Transceivers

International growth opportunities for the photonics ecosystem, provided challenges around talent, scale-up and technology are solved 

Faster, lighter, more durable, and, at the end of the day, also much cheaper: the benefits of photonic circuits are considerable, for a wide range of applications. And the Netherlands plays an important role, globally, in the development and application of this key technology. In recent years, under the leadership of PhotonDelta, a solid foundation has been laid under the Dutch integrated photonics ecosystem. In the final episode of this series, we survey the playing field with Kathleen Philips (imec) and Boudewijn Docter (EFFECT Photonics). Read the whole series here.

Things are going well for the Dutch ecosystem around integrated photonics. Thanks to the perspectives shared by renowned representatives of this rapidly emerging industry in this series of articles, we learned that an international breakthrough is just around the corner. Obviously, this won’t be possible without a lot of investments. But in addition to that, general manager Kathleen Philips of imec at Holst Centre, three factors are all-important: choosing the right technology, growing into an ‘economy of scale’, and talent.

Imec’s headquarters are in Leuven; in the Netherlands, the renowned research institute is based in Eindhoven (as part of Holst Centre on the High Tech Campus) and Wageningen (with the OnePlanet Research Center). Although the Netherlands is primarily committed to Indium Phosphide (InP) and Silicon Nitride (SiN) production platforms, Kathleen Philips would like to make a case for internationalizing by joining CMOS-based work platforms such as Silicon Photonics (SiPh). “It offers the best opportunities for international support and that is essential for our growth ambitions.”

What is (integrated) photonics? Photonics is similar to electronics. However, instead of electrons, it uses photons (light) to transmit information. Photonic technology detects, generates, transports, and processes light. Current applications include solar cells, sensors, and fiber-optic networks. Photonic chips, officially called Photonic Integrated Circuits (PICs), integrate various photonic and often electronic functions into a microchip to make smaller, faster, and more energy-efficient devices. Because they are manufactured like traditional chips (with wafer-scale technology), mass production is also within reach – with price drop as a result. More here.

At imec, Kathleen Philips has an excellent overview of the status of photonics developments in the Netherlands and Belgium. She is thus able to combine the Dutch emphasis on Indium Phosphide and Silicon Nitride with the ‘Leuven’ expertise on Silicon Photonics. “We must be careful not to operate in ‘splendid isolation’. It is precisely in the hybrid combination of platforms that we find the desired connection to the world stage. Moreover, silicon photonics is largely compatible with classical and mainstream CMOS chip production lines, the value of which should never be underestimated. That said; if you need good lasers or low-loss waveguides, then InP and SiN platforms are an essential complement.”

Top-Notch

The next step is in creating an economy of scale, says Philips. “High volume is needed to lower the price of the end product. This automatically means you have to look across borders. Even a European scale is insufficient in that respect; we also have to focus on America and Asia. In photonics, you see the same development as in the semiconductor industry: the promise lies in the high volumes. We know that by scaling up the price goes down.”

The Netherlands has everything it needs to make that leap, Philips emphasizes. “You have to be top-notch to make an impact worldwide. And fortunately, we are. Our R&D is renowned, also historically. We are excellently positioned to connect with the big American flagships, for example. With Eindhoven, Twente and Delft we have academic gems. Their research, their publications, their professors, but also the rich ecosystem of start-ups around them and of course Photondelta: it’s all exactly how we would want to see it. Combine that with the presence of a solid high tech industry with major corporations such as ASML and NXP, and institutes like TNO and imec, and you know that a lot of good things are awaiting us.”

But, Philips warns, “to be successful we must be prepared to look beyond the important Dutch photonics industry and also strategically align ourselves internationally. In particular, the Dutch-Flemish axis offers wonderful opportunities and imec can play a connecting role. From Holst Centre in Eindhoven, we work closely with all the Dutch representatives of the ecosystem. Our colleagues in Leuven have strong international roots, with complementary technology and knowledge.” What helps, she adds, is that both at the Dutch and European level the realization has sunk in that governments can also help financially in this regard. Imec already makes use of Interreg subsidies, but the EU Chips Act is also full of promise in this regard. “And at a national level, there is a chance that the photonics sector can make use of the funding that is going to be distributed through the National Growth Fund. In short: there is much more awareness than before that public investment is important here.”

