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Insights

April 28, 2022

Co-Designing Optics and Electronics for Versatile and Green Transceivers

Network and data center operators need fast and affordable pluggable transceivers that perform well enough…

Network and data center operators need fast and affordable pluggable transceivers that perform well enough to cover a wide range of link lengths. However, power consumption and thermal management are the big obstacles in the roadmap to scale high-speed transceivers into Terabit speeds.

Over the last two decades, power ratings for pluggable modules have increased as we moved from direct detection to more power-hungry coherent transmission: from 2W for SFP modules to 3.5 W for QSFP modules and now to 14W for QSSFP-DD and 21.1W for OSFP form factors. Rockley Photonics researchers estimate that a future electronic switch filled with 800G modules would draw around 1 kW of power just for the optical modules.

Around 50% of a coherent transceiver’s power consumption goes into the digital signal processing (DSP) chip that also performs the functions of clock data recovery (CDR), optical-electrical gear-boxing, and lane switching. Scaling to higher bandwidths leads to even more losses and energy consumption from the DSP chip and its radiofrequency (RF) interconnects with the optical engine.

Figure 1: Normalized power breakdown of the internal blocks of a 400ZR pluggable module. Although this breakdown may vary a bit among different vendors, the authors find it to be generally true for various DSP-based modules, both IM-DD and coherent. Source: R. Nagarajan et al., IEEE JLT (2021)

Thus, a great incentive exists to optimize the interface between the module’s DSP chip and the optical engine to make the transceiver more energy efficient. This need for optimization and efficiency makes co-designing the optical and electronic systems of the transceiver more important than ever.

Co-Designing the Optimal DSP

Coherent DSPs are already application-specific integrated circuits (ASICs), but they could fit their respective optical engines and use cases even more tightly. Transceiver developers often source their DSP, laser, and optical engine from different suppliers, so all these chips are designed separately from each other. This setup reduces the time to market and simplifies the research and design processes but comes with trade-offs in performance and power consumption.

In such cases, the DSP is like a Swiss army knife: a jack of all trades designed for different kinds of PIC but a master of none. For example, many 400ZR+ transceivers used for telecom metro and long-haul applications are using the same DSPs as 400ZR transceivers used for much shorter data center interconnects. Given the ever-increasing demand for capacity and the need for sustainability both as financial and social responsibility, transceiver developers are increasingly in need of a steak knife rather than a Swiss army knife.

Co-designing the DSP chip alongside the photonic integrated circuit (PIC) can lead to a much better fit between these components. A co-design approach helps identify in greater detail the trade-offs between various parameters in the DSP and PIC and thus improve system-level performance optimization. A DSP optimized for a specific optical engine and application could save up to a couple of Watts of power compared to the usual transceiver and DSP designs.

Figure 2: Simplified diagram of the building blocks of a coherent QSFP-DD transceiver. Original diagram source: Infinera

Co-designing DSP Interfaces for Power Efficiency

Since the optical engine and DSP operate with signals of differing intensities, they need some analog electronic components to “talk” to each other. On the transmit side, the electronic driver block takes signals from the DSP, converts them to a higher voltage, and drives the optical engine. On the receive side, a trans-impedance amplifier (TIA) block will boost the weak signal captured by the optical detector so that the DSP can more easily process it. This signal power conversion overhead constitutes roughly 10-15% of transceiver power consumption, as shown in Figure 1.

Co-designing the DSP and PIC could enable ways to decrease this power conversion overhead. For example, the modulator of the optical engine could be designed to run at a lower voltage that is more compatible with the signal output of the DSP. This way, the DSP could drive the optical engine directly without the need for the analog electronic driver. Such a setup could save roughly two watts of power consumption!

Figure-dac grey blocks — Figure 3: Simplified diagram of the building blocks of a coherent QSFP-DD transceiver in which the DSP drives the optical engine directly from its digital-to-analog converter (DAC). This setup can achieve a power consumption improvement of 10-15%.

Co-design is also vital to optimize the transceiver layout floorplan. This plan must consider the power dissipation of all transceiver building blocks to avoid hot spots and thermal interference from the DSP to the highly thermally sensitive PIC. The positioning of all bond pads and interfaces is also very important for signal and power integrity, requiring a co-design with the package and substrate.

During this floorplan development, the RF interconnections between the DSP and PIC can be made as short as possible. These optimized RF interconnects reduce the optical and thermal losses in the transceiver package and will reduce the power consumption of the analog electronic driver and amplifier.

Co-Designing Fit-For-Purpose DSPs and PICs

As shown in Figure 4, a DSP chip contains a sequence of processing blocks that compensate for different transmission issues in the fiber and then recover, decode, and error-correct the data streams. Different applications might require slightly different layouts of the DSP or might not need some processing blocks.

Figure 4: Simplified diagram of the processing blocks of a DSP chip.

For example, full DSP compensation might be required for long links that span several hundreds of kilometers, but a shorter link might not require all the DSP functions. In these cases, a transceiver could turn off or reduce certain DSP functions—such as chromatic dispersion compensation—to save power. These power-saving features could be particularly useful for the cases of shorter data center interconnect links (DCI). On the optical engine side, the laser might not require a high power to transmit over this shorter DCI link so the amplifier functions could shut down. Co-designing the DSP and PIC allows a transceiver developer to mix and match these different energy-saving features to achieve the lowest possible power for a specific application.

