coherent pluggables and optical line systems. A bonus was getting to the show without needing a passport.
Transponder innovation topics included coherent digital signal processor (DSP) evolution, novel modulators, and the maximum possible baud rate. DSP sessions included the possibility of offloading DSP functions into the photonic domain to reduce power consumption and latency.
There were also multiple presentations on constellation shaping, including enhanced nonlinear performance, reduced power consumption for probabilistic constellation shaping, and potential uses for geometric shaping.
Novel modulators with very high baud rates, including thin-film lithium niobate, barium titanate, plasmonic, and silicon-organic hybrid, were covered. The need for such modulators is the limited bandwidth potential of silicon photonics modulators, though each face challenges such as integration with silicon photonics and manufacturability.
From the baud rate session, the consensus was that 400GBd symbol rates are probable, up to 500GBd might be possible, but higher rates are unlikely. The critical challenges are the radio frequency (RF) interconnects and the digital-to-analogue and analogue-to-digital converters. However, several presenters wondered whether a multi-wavelength transponder might be more sensible for symbol rates above 200 to 250GBd.
Coherent pluggables were another topic, especially at 800 gigabit. However, one controversial topic was the longevity of coherent pluggables in routers (IPoDWDM). Several presenters argued the current period would pass once router port speeds and coherent port speeds no longer align.
As the coherent optical engines approach the Shannon limit, innovation is shifting towards optical line systems and fibres as alternative way to scale capacity.
Several presentations covered ROADM evolution to 64 degrees and even 128 degrees. A contrasting view is that ROADMs’ days are numbered to be replaced by fibre switches and full spectrum transponders, at least in core networks.
Additional options for scaling capacity included increasing the spectrum of existing bands with super-C and super-L. Lighting different bands, such as the S-band (in addition to C+L bands), is seen as the best candidate, with commercial solutions three to five years away.
Overall, it was a great event, and I look forward to seeing how things evolve by the time of next year’s ECOC show in Frankfurt. (For more, click here)
Helen Xenos, senior director, portfolio marketing, Ciena
This was my third year attending ECOC, and the show never disappoints. I always leave this event excited and energised about what we’ve accomplished as an industry.
Every year seems to bring new applications and considerations for coherent optical technology. This year, ECOC showcased the ever-growing multi-vendor ecosystem for 400-gigabit coherent pluggable transceivers, considerations in the evolution to 800-gigabit pluggables, evolution to coherent PON, quantum-secure coherent networking, and the evolution to 200 gigabaud and beyond. When will coherent technology make it into the data centre? A question still open for debate.
Ciena’s optical engineer wizards were on hand to share specifics about our recently announced 3nm CMOS-based WaveLogic 6 technology, which includes the industry’s first performance-optimised 1.6 teraburs-per-second (Tbps) optics as well as 800-gigabit pluggables.
It was exciting for me to introduce customers, suppliers and research graduates to their first view of 3nm chip performance results and show how these enable the next generation of products. And, of course, Ciena was thrilled that WaveLogic 6 was awarded the Most Innovative Coherent Module Product at the event.
Tom Williams, director of technical marketing at Acacia
From my perspective, while there weren’t as many major product announcements as OFC, several trends and technologies continued to progress, including OIF interoperability, 800ZR/ZR+, linear pluggable optics (LPO) and terabit optics.
The OIF interop demonstration was once again a highlight of the show. The booth was at the entrance to the exhibition and seemed to be packed with people each time I passed by.
OIF has expanded the scope of these demonstrations with each show, and this year was the largest ever. In addition to having the participation of 12 module vendors (with 34 modules), the focus was on the ZR+ operation. What was successfully demonstrated was a single-span 400ZR network and a multi-span network.
As co-chair of the OpenZR+ MSA, I was excited by the great collaboration with OIF. These efforts help to drive the industry forward. Karl Gass is not only the most creatively dressed person at every trade show; he is exceptional at coordinating these activities.
It is clear that linear drive pluggable optics (LPO) works in some situations, but views differ about how widespread its adoption will be and how standardisation should be addressed. I lived through the analogue coherent optics (ACO) experience. ACO was essentially a linear interface for a coherent module where the digital processing happened outside the module. For ACO, it was a DSP on the host board and for LPO it is the switch ASIC. The parameters that need to be specified are similar. There is a precedent for this kind of effort. Hopefully, lessons learned there will be helpful for those driving LPO. I am interested to see how this discussion progresses in the industry as some of the challenges are discussed, such as its current limited interoperability and support for 200 gigabits per lane.
There have been announcements from several companies about performance-optimised coherent optics in what we call Class 3 (symbol rates around 140 gigabaud), which support up to 1.2 terabits on a wavelength. Our CIM 8 module has been used in multiple field trials, demonstrating the performance benefits of these solutions.
Our CIM 8 (Coherent Interconnect Module 8) achieves this performance in a pluggable form factor. The CIM 8 uses the same 3D siliconisation technology we introduced for our 400-gigabit pluggables and enables operators to scale their network capacity in a cost- and power-efficient way.
ECOC 2023 industry reflections - Part 3
Gazettabyte is asking industry figures for their thoughts after attending the recent ECOC show in Glasgow. In particular, what developments and trends they noted, what they learned and what, if anything, surprised them. Here are responses from Coherent, Ciena, Marvell, Pilot Photonics, and Broadcom.
Julie Eng, CTO of Coherent
It had been several years since I’d been to ECOC. Because of my background in the industry, with the majority of my career in data communications, I was pleasantly surprised to see that ECOC had transitioned from primarily telecommunications, and largely academic, into more industry participation, a much bigger exhibition, and a focus on datacom and telecom. There were many exciting talks and demos, but I don’t think there were too many surprises.