Talent

In a growth market, finding sufficient talent is always a challenge. In the photonics industry, it is no different. There is no shortage of good universities, says Philips. She mentions the three Dutch Universities of Technology, as well as those of Ghent, Leuven, and Brussels as important centers of expertise. “But you also need crown jewels: companies that capture the imagination so much that they manage to attract the best people, wherever they come from.” As an example, she points to EFFECT Photonics, founded in Eindhoven but grown – in a relatively short time – into a scale-up with some 250 people and offices around the world. “With that, EFFECT also shows how important scaling up is; not just for the company itself, but for our entire ecosystem.”

Indeed, the increasing awareness of EFFECT’s achievements has resulted in more talents knocking on their door. “But in addition to that, we also reach out to the talents ourselves,” adds founder Boudewijn Docter. “In fact, that’s one of the main reasons for our recent acquisition in the United States. We see that young people from all over the world have no trouble finding their way to Eindhoven. Recent graduates and PhDs, for example. They are very important, but we also need more experienced people and for them, it is often more difficult to leave hearth and home for a new workplace on the other side of the world.” And yet it is precisely those people who are desperately needed, Docter says. “The most important engineering skills can only be learned in practice. For the phase in which we are now, trial and error is no longer enough – we also need solid experience.”

This desire to hire more experienced people also leads to more remote work. “But even then, we would like people to come to Eindhoven from time to time, especially if they are working on multidisciplinary projects.” The best is a mix of young and experienced, in-house and remote. “With such a mix, young people find the best circumstances to grow, because they can take an example from their colleagues with a bit more experience.”

Volume

Docter is convinced that the choice to locate EFFECT’s business in places where the talent can be found ultimately also offers advantages for the Netherlands. “By growing all over the world, we become more visible as part of the national and European ecosystem. That in itself then attracts new talent, allowing the entire industry to grow.” This, in turn, is beneficial for this economy of scale also desired by Kathleen Philips. “In the semiconductor industry you always need volume”, Docter also says. “Because only then do you really start to notice the advantages. You have to know which markets you want to work for. For example, do you opt for a flexible design of your device, or a very specific one? Either way, you need to improve and stabilize your manufacturing process, which consists of hundreds of steps. Each step must deliver a 99.9999% yield, but it takes time to get there. Not only for us, by the way, but for all stakeholders in our industry, even the biggest ones. We have not yet built up sufficient experience for ‘First Time Right’, with the reliability that goes with such an ambition, but partly due to the focus on volume, we are already very well on our way to maturity.”

The imec model

Kathleen Philips is pleased that imec can play an important role in this global development. “The imec model, in which we set up R&D programs with various partners in a precompetitive setting, and our emphasis on the integration of different production platforms are essential. We are that neutral zone within which you can technically try out new ideas, and test a prototype in the value chain with limited costs. Sometimes this leads to the creation of new start-ups, or to collaboration with existing parties. But always it creates new or stronger ecosystems that the entire industry can benefit from.”

Tags: green, green transceivers, Integrated Photonics, optical transceivers, photonic integration, Photonics, pluggables, Transceivers, tuneability