Takeaways

Power consumption has become the big barrier that prevents pluggable transceivers from scaling up to 800G and Terabit speeds. Overcoming this barrier requires a tighter fit between the optics and electronics of the transceiver, especially when it comes to the interface between the optical engine and the electronic DSP. By co-designing the optical engine and the electronic DSP, transceiver developers could avoid the need for an external electrical driver and reduce transceiver power consumption by 10-15%. A co-design approach can also make it easier to design fit-for-purpose transceivers that implement power-saving features tailored to specific application cases.

The benefits of this co-design approach led EFFECT Photonics to incorporate talent and intellectual property from Viasat’s Coherent DSP team. With this merger, EFFECT Photonics aims to co-design our Optical System-On-Chip with the DSP to develop fit-for-purpose transceivers that are more energy-efficient than ever before.

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Tags: acquisition, coherent, coherent communication systems, coherent optical module vendor, DSP, FEC, forward error correction, green, green transceivers, high vertical integration, independent coherent optical module vendor, Integrated Photonics, optical digital signal processing, optical engine, optical transceivers, photonic integration, Photonics, pluggables, Transceivers, tunable laser, tuneability

Reconfigurable DSPs for Versatile Pluggables

Insights

April 20, 2022

Reconfigurable DSPs for Versatile Pluggables

Carriers must solve the dilemma of how to use small and affordable coherent pluggables while…

Carriers must solve the dilemma of how to use small and affordable coherent pluggables while still having enough performance and reach to cover most of their network links. At EFFECT Photonics, we believe coherent pluggables with an optical System-on-Chip (SoC) can play a vital role in solving this carrier’s dilemma and simplifying network upgrades. Meanwhile, these new coherent pluggables could also enable longer, and higher-capacity data center interconnects for more sustainable data center architectures.

Another big factor in making networks more affordable and sustainable is software-defined networks (SDNs) and automation. SDNs enable the network function virtualization (NFV), which allows operators to implement more functions to manage and orchestrate the network. Operators will reap even further benefits by using an artificial intelligence (AI) management and orchestration layer with the SDN/NFV layer, as shown in the figure below.

Figure 1: Example of a carrier network with different applications (mobile, home, office) automated via NFV control and AI management.

However, creating a fully automated network that can handle the ever-increasing amount of data and connected devices requires us to go beyond just adjusting the higher network layers. The orchestration and management software should also interface with the physical layer of the network, and that requires smart optical pluggable that adapt to varying network requirements. These requirements place additional burdens on digital signal processors (DSPs). DSPs are a vital component of coherent communication systems, as they perform the coding, decoding, and error corrections on the optical signal. Fortunately, the advances in electronic integration and standards make it so that a versatile coherent pluggable can benefit from an equally versatile and reconfigurable DSP.

Future Automated Networks Must Also Work on the Physical Layer

Telecom and datacom providers who want to become market leaders must scale up while also learning to allocate their existing network resources most efficiently and dynamically. SDNs can help achieve this efficient, dynamic network management. In a nutshell, the SDN paradigm separates the switching hardware from the software, allowing operators to virtualize network functions in a single centralized controller unit. This centralized management and orchestration (MANO) layer can implement network functions that the switches do not, allowing network operators to allocate network resources more intelligently and dynamically. This added flexibility and optimization will improve network outcomes for operators.

Figure 2: Comparing a traditional network approach (left) with an SDN/NFC approach (right).

However, the upcoming 5G networks will consist of a massive number of devices, software applications, and technologies. EFFECT Photonics believes that handling all these new devices and use cases will require self-managed, zero-touch automated networks. Realizing this full network automation requires two additional components alongside SDN and NFV:

Artificial intelligence and machine learning algorithms for complete network automation: For example, AI in network management will become a significant factor in reducing the energy consumption of future telecom networks.
Sensor and control data flow across all OSI model layers, including the physical layer: As networks get bigger and more complex, the management and orchestration (MANO) software needs more degrees of freedom and knobs to adjust. Next-generation MANO software needs to adjust and optimize both the physical and network layers to fit the network best.

Achieving the second goal requires smart optical equipment and components that can be diagnosed and managed remotely from the MANO layer. This context is where smart pluggable transceivers with reconfigurable DSPs come into play.

The Importance of Standardized Error Correction

Forward error correction (FEC) implemented by DSPs has become a vital component of coherent communication systems. FEC makes the coherent link much more tolerant to noise than a direct detect system and enables much longer reach and higher capacity. Thanks to FEC, coherent links can handle bit error rates that are literally a million times higher than a typical direct detect link. In other words, FEC algorithms allow the DSP to enhance the link performance without changing the hardware. This enhancement is analogous to imaging cameras: image processing algorithms allow the lenses inside your phone camera to produce a higher-quality image.

Figure 1 Simplified diagram of a network link with Forward Error Correction (FEC). — Figure 3: Simplified diagram of a network link with forward error correction (FEC). The FEC encoder adds a series of redundant bits (called overhead) to the transmitted data stream. The receiver can use this overhead to check for errors without asking the transmitter to resend the data.

When coherent transmission emerged, all FEC algorithms were proprietary. Equipment and component manufacturers closely guarded their FEC because it provided a critical competitive advantage. Therefore, coherent transceivers from different vendors could not operate with each other, and a single vendor had to be used for the entire network deployment. However, vendors had to adapt with data center providers pushing disaggregation deeper into communication networks. Their coherent transceivers needed to become interoperable, so FEC algorithms needed standardization. The OIF 400ZR standard for data center interconnects uses a public algorithm called concatenated FEC (CFEC). In contrast, some 400ZR+ MSA standards use open FEC (oFEC), which provides a more extended reach at the cost of a bit more bandwidth and energy consumption. For the longest possible link lengths (500+ kilometers), proprietary FECs become necessary for 400G transmission. Still, at least the public FEC standards have achieved interoperability for a large segment of the 400G transceiver market.