In datacom, the focus, not surprisingly, was on architectures and implementations to support artificial intelligence (AI). The dramatic growth of AI, the massive computing time, and the network interconnect required to train models are driving innovation in fibre optic transceivers and components.
There was significant discussion about using Ethernet for AI compared to protocols such as InfiniBand and NVLink. For us as a transceiver vendor, the distinction doesn’t have a significant impact as there is little if any, difference in the transceivers we make for Ethernet compared to the transceivers we make for InfiniBand/NVLink. However, the impact on the switch chip market and the broader industry are significant, and it will be interesting to see how this evolves.
Linear pluggable optics (LPO) was a hot topic, as it was at OFC 2023, and multiple companies, including Coherent, demonstrated 100 gigabit-per-lane LPO. The implementation has pros and cons, and we may find ourselves in a split ecosystem, with some customers preferring LPO and others preferring traditional pluggable optics with DSP inside the module. The discussion is now moving to the feasibility of 200 gigabit-per-lane LPO.
Discussion and demonstrations of co-packaged optics also continued, with switch vendors starting to show Ethernet switches with co-packaged optics. Interestingly, the success of LPO may push out the implementation of co-packaged optics, as LPO realizes some of the advantages of co-packaged optics with a much less dramatic architectural change.
One telecom trend was the transition to 800-gigabit digital coherent optical modules, as customers and suppliers plan for and demonstrate the capability to make this next step. There was also significant interest in and discussion about 100G ZR. We demonstrated a new version with 0dBm high optical output power at ECOC 2023 while other companies showed components to support it. This is interesting for cable providers and potentially for data centre interconnect and mobile fronthaul and backhaul.
I was very proud that our 200 gigabit-per-lane InP-based DFB-MZ laser won the 2023 ECOC Exhibition Industry Award for Most Innovative Product in the category of Innovative Photonics Component.
ECOC was a vibrant conference and exhibition, and I was pleased to attend and participate again.
Loudon Blair, senior director, corporate strategy, Ciena
ECOC 2023 in Glasgow gave me an excellent perspective on the future of optical technology. In the exhibition, integrated photonic solutions, high-speed coherent pluggable optical modules, and an array of testing and interoperability solutions were on display.
I was especially impressed by how high-bandwidth optics is being considered beyond traditional networking. Evolving use cases include optical cabling, the radio access network (RAN), broadband access, data centre fabrics, and quantum solutions. The role of optical connectivity is expanding.
In the conference, questions and conversations revolved around how we solve challenges created by the expanding use cases. How do we accommodate continued exponential traffic growth on our fibre infrastructure? Coherent optics supports 1.6Tbps today. How many more generations of coherent can we build before we move on to a different paradigm? How do we maximize density and continue to minimize cost and power? How do we solve the power consumption problem? How do we address the evolving needs of data centre fabrics in support of AI and machine learning? What is the role of optical switching in future architectures? How can we enhance the optical layer to secure our information traversing the network?
As I revisited my home city and stood on the banks of the river Clyde – at a location once the shipbuilding centre of the world – I remembered visiting my grandfather’s workshop where he built ships’ compasses and clocks out of brass.
It struck me how much the area had changed from my childhood and how modern satellite communications had disrupted the nautical instrumentation industry. In the same place where my grandfather serviced ships’ compasses, the optical industry leaders were now gathering to discuss how advances in optical technology will transform how we communicate.
It is a good time to be in the optical business, and based on the pace of progress witnessed at ECOC, I look forward to visiting San Diego next March for OFC 2024.
Dr Loi Nguyen, executive vice president and general manager of the cloud optics business group, Marvell
What was the biggest story at ECOC? That the story never changes! After 40 years, we’re still collectively trying to meet the insatiable demand for bandwidth while minimizing power, space, heat, and cost. The difference is that the stakes get higher each year.
The public debut of 800G ZR/ZR+ pluggable optics and a merchant coherent DSP marked a key milestone at ECOC 2023. For the first time, small-form-factor coherent optics delivers performance at a fraction of the cost, power, and space compared to traditional transponders. Now, cloud and service providers can deploy a single coherent optics in their metro, regional, and backbone networks without needing a separate transport box. 800 ZR/ZR+ can save billions of dollars for large-scale deployment over the programme’s life.
Another big topic at the show was 800G linear drive pluggable optics (LPO). The multi-vendor live demo at the OIF booth highlighted some of the progress being made. Many hurdles, however, remain. Open standards still need to be developed, which may prove difficult due to the challenges of standardizing analogue interfaces among multiple vendors. Many questions remain about whether LPO can be scaled beyond limited vendor selection and bookend use cases.
Frank Smyth, CTO and founder of Pilot Photonics
ECOC 2023’s location in Glasgow brought me back to the place of my first photonics conference, LEOS 2002, which I attended as a postgrad from Dublin City University. It was great to have the show close to home again, and the proximity to Dublin allowed us to bring most of the Pilot team.
Two things caught my eye. One was 100G ZR. We noted several companies working on their 100G ZR implementations beyond Coherent and Adtran (formerly Adva) who announced the product as a joint development over a year ago.
100G ZR has attracted much interest for scaling and aggregation in the edge network. Its 5W power dissipation is disruptive, and we believe it could find use in other network segments, potentially driving significant volume. Our interest in 100G ZR is in supplying the light source, and we had a working demo of our low linewidth tunable laser and mechanical samples of our nano-iTLA at the booth.