In the coming decade, the network providers and countries with the most extensive installed base of optical fiber with the highest capacity will dominate the access network domain. This scale-up process will allow optical networks to handle the ongoing exponential increase in the global demand for data. To cope with this need, providers have long dreamed of implementing the concept of IP over DWDM (IPoDWDM), in which DWDM optics are integrated into the router. However, widely deploying IPoDWDM with coherent optics forced operators to face two key obstacles: the router faceplate trade-off and the performance trade-off. Significant advances in electronic and photonic integration overcame the faceplate trade-off, miniaturizing coherent line card transponders into pluggable modules the size of a large USB stick. However, even if DWDM optics could finally match the required router faceplate density, they sacrificed launch power and reach. This trade-off between size and performance has forced carriers into a dilemma when deploying new network upgrades. Pluggable transceivers enable more affordable upgrades, but their limited reach means they cannot cover the entire transport network. Meanwhile, coherent line cards provide enough performance to cover all the network links, but they are big and expensive, so carriers must try to push their vendors for lower prices. Fortunately, further advances in photonic integration allow operators to overcome this performance trade-off. Transceivers with fully-integrated optical systems on chip (SoC) can provide the performance, footprint, and versatility to cover the entire optical network..

Moving IP over DWDM from Datacom to Telecom

The viability of IP over DWDM (IPoDWDM) solutions was a major factor in the rise of coherent pluggables for datacenter interconnects. By integrating DWDM pluggable optics into the router, IPoDWDM eliminates the optical transponder shelf as well as the optics between the routers and DWDM systems, reducing the network capital expenditure (CAPEX).

However, widely deploying IPoDWDM with coherent optics forced providers to face the router faceplate trade-off. Since DWDM modules have traditionally been much larger than the client optics, plugging DWDM modules into the router required sacrificing roughly half of the very expensive router faceplate capacity. Telecom operators could not accept such a trade-off. Advances in electronic and photonic integration overcame the faceplate trade-off. They allowed the Optical Internetworking Forum (OIF) to create the  400ZR standard for 400G DWDM pluggable modules with QSFP-DD and OSFP form factors. With small enough modules to pack a router faceplate densely, the datacom sector could profit from an ideal solution for high-capacity data center interconnects of up to 80km. Telecom operators want to implement a similar IPoDWDM solution, but 400ZR standards did not have the reach for the longer links of telecom transport networks, which span several hundreds of kilometers. Extended reach 400ZR+ standards have been developed to handle these longer links, but in multi-span transport networks with ROADMs, their reach is limited to roughly 250km. Since only half of the links in a carrier’s network are less than 250km long, 400ZR+ pluggables cannot cover most of a carrier’s transport network without needing some external, additional amplifier. Since mixing pluggable and line card technologies would lead to complications in network routing and management, several carriers have chosen to prioritize network coverage and stick to the old line card transponder.

A System-on-Chip Enables Greater Reach

The reach trade-off happens because the QSFP-DD form factors could not fit optical amplifier components, limiting the transmit power and reach of the transceiver. Furthermore, lasers in most QSFP modules are still discrete: manufactured on a separate chip and then packaged with the photonic integrated circuit (PIC). A discrete laser carries a power penalty because of the losses incurred when connecting it to the PIC. On the other hand, big transponders could easily fit amplifiers to deliver best-in-class performance, reaching 1500km link lengths that could cover all the different link lengths in the carrier network. Fortunately for the industry, further improvements in integration are overcoming the reach trade-off. For example, by integrating all photonic functions on a single chip, including lasers and optical amplifiers, EFFECT Photonics’ optical System-On-Chip (SoC) technology can achieve transmit power levels similar to those of transponders while keeping the smaller QSFP-DD form factor, power consumption, and cost.

An optical SoC approach increases the transmitter’s launch power by including semiconductor optical amplifiers (SOAs) on the chip and minimizing the optical losses by placing the laser and SOAs elements on the same chip as the rest of the components. Line card transponders are still the best bet for the most extended links (ultra-long-haul, submarine) and for implementing non-standard constellation schemes. However, for many other use cases, pluggable modules can finally match the performance of line card transponders.