A Smart DSP to Rule All Network Links

A smart pluggable transceiver that can adapt to all the applications we have mentioned before—data centers, carrier networks, SDNs—requires an equally smart and versatile DSP. It must be a DSP that can be reconfigured via software to adapt to different network conditions and use cases. For example, a smart DSP could switch among different FEC algorithms to adapt to network performance and use cases. For example, let’s look at the case of upgrading a long metro link of 650km running at 100 Gbps with open FEC. The operator needs to increase that link capacity to 400 Gbps, but open FEC could struggle to provide the necessary link performance. However, if the DSP can be reconfigured to use a proprietary FEC standard, the transceiver will be able to handle this upgraded link.

	400ZR	Open ZR+	Proprietary Long Haul
Target Application	Edge data center interconnect	Metro, Regional data center interconnect	Long-Haul Carrier
Target Reach @ 400G	120km	500km	1000 km
Form Factor	QSFP-DD/OSFP	QSFP-DD/OSFP	QSFP-DD/OSFP
FEC	CFEC	oFEC	Proprietary
Standards / MSA	OIF	OpenZR+ MSA	Proprietary

Table 1: Summary of different use cases and standards for a 400G pluggable transceiver.

Reconfigurable DSPs can also be beneficial to auto-configure links to deal with specific network conditions, especially in brownfield links. For example, the DSP can be reconfigured to transmit at a higher baud rate if the link has a good quality fiber. However, the DSP could be reconfigured to scale down the baud rate to avoid bit errors if the fiber quality is poor. If the smart pluggable detects that the fiber length is relatively short, it could scale down the laser transmitter power or the DSP power consumption to save energy.

Takeaways

A versatile pluggable that can handle different use cases – data center links, long metro links, and dynamic management and orchestration layers – must have the ability to use different coding and error coding schemes and adapt to different network requirements. The DSP must be equally versatile and switch among several operating modes – 400ZR, 400ZR+, proprietary – and error correction methods – cFEC, oFEC, and proprietary. Together with a programmable optical system on chip, the DSP can not just add software corrections but also make optical hardware changes (output power, turn amplifiers on/off) to adapt to different noise scenarios. Through these adjustments, the next generation of pluggable transceivers will be able to handle all the telecom carrier and data center use cases we can throw at it.

Insights

April 19, 2022

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

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

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

Read about the latest technology trends, events, news, announcements and press releases regarding EFFECT Photonics.

Insights

April 13, 2022

Solving the Carrier’s Dilemma with Optical Systems-On-Chip

In the coming decade, the network providers and countries with the most extensive installed base…

Insights

March 15, 2022

Why Greener Transceivers are Profitable

Thanks to the incredible progress in energy-saving technologies (hyperscale datacenters, photonic and electronic integration), the…

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.

Figure 1: Survey of 501 telecom enterprises worldwide about their priorities when deploying 5G networks. Commissioned by Vertiv and conducted by consulting firm STL Partners on January 2021.

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.

Graph-estimated-electric-power — Figure 2: Comparison of estimated ICT electric power consumption in 2020 and 2030, divided by different ICT sectors. Source: Anders Andrae (Huawei), 2020.

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.

Figure 3: High-speed fiber-optic connections allow data processing and storage to be moved to locations where excess (green) energy is available. Data can be moved elsewhere if power is needed for other purposes, such as charging electric vehicles.

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.

Figure 4: Coherent module size and power consumption evolution from OIF MSA line card modules to pluggable modules like CFP and QSFP.

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.

Figure 5: Modelling of photonic integrated chip (PIC) cost as a function of aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost. Source: Model and graph provided by Prof. Meint Smit, TU Eindhoven.

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.

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

Press Releases

March 7, 2022

EFFECT Photonics and Jabil Photonics to Co-Develop Next-Generation Coherent Module

– EFFECT Photonics and Jabil Photonics, a business unit of Jabil Inc. (NYSE: JBL), announced…

Insights

February 10, 2022

Remote PHY, a new architecture for fixed access networks

Cable networks, just like any other telecom network in the world, had to adapt to…

Cable networks, just like any other telecom network in the world, had to adapt to the rising demand for data. During the 90s and 00s, these requirements led to the rise of hybrid fiber-coaxial (HFC) networks: optical fibers travel from the cable company hub and terminate into optical nodes, while coaxial cable connects the last few hundreds of meters from the optical node to nearby houses. These connections mainly were asymmetric, with customers having several times more bandwidth to download data than to upload.

In the past decade, the way we use the Internet has changed. With the rise of social media, online gaming, video calls, and independent content creation such as video blogging, users need more upstream bandwidth than ever. These new requirements have led to quick progress in the DOCSIS standards that regulate data transmission over coaxial cables. For example, the latest DOCSIS 4.0 standards allow full-duplex transmission with symmetrical upstream and downstream channels. Meanwhile, fiber-to-the-home (FTTH) systems—with fiber arriving directly to the customer premises—are also becoming widespread and allowing Gigabit connections that are faster than HFC networks.

Despite these upgrades in the transport mediums and standards, cable networks have experienced surprisingly few upgrades in their architectures. They still rely on centralized architectures in which the network operator’s headend performs almost all functionalities of both the physical layer (PHY) and medium access control layer (MAC). This means that the headend must modulate and demodulate data, convert between analog and digital, perform error corrections, provide cable modem termination system (CMTS) services, and do some resource allocation and flow control.