Another topic was carrier and spatial division multiplexing. Brian Smith from Lumentum gave a Market Focus talk on carrier and spatial division multiplexing (CSDM), which Lumentum believes will define the sixth generation of optical networking.
Highlighting the approaching technological limitation on baud rate scaling, the ‘carrier’ part of CSDM refers to interfaces built from multiple closely-spaced wavelengths. We know that several system vendors have products with interfaces based on two wavelengths, but it was interesting to see this from a component/ module vendor.
We argue that comb lasers come into their own when you go beyond two to four or eight wavelengths and offer significant benefits over independent lasers. So CSDM aligns well with Pilot’s vision and roadmap, and our integrated comb laser assembly (iCLA) will add value to this sixth-generation optical networking.
Speaking of comb lasers, I attended an enjoyable workshop on comb lasers on the Sunday before the meetings got too hectic. The title was ‘Frequency Combs for Optical Communications – Hype or Hope’. It was a lively session featuring a technology push team and a market pull team presenting views from academia and industry.
Eric Bernier offered an important observation from HiSilicon. He pointed to a technology gap between what the market needs and what most comb lasers provide regarding power per wavelength, number of wavelengths, and data rate per lane. Pilot Photonics agrees and spotted the same gap several years ago. Our iCLA bridges it, providing a straightforward upgrade path to scaling to multi-wavelength transceivers but with the added benefits that comb lasers bring over independent lasers.
The workshop closed with an audience participation survey in which attendees were asked: Will frequency combs play a major role in short-reach communications? And will they play a major role in long-reach communications?
Unsurprisingly, given an audience interested in comb lasers, the majority’s response to both questions was yes. However, what surprised me was that the short-reach application had a much larger majority on the yes side: 78% to 22%. For long-reach applications the majority was slim: 54% to 46%.
Having looked at this problem for many years, I believe the technology gap mentioned is easier to bridge and delivers greater benefits for long-reach applications than for short-reach, at least in the near term.
Natarajan Ramachandran, director of product marketing, physical layer products division, Broadcom
Retimed pluggables have repeatedly shown resiliency due to their standards-based approach, offering reliable solutions, manufacturing scale, and balancing metrics around latency, cost and power.
At ECOC this year, multiple module vendors demonstrated 800G DR4 and 1.6T DR8 solutions with 200 gigabit-per-lane optics. As the IEEE works towards ratifying the specs around 200 gigabit per lane, one thing was clear at ECOC: the ecosystem – comprising DSP vendors, driver and transimpedence amplifier (TIA) vendors, and VCSEL/EML/silicon photonics vendors – is ready and can deliver.
Several vendors had module demonstrations using 200 gigabit-per-lane DSPs. What also was apparent at ECOC was that the application space and use cases, be it within traditional data centre networks, AI and machine learning clusters and telcom, continue to grow. Multiple technologies will find the space to co-exist.
ECOC 2023 industry reflections
Gazettabyte is asking industry figures for their thoughts after attending the recent ECOC show in Glasgow. In particular, what developments and trends they noted, what they learned and what, if anything, surprised them. Here are the first responses from BT, Huawei, and Teramount.
Andrew Lord, Senior Manager, Optical Networks and Quantum Research at BT
I was hugely privileged to be the Technical Co-Chair of ECOC in Glasgow, Scotland and have been working on the event for over a year. The overriding impression was that the industry is fully functioning again, post-covid, with a bumper crop of submitted papers and a full exhibition. Chairing the conference left little time to indulge in content. I will need to do my regular ECOC using the playback option. But specific themes struck me as interesting.
There were solid sessions and papers around free space optics, including satellite. The activities here are more intense than we would typically see at ECOC. This reflects a growing interest and the specific expertise within the Scottish research community. Similarly, more quantum-related papers demonstrated how quantum is integrating into the mainstream optical industry.
I was impressed by the progress towards 800-gigabit ZR (800ZR) pluggables in the exhibition. This will make for some interesting future design decisions, mainly if these can be used instead of the increasingly ubiquitous 400 gigabit ZR. I am still unclear whether 800-gigabit coherent can hit the required power consumption points for plugging directly into routers. The costs for these plugs, driven by volumes, will have a significant impact.
I also enjoyed a lively and packed rump session debating the invasion of artificial intelligence (AI) into our industry. I believe considerable care is needed, particularly where AI might have a role in network management and optimisation.
Maxim Kuschnerov, Director R&D at Huawei
ECOC usually has fewer major announcements than the OFC show. But ECOC was full of technical progress this time, making the OFC held in March seem a distant memory.
What was already apparent in September at the CIOE in Shenzhen was on full display on the exhibition floor in Glasgow: the linear drive pluggable optics (LPO) trend has swept everyone off their feet. The performance of 100-gigabit native signalling using LPO can not be ignored for single-mode fibre and VCSELs.
Arista gave a technical deep-dive at the Market Focus with a surprising level of detail that went beyond the usual marketing. There was also a complete switch set-up at the Eoptolink booth, and the OIF interop demonstration.
While we must wait for a significant end user to adopt LPO, it begs the question: is this a one-off technological accident or should the industry embrace this trend and have research set its eyes on 200 gigabits per lane? The latter would require a rearchitecting of today’s switches, a more powerful digital signal processor (DSP) and likely a new forward error corrections (FEC) scheme, making the weak legacy KP4 for the 224-gigabit serdes in the IEEE 802.3dj look like a poor choice.
There was less emphasis on Ethernet 1.6 terabits per second (Tb/s) interfaces with 8x200G optical lanes. However, the arrival of a second DSP source with better performance was noted at the show.