One plug to rule all network links

On-chip amplification also adds versatility to QSFP modules because of the SOAs tunability. By tuning the SOAs upwards, the QSFP transceiver can operate in a high-performance mode, with high-transmit power and high receiver sensitivity. With the right forward error correction (FEC), this high-performance SoC module can handle borderline long-haul links (about 1000km). On the other hand, tuning the SOAs down would enable an energy-efficient mode that could serve more lenient, shorter-reach use cases (links < 250km). To show how this versatility becomes useful, let’s look at a real-life example. British Telecom studied the links in their UK network that they would upgrade to 400G. They wanted to interconnect 106 sites (including ten hub sites) with links that contained ROADMs and typical G.652 fiber. BT found that open ZR+ transceivers could only cover 50% of the brownfield links containing ROADMs (links lengths less than 250km), while X-ponder line cards can cover all brownfield links.

A QSFP with an optical SoC that includes lasers and SOAs could deliver enough power and reach for 1000 km links, covering 97% of the links in BT’s network. Meanwhile, worldwide studies have looked at brownfield links deployed in America, Europe, and Asia and estimate that 80% of these links are less than 1000 km. The proposed module could also cover these links.

 

Takeaways

Telecom carriers need to scale up their transport networks affordably, and solutions such as IPoDWDM can help achieve this goal. Coherent pluggable modules with a fully integrated optical System-on-Chip (SoC) can help overcome the performance trade-offs that prevented the broader deployment of IPoDWDM solutions in carrier transport networks. SoC devices maximize the bandwidth density of optical transceivers, enabling transponder line card performance in a pluggable form factor. Thanks to their on-chip tunable amplifiers, the modules with an optical SoC can operate in high and low power modes that cover almost every link in an operator’s network. This way, a single versatile pluggable can take care of a carrier’s future network upgrades. Tags: green, green transceivers, Integrated Photonics, optical transceivers, photonic integration, Photonics, pluggables, Transceivers, tuneability

Thanks to the incredible progress in energy-saving technologies (hyperscale datacenters, photonic and electronic integration), the exponential growth in data traffic for the next ten years will not lead to an exponential growth in ICT energy consumption. A 2020 study by Huawei Technologies estimates that from 2020 to 2030, global data traffic will grow 14 times while ICT energy consumption will just increase 1.5 times. Telecom operators, customers, employees, and investors are all paying more attention to sustainability.

 A study commissioned by Vertiv surveyed 501 telecom enterprises worldwide, and 24% of them thought that energy efficiency should be their first priority when deploying 5G networks, while 16% saw it as their second priority. People are more likely to work for and buy products from companies with clear and ambitious sustainability goals. Investors and shareholders demand risk premiums from assets that underperform on climate goals, which often happens with fossil fuel companies. Such risk premiums could carry over to the telecom and datacom sectors. Sustainability is no longer just a matter of corporate social responsibility; it has real financial consequences.

However, there’s even more to the sustainability story. The telecom and datacom industries should become more sustainable not just because investors and customers like it, but also because it can lead to affordable ways to scale up capacity. After all, sustainable systems are efficient systems that  are often smaller, more affordable, and require less energy spending. In this article, we will dive into one of an example of this trend by explaining how compact, fully-integrated optical transceivers can play an essential role in transitioning towards a greener and more affordable telecom infrastructure.

Telecom Equipment Dissipates Heat…and Money

Data centers and 5G networks might be hot commodities, but the infrastructure that enables them runs even hotter. Electronic equipment generates plenty of heat, and the more heat energy an electronic device dissipates, the more money and energy must be spent to cool it down. The Uptime Institute estimates that the average power usage effectiveness (PUE) ratio for data centers in 2020 is 1.58.

This number means that, on average, every 1 kWh required to power ICT equipment needs an additional 0.58 kWh for auxiliary equipment such as lighting and especially cooling. Datacenter PUE will decrease in the coming decade thanks to the emergence of hyperscale data centers, but the exponential increase of data traffic and 5G services also means that more data centers must be built too, especially on the network edges. For all the bad reputation that datacenters receive for their energy consumption, wireless transmission generates even more heat than wired links. While 5G standards are more energy-efficient per bit than 4G, the total power consumption will be much higher than 4G. Huawei expects that the maximum power consumption of one of their 5G base stations will be 68% higher than their 4G stations.