However, as traffic demands grow, cable providers need to deliver more and more bandwidth to their optical nodes and customer premises. The headend equipment is getting more congested, consuming more power, and running out of ports to handle more fiber connections. This solution centralized on the headend is struggling to scale up with increased demand. As it often happens in the telecom sector, operators need to figure out ways to deliver more bandwidth to more customers without spending significantly more money.

The multiple benefits of distributed access architectures

These issues are the reason why cable providers are moving into distributed access architectures (DAA) that can spread functionalities across access network nodes and reduce the port congestion and equipment required at the headend. Remote PHY has become increasingly popular among providers because it separates the PHY layer from the traditional cable headend and pushes its functions (such as modulation or digital-analog conversion) into the optical fiber access nodes of the network.

This shift can enhance the performance, capacity, and reliability of fixed access networks by using more digital transmission. It also reduces the complexity and power consumption of the headend, which previously translated into higher costs due to the required cooling.

Furthermore, separating PHY and MAC layers makes it easier to virtualize headends and their network functions, which significantly cuts expenses due to the use of commercial-off-the-shelf (COTS) equipment compared to more specialized equipment. Virtualization also allows deploying new services and applications more quickly to users and migrating workloads to optimize power consumption and reduce energy costs. On top of that, Remote PHY achieves all of these benefits while keeping the existing HFC infrastructure!

Figure 1: Comparison between traditional centralized architecture and Remote PHY architecture. The analog fiber link between cable headend and node is replaced by a digital link. The digital-to-analog conversion is moved from the cable headend in a centralized architecture to the Remote PHY node. In this new architecture, the new cable headend is called “CCAP Core”, as it doesn’t perform all the functions of a traditional Converged Cable Access Platform (CCAP) anymore.

Distributing digital-analog conversion

One of the most significant upgrades provided by Remote PHY networks is digital transmission deeper into the access network. In Remote PHY, data and video signals are kept in a digital format beyond the core headend, all the way into the upgraded optical node, where the signal is then converted into analog RF format. The fiber links between the headend and the access node that were previously analog will become digital fiber connections over Ethernet.

Since digital signals are more noise-tolerant than analog signals, the network benefits from this increased digital transmission length. Analog and radiofrequency signals now travel smaller distances to reach customer premises, so the signal accumulates less noise and boosts its signal-to-noise ratio. This improvement potentially allows the delivery of higher bandwidth signals to customers, including an increase in upstream bandwidth. Furthermore, the reliability of the link between the headend and the new optical node increases due to the greater robustness of digital links. These advances in reliability and performance make digital optics more affordable to buy and maintain than analog optics, reducing the costs for the network operators.

Let’s provide a very simplified example of how it all comes together. A network operator wants to increase their bandwidth and serve more customers, but their traditional centralized headend is already crowded with eight analog optical fiber links of 1Gbps each. There is no room to upgrade.

By installing Remote PHY technology in both the headend and the node, those analog links can be replaced by higher-capacity 10G digital links. The increased capacity at the headend allows for more optical node splits, while the new digital-to-analog conversion capability of the nodes allows them to care of more coaxial splits, all to serve new areas and customers.

Using DWDM in Remote PHY

The tremendous progress in electronic and photonic integration made Dense Wavelength Division Multiplex (DWDM) technology affordable and available to access networks, and this technology is quickly becoming a workhorse in this network domain. The availability of affordable DWDM transceivers made the deployment of Remote PHY even more powerful.

With Remote PHY improving the capacity of the headend, cable access networks had more bandwidth to serve more customers. However, some ways of using that bandwidth are more efficient than others. Operators can do extra node splits for customers by using their dark fibers and more grey transceivers, but that solution doesn’t scale in so cost-effectively due to the installation and maintenance of a new fiber link. Another option is time division multiplexing (TDM), which multiplexes the data of different node channels into specific time slots. This solution allows operators to carry different node channels in a single fiber but has speed, latency, and security trade-offs. A single time-multiplexed channel cannot transmit at the same speed and latency as a dedicated channel, and the data of all node channels are in the same multiplexed optical link, so the nodes and their customers can’t have fully secure channels to themselves.

DWDM solutions, on the other hand, can avoid the speed and security trade-offs by multiplexing extra channels into different wavelengths of light. Instead of several TDM channels “splitting” the 10G bandwidth among themselves, the DWDM channels can each transmit at 10G. And since each WDM channel has its own wavelength, the channels are transmitted independently from each other, allowing users to have secure channels.

Without sharing an optical link as in TDM, DWDM channels can also provide bidirectional communication (upstream and downstream) with less electronic processing than TDM channels. This feature is particularly beneficial for the modern Internet consumption patterns described earlier in the article.

Figure 2: Example of a Remote PHY architecture with a DWDM digital link. Without needing extra fibers, the link between the headend and node has a greater capacity to accommodate new customers, like those in the apartment complex.

Let’s go back to our previous example of the upgraded headend with 10G digital fiber links. Thanks to DWDM technology, a single 10G port on this headend can support additional optical nodes in the network more cost-effectively than ever. Let’s say a new apartment complex was built, and the network operator needs to deploy a new node to service this new building. In the past, this deployment would have required lighting up a dark fiber and setting up an extra fiber link or using TDM technology with lower data rates, latency, and security. With DWDM, the new node can simply be carried through a different wavelength channel in the already existing fiber link. And as we will describe in our next article, autotuneability in DWDM transceivers makes their setup and maintenance even more affordable.