The module power of 1.6-terabit DR8 modules showed no significant technological improvement compared with 800Gbps DSP-based modules and looked even more out of place when benchmarking against 800G LPO pluggables. Arista drove home that we can’t continue increasing the power consumption of the modules at the faceplate despite the 50W QSFP-DD1600 announcement.
The same is true for coherent optics.
Although the demonstration of the first 800ZR live modules was technically impressive, the efficiency of the power per bit hardly improved compared to 400ZR, making the 1600ZR project of OIF look like a tremendous technological challenge.
To explain, a symbol rate of 240 gigabaud (GBd) will drive the optics for 1600ZR. Using 240Gbaud with two levels per symbol to create 16QAM over two dimensions is a 400Gbps net rate or 480Gbps gross rate electrical per lane, albeit very short reach. Coherent has four lanes – 2 polarisations & in-phase and quadrature – to deliver four by 400G or 1.6Tbps. This is like what we have now: 200G on the optical side of 1.6T 8x200G PAM4 and 4x200G on 800ZR, while the electrical (longer reach) host still uses 100 gigabits per lane.
The industry will have to analyse which data centre scenarios direct detection will be able to cover with the same analogue-to-digital & digital-to-analogue converters and how deeply coherent could be driven within the data centre.
ECOC also featured optical access evolution. With the 50G FTTx standard completed with components sampling at the show and products shipping next year, the industry has set its eyes on the next generation of very high-speed PON.
There is some initial agreement on the technological choice for 200 gigabits with a dual-lambda non-return to zero (NRZ) signalling. Much of the industry debate was around the use cases. It is unrealistic to assume that private consumers will continue driving bandwidth demand. Therefore, a stronger focus on 6G wireless fronthaul or enterprise seems a likely scenario for point-to-multi-point technology.
Hesham Taha, CEO of Teramount
Co-packaged optics had renewed vigour in ECOC, thanks partly to the recent announcements of leading foundries and other semiconductor vendors collaborating in silicon photonics.
One crucial issue, though, is that scalable fibre assembly remains an unsolved problem that is getting worse due to the challenging requirements of high-performance systems for AI and high-performance computing. These requirements include a denser “shoreline” with a higher fibre count and a denser fibre pitch, and support for an interposer architecture with different photonic integrated component (PIC) geometries.
Despite customers having different requirements for co-packaged optics fibre assembly, detachable fibres now have wide backing. Having fibre ribbons that can be separated from the co-packaged optics packaging process increases manufacturing yield and reliability. It also allows the costly co-packaged optics-based servers/ switches to be serviced in the field ro replace faulty fibre.
Our company, Teramount, had an ECOC demo showing the availability of such a detachable fibre connector for CPO, dubbed Teraverse.
It is increasingly apparent that the solution for a commercially viable fibre assembly on chip lies with a robust manufacturing ecosystem rather than something tackled by any one system vendor. This fabless model has proven itself in semiconductors and must be extended to silicon photonics. This will allow each part of the production chain – IC designers, foundries, and outsourced semiconductor assembly and test (OSAT) players – to focus on what they do best.
ECOC 2023 industry reflections - Part 2
Gazettabyte is asking industry figures for their thoughts after attending the recent ECOC show in Glasgow. In particular, what developments and trends they noted, what they learned and what, if anything, surprised them. Here are more responses from LightCounting, Hyper Photonix, NewPhotonics, and Broadcom.
Vladimir Kozlov, CEO of LightCounting, a market research company
Demand for optical connectivity in data centres has accelerated innovation in the industry. ECOC 2023 offered numerous start-ups and established vendors another opportunity to disclose their latest achievements.
The improved reliability of quantum dot lasers was a pleasant surprise. Alfalume presented the latest quantum dot comb laser developments, including continuous power up to 250 mW with a power conversion efficiency of a quarter (25%) and efficient operation of up to 100oC. Preliminary test data suggests that quantum dot lasers offer superior reliability compared to their quantum well counterparts. It would be great to have a reliable laser source, finally.
Cisco and Intel deserve much credit for bringing silicon photonics-based transceivers to the market, but numerous vendors are entering the race now.
All the leading foundries offer photonic integrated circuits with integrated laser chips. TSMC disclosed its plans to use a 7nm CMOS process to manufacture photonic chips. Recently formed OpenLight offers fully tested photonic integrated circuit designs, which can be produced at several foundries, including Tower Semiconductor.
Many transceiver suppliers have internally designed optical engines. They all plan to reduce the manufacturing cost of silicon photonics-based transceivers, fulfilling the potential of CMOS technology. Competition among suppliers enabled huge reductions in the cost of CMOS-based ICs. Let us see if this works for CMOS-based photonic integrated circuits.
Brad Booth, director of technology and strategy at Hyper Photonix, and a consultant
There was good attendance at ECOC considering some companies continue to limit travel. Linear drive pluggable optics (LPO) is gaining traction but still has hurdles to address. Meanwhile, the 800-gigabit train is pulling into the station with a ZR digital signal processor and client-side modules.
What surprised me at the show? The shift to start-ups. It is reminiscent of the Gigabit Ethernet days.
Yaniv BenHaim, founder & CEO of NewPhotonics
There were some notable trends at ECOC. One is that 800-gigabit optical transceivers are ramping. At least three vendors were giving private demos of 8×100-gigabit DR enabled with the coming availability of 200G EMLs and photodetectors.
The industry is also optimistic about linear drive pluggable optics (LPO), helped by the buzz created by Nvidia, saying it will make the technology available in AI clusters by year-end. Data centres and networking companies are also pushing LPO and evaluating it and will likely announce findings by OFC 2024.