To make things worse, the use of higher frequency spectrum bands and new Internet-of-Things use cases requires the deployment of more base stations too. Prof. Earl McCune from TU Delft estimates that nine out of ten watts of electrical power in 5G systems turn into heat. This issue is why the Huawei also expects that the energy consumption of wireless access networks will increase even more quickly than that of data centers in the next ten years—more than quadrupling between 2020 and 2030.

These issues do not just affect the environment but also the bottom lines of communications companies. McKinsey reports that by the end of 2018, energy costs already represented 5% of operating expenditures for telecom operators. These costs will increase even further with the exponential growth of traffic and the deployment of 5G networks.

Compactness Makes Integrated Photonics Cool

Decreasing energy consumption and costs requires more efficient equipment, and a key to achieving this goal is to increase the use of photonics and miniaturization. Photonics has several properties that improve energy efficiency. Light transmitted over an optical fiber can carry more data faster and over longer distances than electric signals over wires, while dissipating less heat. Due to their longer reach, optical signals also save power compared to electrical signals by reducing the number of times the signal needs regeneration. 

Photonics can also play a key role in rethinking the architecture of data centers. Photonics enables a more decentralized system of datacentres with branches in different geographical areas connected through high-speed optical fiber links to cope with the strain of data center clusters on power grids.

For example, data centers can relocate to areas where spare power capacity is available, preferably from nearby renewable energy sources. Efficiency can increase further by sending data to branches with spare capacity. The Dutch government has already proposed this kind of decentralization as part of their spatial strategy for data centers.

As we have explained in previous articles, miniaturization of telecom technology can also improve energy efficiency and affordability. For example, over the last decade coherent optical systems have been miniaturized from big, expensive line cards to small pluggables the size of a large USB stick. These compact transceivers with highly integrated optics and electronics have shorter interconnections, fewer losses, and more elements per chip area. These features all lead to a reduced power consumption over the last decade, as shown in the figure below.

Transceivers can decrease their energy consumption further by using an optical System-On-Chip (SoC). The SoC integrates all photonic functions on a single chip, including lasers and amplifiers. This full integration leads to simpler and more efficient interconnections between optical elements, which leads to lower losses and heat dissipation. Optical SoCs also allow coherent transceivers to have a similar reach to line card transponders for use cases up to 400G, so the industry does not have to choose between size and performance anymore.

Wafer Scale Processes Make Integrated Photonics Affordable

Previously, deploying coherent technology required investing in large and expensive transponder equipment on both sides of the optical link. The rise of integrated photonics has not only reduced the footprint and energy consumption of coherent transceivers but also their cost. The economics of scale principles that rule the semiconductor industry reduce the cost of optical SoCs and the transceivers that use them. SoCs minimize the footprint of the optics, allowing transceiver developers to fit more optics within a single wafer, which decreases the price of each individual optical system. As the graphic below shows, the more chips and wafers are produced, the lower the cost per chip becomes.

Integrating all optical components—including the laser—on a single chip shifts the complexity from the expensive assembly and packaging process to the more affordable and scalable semiconductor wafer process. For example, it’s much easier to combine optical components on a wafer at a high-volume than it is to align components from different chips together in the assembly process. This shift to wafer processes also helps drives down the cost of the device.

Takeaways

Pluggable transceivers with compact, highly-integrated optics are more energy efficient and therefore save money in network operational expenditures such as cooling. They can even lead to datacenter architectures that make the most out of the existing electricity and processing resources, allowing cloud providers to make the most of their big infrastructure investments.

By integrating all the optical components in a single SoC, more of them can fit on a single wafer and scale up to higher production volumes. Thanks to the economics of scale, higher volume production leads to lower sales prices, which reduces operators’ capital expenditures too. Due to all the reasons described above, it should now be clear why these greener pluggable transceivers will become a key factor in the successful and profitable deployment of coherent technology in future access networks.

Tags: green, green transceivers, Integrated Photonics, optical transceivers, photonic integration, Photonics, pluggables, Transceivers, tuneability