Takeaways

Cable networks need to serve more customers than ever with more symmetric upstream and downstream capacity, and they need to achieve this without changing their existing fiber and coaxial infrastructure. These goals become possible with the onset of Remote PHY and more accessible DWDM transceivers. By separating the MAC and PHY layer, Remote PHY reduces the load on the cable headend and allows for more virtualization of network functions, making it easier and more affordable to upgrade and manage the network. Meanwhile, DWDM enables connections from the headend to the Remote PHY nodes that serve tens of customers with a single fiber.

Tags: architectuyre, autotuneability, DWDM, fixed access networks, Integrated Photonics, optical transceivers, photonic integration, Photonics, pluggables, remote phy, Transceivers, tuneability

How To Make a Photonic Integrated Circuit

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January 19, 2022

Leveraging the Power of External Foundries in Photonics

Working with a world-class high-volume foundry makes scaling up from low to high volume as…

Working with a world-class high-volume foundry makes scaling up from low to high volume as easy as putting a purchase order in place. Instead of having to buy equipment, develop processes, and train operators over many years, a fabless photonics developer can leverage foundries who already have these capabilities and knowledge.

Thanks to wafer scale technology, electronics has successfully driven down cost per transistor for many decades. This allowed the world to enjoy chips that every generation became smaller and provided exponentially more computing power for the same amount of money. This scale-up process is how everyone now has a computer processor in their pocket that is millions of times more powerful than the most advanced computers of the 1960s that landed men on the moon.

This progress in electronics integration is a key factor that brought down the size and cost of coherent transceivers, packing more bits than ever into smaller areas. However, photonics has struggled to keep up with electronics, and now the optics dominate the optical transceiver’s cost. If the transceiver cost curve does not continue to decrease, it will be difficult to achieve the goal of making coherent technology more accessible across the entire optical network. This will make it more difficult to provide the services needed by cloud providers and the growing 5G access networks.

As we mentioned in our previous article, photonics manufacturing must move into wafer-scale territory to provide faster, more affordable, and sustainable coherent transmission.

However, most photonic chip developers don’t have human and financial resources to own and operate their own wafer-scale photonic foundries. Fortunately, electronic chip developers have shown a more viable and cost-effective alternative: the fabless model.

A Lower Upfront Investment

Increasing the volume of photonics manufacturing is a big challenge. Some photonic chip developers choose to manufacture their chips in-house within their own fabrication facilities. This approach has some strong advantages, as it gives component manufacturers full control over their production process. By vertically integrating the whole chip design, manufacturing, and testing process within the same company, it’s often easier to try out new changes and innovations to the product.

Figure 1: Simplified value chain diagram of a vertically-integrated optical transceiver developer. The developer handles the PIC design, manufacturing, and packaging

However, this approach has its trade-offs. If a vertically-integrated chip developer wants to scale up in volume, they must make a hefty investment in more equipment and personnel to do so. They must develop new fabrication process which not only need money, but also time to develop and train personnel. Especially in the case of an optical transceiver market that is not as big as that of consumer electronics, it’s hard not to wonder whether that initial investment is cost-effective.

Electronics manufacturing had a similar problem during their 1970s boom, with smaller chip start-ups facing almost insurmountable barriers to enter the market because of the massive capital expenditure (CapEx) required. Electronics solved this problem by moving into what we call a fabless model, with companies designing and selling the chips but outsourcing the manufacturing.

For example, transceiver DSP chip developers design the chip, but then outsource the actual fabrication to a large-volume manufacturing plant (usually called a foundry). This business model works by leveraging the design, research, development, and distribution networks of the fabless company, and the specialized manufacturing skill of the chip foundry.

Figure 2: Simplified value chain diagram of a vertically-integrated optical transceiver developer. The developer handles the PIC design, manufacturing, and packaging.

This model reduces the capital expenditure burden on the DSP developers, because instead of spending all the time and energy in scaling up their own facilities, they can work with a foundry that already did that investment and has the required manufacturing volume. In other words, instead going through a more costly, time-consuming process, the troubles of scaling up are outsourced and (from the perspective of the fabless company) become as simple as putting a purchase order in place. Furthermore, the fabless model also allows companies to concentrate their R&D resources on the end market. If photonics is to move into million-scale volumes, this is likely the way forward.

Economies of Scale and Operating Expenses

Even if an optical transceiver developer could move forward with the CapEx required for its own large-scale fab and a vertically-integrated model, market demand and operational expenses become the next pain point. Transceivers are a B2B market, and their demand is significantly smaller than of B2C consumer electronics. For example, LightCounting estimates that 55 million optical transceivers will be sold in 2021, while the International Data Corporation estimates that 1.4 billion smartphones will be sold in 2021. The latter figure is 25 times larger than that of the transceiver market.

The smaller demand of transceivers means that even if a vertically-integrated transceiver developer upgrades to a larger-scale manufacturing facility, it will likely have more manufacturing capacity than what their customers need. In such a situation, the facility could run at a reduced capacity. However, fabs are not only expensive to build, but also to operate. Unless they can be kept at nearly full utilization, operating expenses (OpEx) will become a drain on the finances of the facility owners.

This issue was something the electronics industry faced in the past, during the 1980s. Integrated electronics manufacturers had excess production capacity, and this situation paved the way for the fabless model too. The large-scale manufacturers ended up selling that excess capacity to smaller, fabless chip developers. Ultimately, the entire electronics industry relied increasingly on the fabless model, to the point where pure play foundries like the Taiwan Semiconductor Manufacturing Corporation (TSMC) appeared and focused entirely on manufacturing for other fabless companies.