Another upcoming technology, like optical processing, as demonstrated by our company, NewPhotonics, can further advance power savings and range with both traditional optical modules and LPOs. At ECOC, we showed 224 gigabit-per-second (Gbps) optical input-output driving more than 10km of fibre using Intel’s new 224Gbps serialiser-deserialiser (serdes). We also showed NewPhotonics’ optical serdes multiplexing and demultiplexing multiple optical 112Gbps PAM-4 in the optical time domain.
Companies providing coherent technology continue to promote using coherent transceivers in the data centre. We don’t see any reason to do so when PAM-4 non-coherent solutions can cater for data centre needs and also go beyond 10km.
The market is moving forward in using 224 gigabits, which will disrupt optical transceivers and the active optical cable markets. It seems co-packaged optics will be delayed further as the electrical solutions for 50-terabit and 100-terabit switches are already there using electrical serdes.
The optical communication market had no new surprises based on wavelength division multiplexing PAM-4 and 16-QAM. Some ideas exist for replacing the DSP functions with analogue implementations. NewPhotonics is the only company pushing for an all-optical solution instead of an analogue or a digital signal processor solution.
Rajiv Pancholy, director of hyperscale strategy & products, optical systems division at Broadcom
It was evident at ECOC 2023 that the emergence of large networking clusters enabling the connectivity of graphics processing units (GPUs) for recommendation engines and large language models has substantially increased the ratio of photonic to copper links inside data centres. The optics industry has been waiting for an all-to-all connectivity killer app to increase volumes and therefore investment, and that app might have arrived.
Companies demonstrated excellent progress on 200 gigabit per lane optical components. Several companies are sampling 200 gigabit EMLs and plan production in 2024. Several companies also announced plans to release 200 gigabit per lane VCSELs. There was some early demonstration of 200 gigabit per lane silicon photonics, but it is still being determined when the technology will be ready for production.
Lastly, start-ups at the show focused on delivering novel optical interconnect technologies with micro-LEDs, comb lasers, and advanced packaging that reinforces a general trend towards high-density photonic integrated circuits, electrical interconnect simplification, and co-packaging. Though it’s still being determined when these optical technologies will come to market, Broadcom is not the only company working on co-packaged optics. We believe you will need co-packaged optics much sooner than five years from now.
The status of silicon photonics - an ECOC interview
Daryl Inniss and I being interviewed at ECOC by Adtran’s Gareth Spence about the state of silicon photonics.
Click here for the interview.
Optical networking's future
Should the industry do more to support universities undertaking optical networking research? Professor Polina Bayvel thinks so and addressed the issue in her plenary talk at the ECOC conference and exhibition held in Glasgow, Scotland, earlier this month.
In 1994, Bayvel set up the Optical Networks Group at University College London (UCL). Telecom operators and vendors like STC, GPT, and Marconi led optical networking research. However, setting up the UCL’s group proved far-sighted as industry players cut their research budgets or closed.
Universities continue to train researchers, yet firms do not feel a responsibility to contribute to the costs of their training to ensure the flow of talent. One optical systems vendor has hired eight of her team.
In her address, Bayvel outlined how her lab should be compensated. For example, when a club sells a soccer player, the team that developed him should also get part of the fee.
Such income would be welcome, says Bayvel, citing how she has a talented student from Brazil who needs help to fund his university grant. Her lab would also benefit. During a visit, a pile of boxes – state-of-the-art test equipment – had just arrived.
Plenary talk
Bayvel mentioned how the cloud didn’t exist 18 years ago and that what has enabled it is optical networking and Moore’s law. She also tackled how technology will likely evolve in the next 18 years.
Digital data is being created at a remarkable rate, she said. Three exabytes (a billion billion bytes) are being added to the cloud, which holds several zettabytes (1,000 exabytes or ZB) of data. By 2025, data in the cloud will be 275ZB.
The cited stats continued: 6.2 billion kilometres of fibre have been deployed between 2005 and 2023, having 60Zbits of capacity. In comparison, all data satellite systems now deployed offer 100Tb, less than the capacity of one fibre.
Moore’s law has enabled complex coherent digital signal processors (DSPs) that clean up the distortions of an optical signal sent over a fibre. The first coherent DSPs consumed 1W for each gigabit of data sent. Over a decade later, DSPs use 0.1W to send a gigabit.
Data growth will keep driving capacity, says Bayvel. Engineers have had to fight hard to squeeze more capacity using coherent optical technology. Further improvement will come from techniques such as non-linear compensation. One benefit of Moore’s law is that coherent DSPs will be more capable of tasks such as non-linear compensation. For example, Ciena’s latest 3nm CMOS process, the WaveLogic 6e DSP, uses one billion digital logic gates.
Extra wide optical comms
But only so much can be done by the DSP and increasing the symbol rate. The next step will be to ramp the bandwidth by combining a fibre’s O, S, C, L, E and U spectrum bands. New optical devices, such as hybrid amplifiers, will be needed, and pushing transmission distance over these bands will be hard.
“We fought for fractions of a decibel [of signal-to-noise ratio]; surely we’re not going to give up the wavelengths available through this [source of] bandwidth?” said Bayvel.
In his Market Focus talk at ECOC, BT’s Professor Andrew Lord argued the opposite. There will be places where combining the C- and L-bands will make sense, but why bother when spatial division multiplexing fibre deployments in the network are inevitable, he said.
“It is not spatial division multiplexing versus extra wide optical comms; they can co-exist,” said Bayvel.
Bayvel describes work to model the performance of such a large amount of spectrum that has been done in her lab using data collected from the MAREA sub-sea cable. Combining the fibre’s spectral bands – a total of 60 terahertz of spectrum – promises to quadruple the bandwidth currently available. However, this will require more powerful DSPs than are available today.
Another area ripe for development is intelligent optical networking using machine learning.
An ideas lag
Bayvel used her talk to pay tribute to her mentor, Professor John Midwinter.
Midwinter was an optical communications pioneer at BT and then UCL. He headed the team that developed the first trial systems that led to BT becoming the first company in the world to introduce optical fibre communications systems in the network.
In 1983, his last year at BT, Midwinter wrote in the British Telecom Technology Journal that this was the year coherent optical systems would be taken seriously. It took another 20-plus years.
Bayvel noted how many ideas developed in optical research take considerable time before the industry adopts them. “Changes in the network are much slower,” she said. “Operators are conservative and focus on solving today’s problems.”
Another example she cited is Google’s Apollo optical switch being used in its data centres. Bayvel noted that the switch is relatively straightforward, using MEMS technology that has been around for 25 years.
Bayvel used her keynote to attack the telecom regulators.
“It is simply unfair that the infrastructure providers get such a small part of the profits compared to the content providers,” she said. “The regulators have done a terrible job.”
Working at the limit of optical transmission performance
- Expect to see new optical transmission records at the upcoming ECOC 2023 conference.
- Keysight Technologies’ chart plots the record-setting optical transmission systems of recent years.
- The chart reveals optical transmission performance issues and the importance of the high-speed converters between the analogue and digital domains for test equipment and, by implication, for coherent digital signal processors (DSPs).
Engineers keep advancing optical systems to send more data across an optical fibre.
It requires advances in optical and electronic components that can process faster, higher-bandwidth signals, and that includes the most essential electronics part of all: the coherent DSP chip.
Coherent DSPs use state-of-the-art 5nm and 3nm CMOS chip manufacturing processes. The chips support symbol rates from 130-200 gigabaud (GBd). At 200GBd, the coherent DSP’s digital-to-analogue converters (DACs) and analogue-to-digital converters (ADCs) must operate at at least 200 giga samples-per-second (GSps) and likely closer to 250GSps. DACs drive the optical modulator in the optical transmission path while the ADCs are used at the optical receiver to recover the signal.
Spare a thought for the makers of test equipment used in labs that drive such coherent optical transmission systems. The designers must push their equipments’ DACs and ADCs to the limit to generate and sample the waveforms of these prototype next-generation optical transmission systems.
Optical transmission records
The recent history of record-setting optical transmission systems reveals the design challenges of coherent components and how ADC and DAC designs are evolving.
It is helpful to see how test equipment designers tackle ADC and DAC design, given the devices are a critical element of the coherent DSP, and when vendors are reluctant to detail how they achieve 200GBd baud rates using on-chip CMOS-based ADCs and DACs.
Nokia and Keysight Technologies published a post-deadline paper at the ECOC 2022 conference detailing the transmission of a 260GBd single-wavelength signal over 100km of fibre.
The system achieved the high baud rate using a thin-film lithium niobate modulator driven by Keysight’s M8199B arbitrary waveform generator. The M8199B uses a design consisting of two interleaved DACs to generate signals at 260GSps.
A second post-deadline ECOC 2022 paper, published by NTT, detailed the sending of over two terabits-per-second (Tbps) on a single wavelength. This, too, used Keysight’s M8199B arbitrary waveform generator.
The chart above highlights optical transmission records since 2015, plotting the systems’ net bit rate – from 800 gigabits to 2.2 Tbps – against a symbol rate measured in GBd.
As with commercial coherent optical transport systems, the goal is to keep increasing the symbol rate. A higher symbol rate sends more data over the same fibre spans. For example, the 400ZR coherent transmission standard uses a symbol rate of some 60GBd to send a 400Gbps wavelength, while 800ZR doubles the baud rate to some 120GBd to transmit 800Gbps over similar distances.
“With the 1600ZR project just started by the OIF, this trend will likely continue,” says Fabio Pittalá, product planner, broadband and photonic center of excellence at Keysight.
The signal generator test equipment options include the use of different materials – CMOS and silicon germanium – and moving from one DAC to a parallel multiplexed DAC design.
Single DACs
In 2017, Nokia achieved a 1Tbps transmission using a 100GBd symbol rate. Nokia used a Micram 6-bit 100GSps DAC in silicon germanium for the modulation.
For its next advancement in transmission performance, in 2019, Nokia used the same DAC but a faster ADC at the receiver, moving from a Tektronix instrument using a 70GHz ADC to the Keysight UXR oscilloscope with a 110GHz bandwidth ADC. The resulting net bit rate was nearly 1.4 terabits.
Keysight also developed the M8194A arbitrary waveform generator based on a CMOS-based DAC. The higher sampling rate of this arbitrary waveform generator increased the baud rate to 105GBd, but because of the bandwidth limitation, the net bit rate was lower.
The bandwidth of CMOS DACs can be improved but it tops out in the region of 50-60GHz. “It’s very difficult to scale to a higher baud rate using this technology,” says Pittalá. Silicon germanium, by contrast, supports much higher bandwidths but has a higher power consumption.
In 2020, Nokia reached 1.6Tbps at 128GBd using the Micram DAC5, an 8-bit 128GSps DAC based on silicon germanium. A year later, Keysight released the M8199A arbitrary waveform generator. “This was also based on 8-bit silicon germanium DACs operating at 128GSps, but the signal-to-noise ratio was greatly improved, allowing to generate higher-order quadrature amplitude modulation formats with more than sixteen levels,” says Pittalá.