In this scenario, everyone ended up winning. The foundries serviced multiple companies and could run their facilities at full capacity, while the fabless companies could outsource manufacturing and reduce their expenditures.

Working with the Best in the Business

The other advantage of pure play foundries is that they not only have state-of-the art equipment but also the best personnel and technical expertise. Even if a vertically-integrated developer transceiver can make the required CapEx to scale up their facilities, developing processes and training people inevitably takes years, delaying the return on investment even further.

By working with an established and experienced foundry, fabless companies take advantage of the highly trained and experience personnel of these facilities. These operators, technicians, and engineers have worked day in, day out with their equipment for years and already developed processes that are finely tuned to their equipment. Thanks to their work, fabless transceiver developers do not have to reinvent the wheel and come up with their own processes, saving valuable time and many, many headaches.

Takeaways

To make transceivers more accessible to world and connect more people together, transceiver developers need to reach production scales in the millions. At EFFECT Photonics, we believe that the way to achieve this goal is by having photonics follow the blueprint laid out by the electronics industry. Using a fabless model, we can reduce the capital expenditure and scale up more quickly and with fewer risks.

Tags: coherent, coherent optics, external foundries, foundries, Integrated Photonics, LightCounting, optical transceivers, photonic integration, Photonics, photonicwafer, pluggables, Transceivers, wafer

Wafer Scale Photonics for a Coherent Future

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January 12, 2022

Wafer Scale Photonics for a Coherent Future

The advances in electronic and optical integration have brought down the size and cost of…

The advances in electronic and optical integration have brought down the size and cost of the coherent transceivers, packing more bits than ever into smaller areas. However, progress in the cost and bandwidth density of transceivers might slow down soon. Electronics has achieved amazing breakthroughs in the last two decades to continue increasing transistor densities and keeping Moore’s Law alive, but these achievements have come at a price. With each new generation of electronic processors, development costs increase and the price per transistor has stagnated.

Figure 1. Evolution of foundry sale price per million transistors over successive electronic process nodes. Based on data from TSMC. Source: AI Chips: What They Are and Why They Matter, Center for Security and Emerging Technology (April 2020).

Due to these developments, electronic digital signal processor (DSP) chips will continue to improve in efficiency and footprint, but their price will stagnate and with it the price of optical transceivers. Without further improvements in the cost per bit, it will be difficult to achieve the goal of making coherent technology more accessible across the entire optical network. This will make it more difficult to provide the device volume and services needed by the growing 5G networks and cloud providers.

To make coherent transceivers more accessible, photonics has to step up now more than ever. With the cost of DSPs stagnating, photonic integration must take the lead in driving down the costs and size of optical transceivers. Integrating all optical components on a single chip makes it easier to scale up in volume, reach these size and cost targets, and ultimately provide faster, more affordable, and sustainable coherent transmission.

Size Matters

Full photonic integration allows us to combine active optical elements like the laser and the amplifer with passive elements, all on the same chip and enclosed in a simple, non-hermetic package. This process enables a much smaller device than combining several indivudally packaged elements. For example, by integrating all photonic functions on a single chip, including lasers and optical amplifiers, EFFECT Photonics’ pluggable transceiver modules can achieve transmit power levels similar to those of line card transponder modules while still keeping the smaller QSFP router pluggable form factor, power consumption, and cost.

Figure 2: Comparing transmit power, noise, size, and cost of line card transponders and different transceiver pluggable modules. Fully integrated QSFP-DD modules include lasers and amplifiers inside a single chip, so they can deliver high transmit powers at small size and low cost.

Full integration technology increases the transmit power by minimizing the optical losses due to the use of more efficient optical modulators, fewer material losses compared to silicon, and the integration of the laser device on the same chip as the rest of the optical components. The semiconductor optical amplifiers (SOAs) used in fully integrated devices can also outperform the performance of micro-EDFAs for transmission distances of at least 80km.

The Economics of Scale

As innovative as full photonic integration can be, it will have little impact if it cannot be manufactured at a high enough volume to satisfy the demands of mobile and cloud providers and drive down the cost per device. Wafer scale photonics manufacturing demands a higher upfront investment, but the resulting high-volume production line drives down the cost per device. This economy-of-scale principle is the same one behind electronics manufacturing, and the same must be applied to photonics.

The more optical components we can integrate into a single chip, the more can the price of each component decrease. The more optical System-on-Chip (SoC) devices can go into a single wafer, the more can the price of each SoC decrease. Researchers at the Technical University of Eindhoven and the JePPIX consortium have done some modelling to show how this economy of scale principle would apply to photonics. If production volumes can increase from a few thousands of chips per year to a few millions, the price per optical chip can decrease from thousands of Euros to mere tens of Euros. This must be the goal for the optical transceiver industry.

Figure 3: Modelling of photonic integrated chip (PIC) cost as a function of aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost. Source: Model and graph provided by Prof. Meint Smit, TU Eindhoven.

Full Integration Streamlines Production and Testing

Integrating all optical components on a single chip can make manufacturing and testing more efficient, sustainable, and easier to scale up. The price of photonic devices is not dominated by the manufacturing of the semiconductor chips, but by the device assembly and packaging. Assembling and packaging a device by interconnecting multiple photonic chips together leads to an increase in assembly complexity and therefore additional costs.

This situation happens frequently with the laser component, which is often manufactured on a separate chip and then interconnected to the other optical components which are on another chip. Integrating all components—including the laser—on a single chip shifts the complexity from the assembly process to the much more efficient 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 different chips together in the assembly process, and that drives down the cost of the device.

Testing is another aspect that becomes more efficient and scalable when manufacturing at the wafer level. When faults are found earlier in the testing process, fewer resources and energy are spent in process defective chips. Ideally, testing should happen not only on the final, packaged transceiver but in the earlier stages of PIC fabrication, such as measuring after wafer processing or cutting the wafer into smaller dies.

Figure 4: Package vs. die level testing. Manufacturers can find faults earlier by testing at the die level, which avoids wasting packaging materials.

Full photonic integration enables earlier optical testing on the semiconductor wafer and dies. By testing the dies and wafers directly before packaging, manufacturers need only discard the bad dies rather than the whole package, which saves time, cost, and is more energy efficient and sustainable. For example, EFFECT Photonics reaps these benefits in its production processes. 100% of electrical testing on the PICs happens at the wafer level, and our unique integration technology allows for 90% of optical testing to also happen on the wafer.

Takeaways

Photonics is facing the next stage of its development. There have been many great breakthroughs that have allowed us to take photonic devices from the lab to real-world use cases. However, to have the biggest possible impact in society, we need to manufacture photonic devices at very high volumes to make them accessible to everyone. This requires us to think about production volumes in the scale of millions of units. At EFFECT Photonics, we believe that the way to achieve this goal is by following the blueprint laid out by our friends in the electronics industry. By integrating all optical components on a single chip, we can shift more complexity from the assembly to the wafer, allowing production to scale more efficiently and sustainably. In our next article, we will elaborate on another key factor of the electronics blueprint: the fabless development model.

Tags: coherent, coherent optics, Density, Integrated Photonics, LightCounting, network operators, optical transceivers, photonic integration, Photonics, pluggables, Transceivers, Wafer Scale Photonics

Press Releases

December 15, 2021

Meet the team behind the EFFECT Photonics & Aston University partnership to bring greater bandwidth to a greener future

The optical transceiver market is expected to double in size by 2025, and coherent optical…

The optical transceiver market is expected to double in size by 2025, and coherent optical technology has come a long way over the past decade to become more accessible and thus have a greater impact on this market. When Nortel (later Ciena) introduced the first commercial coherent transponder in 2008, the device was a bulky, expensive line card with discrete components distributed on multiple circuit boards.

Recently, EFFECT Photonics and Aston University announced that they would collaborate as part of the newly formed Royal Academy of Engineering Research Chair in Highly Integrated Coherent Optical Fibre Communications.

To learn more about this industry/academic partnership, we interviewed the three lead researchers in this project: Prof. Wladek Forysiak, Dr. Ian Phillips, and Dr. Stylianos Sygletos.

Tell us a little more about yourself and the team

Wladek: My background goes back almost to the start of the Aston Institute of Photonics Technology (AIPT). AIPT was formed by a couple of guys who came out of British Telecom and what was then part of the GEC Telecom Company. The institute has deep industrial roots, and hence the people who work at AIPT often like to participate in projects close to the industry with relatively short timescales. I joined the institute as a post-doc and then subsequently became an academic staff member.

Around 2000, I left alongside five others for a “virtual startup” with the Marconi company, and we formed an entity called Marconi Solstis. At that time, we developed a record-breaking terrestrial ultra long haul system, and we installed our first system in Australia, linking the cities of Perth and Adelaide. Marconi then morphed into Ericsson, and I stayed there for another six to seven years.

In 2010, I moved to Oclaro (now Lumentum), which does somewhat similar technology to what’s being developed by EFFECT Photonics on their integrated indium phosphide platform. I spent three or four years there before returning to academic life at Aston. As for the team, we have funding for three full-time Ph.D. students we’re currently working to recruit. They will be the cement, the foundation of our project.

Ian: I’m of a similar background to Wladek. My expertise is in transceivers, especially characterization and design. I completed my Ph.D. at Aston in 1997 in optical signal processing. British Telecom (BT) sponsored the project, and I worked there for a year after my Ph.D. Corning subsequently purchased the BT Photonics Lab in 2000, and I stayed there for another year. Afterward, I moved to Marconi Solstis with Wladek and stayed there until 2010, when Ericsson closed the site. I then worked in Italy for two years, transferring some system knowledge to the Ericsson research group there, and finally, I joined Aston in 2012.

Stylianos: I completed my Ph.D. at the National Technical University of Athens in 2006, focusing on the physical layer modeling of optical communication systems. I worked for a year at Athens Information Technology (i.e., a research center of Intracom, the largest telecom system provider in Greece). Between 2007 and 2009, I moved for a post-doc position in the Karlsruhe Institute of Technology, working with Juerg Leuthold to model quantum-dot semiconductor optical amplifiers.

I then moved to the Tyndall National Institute in Ireland in 2009 to join the group of Andrew Ellis. I focused on the design and experimental implementation of phase-sensitive amplifiers and optical phase-locking solutions for these amplifiers.

After 2012, I joined AIPT as a research fellow, where my research interests eventually changed to digital signal processing and machine learning. I want to apply machine learning to the physical layer of optical communication systems. I’m now the director of two Master’s programs at Aston: the Smart Telecom and Sensing Networks (SMARTNET) and the Erasmus Mundus Photonic Integration and Networks (PIXNET), in collaboration with different universities in Europe and Japan.

What attracted you to collaborate with EFFECT Photonics?

Wladek: This project came about through a conversation between James (EFFECT Photonics’ CEO) and myself where he said, “Well, I’m interested in growing research activities to enhance our systems capability, and I have confidence in the experience of you and the Aston team”. So I said to him that one way to build a long-term relationship between a company and a university is through Ph.D. studentships.