This arbitrary waveform generator was used in systems that, coupled with advanced equalisation schemes, pushed the net bit rate to almost 2Tbps.
Going parallel
For the subsequent advances in baud rate, parallel DAC designs, multiplexing two or more DACs together, were implemented by different research labs.
In 2015, NTT multiplexed two DACs that advanced the symbol rate from 105GBd to 120GBd. In 2019, NTT moved to a different type of multiplexer, which, used with the same DAC, increased the baud rate to around 170GBd. Nokia also demonstrated a multiplexed design concept, which, together with a novel thin-film lithium niobate modulator, extended the symbol rate to 200GBd, achieving a 1.6Tbps net bit rate.
Last year, Keysight introduced its latest arbitrary waveform generator, the M8199B. The design also adopted a multiplexed DAC design.
Multiplexing two DACs. SR refers to sample rate, BW refers to bandwidth. Source: Keysight.
“There are two 128GSps 8-bit silicon germanium DACs that are time-interleaved to get a higher speed signal per dimension,” says Pittalá. If the two DACs are shifted in time and added together, the result is a higher sampling rate overall. However, Pittalá points out that while the sample rate is effectively doubled, the overall bandwidth is defined by the individual DACs (see diagram above).
Pittalá also mentions another technique, based on active clocking, that does increase the bandwidth of the system. The multiplexer is clocked and acts like a fast switch between the two DAC channels. “In principle, you can double the bandwidth, ” he says. (See diagram below.)
The Keysight’s M8199B’s improved performance, combined with advances in components such as NTT’s 130GHz indium phosphide amplifier, resulted in over 2Tbps transmission, as detailed in the ECOC 2022 paper. As the baud rate was increased, the modulation scheme used and the net bit rate decreased. (Shown by the red dots on the chart).
In parallel, Keysight worked with Nokia, which used a thin-film lithium niobate modulator for their set-up, a different modulator to NTT’s. The test equipment directly drove the thin-film modulator; no external modulator driver was needed. The system was operated as high as 260GBd, achieving a net bit rate of 800Gbps.
Pittalà notes that while the NTT system differs from Nokia’s, Nokia’s two red points on the extreme right of the chart continue the trajectory of NTT’s six red points as the baud rate increases.
OFC’23 O-band record
The post-deadline papers at the OFC 2023 conference earlier this year did not improve the transmission performances of the ECOC papers.
A post-deadline paper published at OFC 2023 showed a record of coherent transmission in the O-Band. Working with Keysight, McGill University showed 1.6Tbps coherent transmission over 10km using a thin-film lithium niobate modulator. The system operated at 167GBd, used a 64-QAM modulation scheme, and used the Keysight M8199B.
Pittalà expects that at ECOC 2023, to be held in Glasgow in October, new record-breaking transmissions will be announced.
His chart will need updating.
Further information
Thin-film lithium niobate modulators, click here
ECOC '22 Reflections - Part 3
Gazettabyte is asking industry and academic figures for their thoughts after attending ECOC 2022, held in Basel, Switzerland. In particular, what developments and trends they noted, what they learned, and what, if anything, surprised them.
In Part 3, BT’s Professor Andrew Lord, Scintil Photonics’ Sylvie Menezo, Intel’s Scott Schube, and Quintessent’s Alan Liu share their thoughts.
Professor Andrew Lord, Senior Manager of Optical Networks Research, BT
There was strong attendance and a real buzz about this year’s show. It was great to meet face-to-face with fellow researchers and learn about the exciting innovations across the optical communications industry.
The clear standouts of the conference were photonic integrated circuits (PICs) and ZR+ optics.
PICs are an exciting piece of technology; they need a killer use case. There was a lot of progress and discussion on the topic, including an energetic Rump session hosted by Jose Pozo, CTO at Optica.
However, there is still an open question about what use cases will command volumes approaching 100,000 units, a critical milestone for mass adoption. PICs will be a key area to watch for me.
We’re also getting more clarity on the benefits of ZR+ for carriers, with transport through existing reconfigurable optical add-drop multiplexer (ROADM) infrastructures. Well done to the industry for getting to this point.
All in all, ECOC 2022 was a great success. As one of the Technical Programme Committee (TPC) Chairs for ECOC 2023 in Glasgow, we are already building on the great show in Basel. I look forward to seeing everyone again in Glasgow next year.
Sylvie Menezo, CEO of Scintil Photonics
What developments and trends did I note at ECOC? There is a lot of development work on emergent hybrid modulators.
Scott Schube, Senior Director of Strategic Marketing and Business Development, Silicon Photonics Products Division at Intel.
There were not a huge amount of disruptive announcements at the show. I expect the OFC 2023 event will have more, particularly around 200 gigabit-per-lane direct-detect optics.
Several optics vendors showed progress on 800 gigabit/ 2×400 gigabit optical transceiver development. There are now more vendors, more flavours and more components.
Generalising a bit, 800 gigabit seems to be one case where the optics are ready ahead of time, certainly ahead of the market volume ramp.
There may be common-sense lessons from this, such as the benefits of technology reuse, that the industry can take into discussions about the next generation of optics.
Alan Liu, CEO of Quintessent
Several talks focused on the need for high wavelength count dense wavelength division multiplexing (DWDM) optics in emerging use cases such as artificial intelligence/ machine learning interconnects.
Intel and Nvidia shared their vision for DWDM silicon photonics-based optical I/O. Chris Cole discussed the CW-WDM MSA on the show floor, looking past the current Ethernet roadmap at finer DWDM wavelength grids for such applications. Ayar Labs/Sivers had a DFB array DWDM light source demo, and we saw impressive research from Professor Keren Bergman’s group.