AIPT is very much about doing applied research, and James was very much about the value of user-directed research that is close to the market and based on real-world situations. So he and I shared that vision around the partnership.

Another reason was, of course, that EFFECT Photonics has technology complementary to ours. EFFECT can be a source of advanced technology for us to build the best experiments that compete with the best in the world. Our competition is in the advanced labs of Japan, the US, and other areas in Europe, and having access to great components is key to matching their capabilities.

We also found attractive the ambition and drive of a startup company and its ability to make quick decisions. When I reached out to James with ideas, I could get an immediate yes or no answer, often on the call, for authorization.

Ian: James explained to us really well what EFFECT Photonics was doing, its ambitions, and how it aligned with our work. When we visited the facility in Brixham and were shown around the labs, it was all indicative of a company that wanted to get things done quickly, and hopefully, we can help them in that process.

Stylianos: On top of what Wladek already mentioned, it’s great to work with a startup that is more open to testing new technologies. I’m passionate about machine learning, and the prospect of applying machine learning algorithms to EFFECT Photonics’ novel technology platform is very exciting. I feel like there is an opportunity to make a big impact.

In what ways do the facilities of Aston University complement what EFFECT Photonics has?

Wladek: EFFECT Photonics develops advanced components that interest people like us working on optical communication systems and networks. We’re used to thinking about integrating these advanced components into our systems and getting the maximum capacity from point A to B.

We have a history of 30 years with optical fiber transmission, so we have all the necessary facilities for system modeling and testing. Stelios also brings to the party his expertise in DSP software, which is also critical to what EFFECT Photonics may do in the future.

Ian: We also see our job as training the Ph.D. students to pass on our knowledge of system design and how that reflects in EFFECT Photonics’ transceiver design. We want to train the students and get them to creatively and effectively use the components.

Stylianos: It depends on how the project goes, but we can even develop device models of EFFECT Photonics units and identify the device parameters that can meet network and system-level targets. We can even combine it with machine learning for extra optimization of those parameters.

What are some of the main challenges you hope to address?

Wladek: Looking for a greener future is a big challenge in optical comms. We’ve all witnessed it in the last couple of years with the pandemic. We need greater network capacity but also cheaper and greener. We cannot let that demand for capacity just be the same old technology since power consumption would go up and up and up.

The challenges are similar to what they’ve always been, in a way, but even more acute. And we need to do it all without really spending more money. Nobody wants to pay more for their comms at the end of the day.

We should also go in other directions to increase the capacity. For example, EFFECT Photonics’ current components are made for the optical C-band, but people in long-haul and other areas are looking at creating multiband components that can also operate in the L-band. We’ve also got projects currently looking at the S-band and shorter wavelengths. Researchers are also looking at different fibre structures to carry more and more signals.

At the same time, there’s an industry drive never to pay for more. Ultimately, that mindset has driven even more technical innovation. Capacity has gone up, but the price has gone down. It’s a relentless game, and everyone keeps saying there’s going to be a point at which we don’t need any more capacity, but if it’s there, we always find ways of using it.

Ian: One key challenge many companies are working on is increasing the baud rate, which is quite a technical problem. If you increase the baud rate, you increase the channel capacity too. It was stuck at around 28 GBaud for a long time, and now it’s going up 64 and even 100 GBaud.

Stylianos: I want to mention how important is network optimization to improve performance and reduce power consumption, which would lead to greener networks.

Network operators need to maintain large performance margins to secure a robust operation in different network conditions. In practice, however, these margins mean more power consumption. Ideally, you would like to reduce those margins by a more efficient design of your system and performance that can adapt to the different conditions. We can achieve these goals through machine learning.

This requires solutions for multi-objective optimization. For example, we are not just interested in designing the transmitter subsystem, but we want to see how transmitter performance is connected to network-level performance, as measured by throughput and power consumption. This is a complex problem that involves different layers of the system.

Takeaways

Moving towards a higher-capacity and greener future requires strong collaboration between academic and industrial partners with shared goals. EFFECT Photonics and Aston University share a vision around this greener future and the value of applied research.

This joint project will unite EFFECT Photonics’ component development expertise with Aston’s expertise in optical fiber transmission modeling, testing, and network optimization through machine learning. This union can enable faster, more affordable, and sustainable coherent products that give greater bandwidth to a greener future.

As Wladek mentioned in the interview, this joint project is looking for three PhD students to drive it forward, with the positions available to start in March, July, or October 2022. If you are interested in applying or know someone who might be interested, please visit the following link: https://jobs.aston.ac.uk/Vacancy.aspx?ref=R210549 .

Tags: Aston University, bandwidth, coherent, coherent optics, CoherentPIC, digital signal processing, DWDM, Green Energy, optical network, photonic integration, Photonics, programmable optical system-on-chip, Royal Academy of Engineers, sustainability telecommunication energy efficency, Sustainable

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Co-Designing the Optimal DSP

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Future Automated Networks Must Also Work on the Physical Layer

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Telecom Equipment Dissipates Heat…and Money

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San Diego, CA, United States

About EFFECT Photonics

About Jabil:

The multiple benefits of distributed access architectures

Distributing digital-analog conversion

Using DWDM in Remote PHY

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A Lower Upfront Investment

Economies of Scale and Operating Expenses

Working with the Best in the Business

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Size Matters

The Economics of Scale

Full Integration Streamlines Production and Testing

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Tell us a little more about yourself and the team

What attracted you to collaborate with EFFECT Photonics?

In what ways do the facilities of Aston University complement what EFFECT Photonics has?

What are some of the main challenges you hope to address?

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