An ecosystem is coalescing around this area, with a healthy portfolio and pipeline of solutions being innovated on by multiple parties, including Quintessent.
The heterogeneous integration workshop was standing room only despite being the first session on a Sunday morning.
In particular, heterogeneously integrated silicon photonics at the foundry level was an emergent theme as we heard updates from Tower, Intel, imec, and X-Celeprint, among other great talks. DARPA has played – and plays – a key role in seeding the technology development and was also present to review such efforts.
Fibre-attach solutions are an area to watch, in particular for dense applications requiring a high number of fibres per chip. There is some interesting innovation in this area, such as from Teramount and Suss Micro-Optics among others.
Shortly after ECOC, Intel also showcased a pluggable fibre attach solution for co-packaged optics.
Reducing the fibre packaging challenge is another reason to employ higher wavelength count architectures and DWDM to reduce the number of fibres needed for a given aggregate bandwidth.
ECOC 2022 Reflections - Part 1
Gazettabyte is asking industry and academic figures for their thoughts after attending ECOC 2022, held in Basel, Switzerland. In particular, what developments and trends they noted, what they learned, and what, if anything, surprised them.
In Part 1, Infinera’s David Welch, Cignal AI’s Scott Wilkinson, University of Cambridge’s Professor Seb Savory, and Huawei’s Maxim Kuschnerov share their thoughts.
David Welch, Chief Innovation Officer and Founder of Infinera
First, we had great meetings. It was exciting to be back to a live, face-to-face industry event. It was also great to see strong attendance from so many European carriers.
Point-to-multipoint developments were a hot topic in our engagements with service providers and component suppliers. It was also evident in the attendance and excitement at the Open XR Forum Symposium, as well as the vendor demos.
We’re seeing that QSFP-DD ZR+ is a book-ended solution for carriers; interoperability requirements are centred on the CFEC (concatenated or cascaded FEC) market; oFEC (Open FEC) is not being deployed.
Management of pluggables in the optical layer is critical to their network deployment, while network efficiency and power reduction are top of mind.
The definition of ZR and ZR+ needs to be subdivided further into ZR – CFEC, ZR+ – oFEC, and ZR+-HP (high performance), which is a book-ended solution.
Scott T. Wilkinson, Lead Analyst, Optical Components, Cignal AI.
The show was invaluable, given this was our first ECOC since Cignal AI launched its optical components coverage.
Coherent optics announcements from the show did not follow the usual bigger-faster-stronger pattern, as the success of 400ZR has convinced operators and vendors to look at coherent at the edge and inside the data centre.
100ZR for access, the upcoming 800ZR specifications from the OIF, and coherent LR (coherent designed for 2km-10km) will revolutionise how coherent optics are used in networks.
Alongside the coherent announcements were developments from the direct-detect vendors demonstrating or previewing key technologies for 800 Gigabit Ethernet (GbE) and 1.6 Terabit Ethernet (TbE) modules.
800GbE is nearly ready for prime time, awaiting completion of systems based on the newest 112 gigabit-per-second (Gbps) serialiser-deserialiser (serdes) switches. The technology for 224Gbps serdes is just starting to emerge and looks promising for products in late 2024 or 2025.
While there were no unexpected developments at the show, it was great to compare developments across the industry and understand the impact of supply chain issues, operator deployment plans, and any hints of oversupply.
We came away optimistic about continued growth in optical components shipments and revenue into 2023.
Seb Savory, Professor of Optical Fibre Communication, University of Cambridge
My overwhelming sense from ECOC was it was great to be meeting in person again. I must confess I was looking at logistics as much as content with a view to ECOC 2023 in Glasgow where I will be a technical programme committee chair.
Maxim Kuschnerov, Director of the Optical and Quantum Communications Laboratory at Huawei
In the last 12 months, the industry has got more technical clarification regarding next-generation 800ZR and 800LR coherent pluggables.
While 800ZR’s use case seems to be definitely in the ZR+ regime, including 400 gigabit covering metro and long-haul, the case for 800LR is less clear.
Some proponents argue that this is a building block toward 1.6TbE and the path of coherence inside the data centre.
Although intensity-modulation direct detection (IMDD) faces technical barriers to scaling wavelength division multiplexing to 8×200 gigabit, the technological options for beyond 800-gigabit coherent aren’t converging either.
In the mix are 4×400 gigabit, 2×800 gigabit and 1×1.6 terabit, making the question of how low-cost and low-power coherent can scale into data centre applications one of the most interesting technical challenges for the coming years.
Arista continues making a case for a pluggable roadmap through the decade based on 200-gigabit serdes.
With module power envelopes of around 40W at the faceplate, it shows the challenge that the industry is facing and the case co-packaged optics is trying to make.
However, putting all the power into, or next to, the switching chip doesn’t make the cooling problem any less problematic. Here, I wonder if Avicena’s microLED technology could benefit next-generation chip-to-chip or die-to-die interconnects by dropping the high-speed serdes altogether and thus avoiding the huge overhead current input-output (I/O) is placing on data centre networking.
It was great to see the demo of the 200-gigabit PAM-4 externally modulated laser (EML) at Coherent’s booth delivering high-quality eye diagrams. The technology is getting more mature, and next year will receive much exposure in the broader ecosystem.
As for every conference, we have seen the usual presentations on Infinera’s XR Optics. Point-to-multipoint coherent is a great technology looking for a use case, but it is several years too early.
At ECOC’s Market Focus, Dave Welch put up a slide on the XR ecosystem, showing several end users, several system OEMs and a single component vendor – Infinera. I think one can leave it at this for now without further comment.