coherent communication systems Archives

Insights

May 4, 2022

The Growing Market for Tunable Lasers

The world is moving towards tunability. The combination of tunable lasers and dense wavelength division…

The world is moving towards tunability. The combination of tunable lasers and dense wavelength division multiplexing (DWDM) allows datacom and telecom industries to expand their network capacity without increasing their existing fiber infrastructure. Furthermore, the miniaturization of coherent technology into pluggable transceiver modules has finally enabled the widespread implementation of IP over DWDM solutions.

Self-tuning algorithms have also made DWDM solutions more widespread by simplifying their installation and maintenance. Hence, many application cases—metro transport, data center interconnects, and even future access networks—are moving towards coherent tunable pluggables. The market for coherent tunable transceivers will explode in the coming years, with LightCounting estimating that annual sales will double by 2026. Telecom carriers and especially data center providers will drive the market demand, upgrading their optical networks with 400G, 600G, and 800G pluggable transceiver modules that will become the new industry standards.

Figure 1: Market forecast for coherent DWDM modules by data rate. Source: LightCounting Market Forecast Report (April 2021)

Same Laser Performance, Smaller Package

As the industry moves towards packing more and more transceivers on a single router faceplate, tunable lasers need to maintain performance and power while moving to smaller footprints and lower power consumption and cost. Due to the faceplate density requirements for data center applications, transceiver power consumption is arguably the most critical factor in this use case.

In fact, power consumption is the main obstacle preventing pluggables from becoming a viable solution for a future upgrade to Terabit speeds. Since lasers are the second biggest power consumers in the transceiver module, laser manufacturers faced a paradoxical task. They must manufacture laser units that are small and energy-efficient enough to fit QSFP-DD and OSFP pluggable form factors while maintaining the laser performance. Fortunately, these ambitious spec targets became possible thanks to improved photonic integration technology.

The original 2011 ITLA standard from the Optical Internetworking Forum (OIF) was 74mm long by 30.5mm wide. By 2015, most tunable lasers shipped in a micro-ITLA form factor that cut the original ITLA footprint in half. In 2021, the nano-ITLA form factor designed for QSFP-DD and OSFP modules has once again cut the micro-ITLA footprint almost in half. The QSFP-DD modules that house the full transceiver are smaller (78mm by 20mm) than the original ITLA form factor. Stunningly, tunable laser manufacturers achieved this size reduction without impacting laser purity and power.

Figure 2: Evolution of tunable laser form factors for coherent optics (2011-2021). Figure from Laser Focus World.

Versatile Laser Developers for Different Use Cases

The different telecom and datacom applications will have different requirements for their tunable lasers. Premium coherent systems used for submarine and ultra-long-haul require best-in-class lasers with the highest power output and purity. On the other hand, metro transport and data center interconnect applications do not need the highest possible laser quality, but they need small devices with lower power consumption to fit router faceplates. Meanwhile, the access network space looks for lower-cost components that are also temperature hardened.

Table 1: Summary of different use cases for high-performance tunable lasers.

These varied use cases provide laser developers with ample opportunities and market niches to provide fit-for-purpose solutions for. For example, a laser module can be set to run at a higher voltage to provide higher output power and reach for premium long-haul applications. On the other hand, tuning the laser to a lower voltage would enable a more energy-efficient operation that could serve more lenient, shorter-reach use cases (links < 250km), such as data center interconnects.

An Independent Player in Times of Consolidation

With the increasing demand for coherent transceivers, many companies have performed acquisitions and mergers that allow them to develop transceiver components internally and thus secure their supply. LightCounting forecasts show that while this consolidation will decrease the sales of modulator and receiver components, the demand for tunable lasers will continue to grow. The forecast expects the tunable laser market for the transceiver to reach a size of $400M in 2026.

Figure 3: Global Market sales for high-performance modulators and receivers as well as tunable lasers. (Historical Data and Forecast). Source: LightCounting Market Forecast Report (April 2021)

We can dive deeper into the data to find the forces that drive the steady growth of the laser market. As shown in Figure 4, the next five years will likely see explosive growth in the demand for high-purity, high-power lasers. The forecast predicts that the shipments of such laser units will increase from roughly half a million in 2022 to 1.4 million in 2026 due to the growth of 400G and 800G transceiver upgrades. However, the industry consolidation will make it harder for component and equipment manufacturers to source lasers from independent vendors for their transceivers.

Figure 4: Units sold in the global market for Tunable Lasers components: legacy, high-purity low-power, and high-purity high-power (Historical Data and Forecast). Source: LightCounting Market Forecast Report (April 2021)

This data indicates that the market needs more independent vendors to provide high-performance ITLA components that adapt to different datacom or telecom provider needs. Following these trends, at EFFECT Photonics, we are not only developing the capabilities to provide a complete coherent transceiver solution but also the nano-ITLA units needed by other vendors.

Takeaways

The world is moving towards tunability. As telecom and datacom industries seek to expand their network capacity without increasing their fiber infrastructure, the sales tunable transceivers will explode in the coming years. These transceivers need tunable lasers with smaller sizes and lower power consumption than ever. Fortunately, the advances in photonic integration are managing to fulfill these laser requirements, leading to the new nano-ITLA module standards. However, even though component and equipment vendors need these tunable lasers for their next-gen transceivers, the industry consolidation can affect their supply. This situation presents an opportunity for new independent vendors to supply nano-ITLA units to this growing market.

Tags: acquisition, coherent, coherent communication systems, coherent optical module vendor, coherent technology stack, datacenters, datacom, DWDM, high-performance, hyperscalers, independent, Integrated Photonics, lasers, noise, OEM, optical engine, optical transceivers, performance, photonic integration, Photonics, pluggables, power consumption, reach, self-tuning, Telecom, telecom carriers, Transceivers, tunable, tunable laser, tuneability, VARs, versatile

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.

Press Releases

March 8, 2022

EFFECT Photonics Acquires Coherent Optical Digital Signal Processing Business from Viasat

EFFECT Photonics to Become the Most Highly Vertically Integrated, Independent Coherent Optical Module Vendor San…

EFFECT Photonics to Become the Most Highly Vertically Integrated, Independent Coherent Optical Module Vendor

San Diego, United States America – Today at OFC (Optical Fiber Conference) 2022, EFFECT Photonics, a leading provider of highly integrated optical communication products is announcing that it signed a definitive agreement to acquire coherent optical digital signal processing (DSP) and forward error correction (FEC) technology as well as a highly experienced engineering team from global communications company, Viasat Inc. (NASDAQ: VSAT).

Viasat is a long-established player in DSP and FEC technology. With eight generations of design IP, they have a proven track record of delivering successful field deployments.

From this acquisition, EFFECT Photonics will now own the entire coherent technology stack of all optical functions, including a high-performance tunable laser, together with DSP and FEC. This will enable the Company to deliver on its ambition to make high performance coherent communications solutions widely accessible and affordable. Furthermore, it will enable longer term economic and environmentally sustainable communications due to the ability to deliver high-end performance and reach within a small footprint and with lower power consumption. This opens the way to drive coherent technology into new places, revolutionizing the way the world interconnects.

This transaction is expected to provide the following customer benefits:

EFFECT Photonics will be able to optimize the complete solution for any application addressing both existing challenges and new possibilities
With full ownership of the key optical, DSP and FEC functions, EFFECT Photonics can offer seamless integration, cost efficiency and security of supply
EFFECT Photonics will be an independent vendor able to offer a full portfolio of building blocks such as the tunable laser and DSP, and/or complete solutions, increasing the choice reduced by recent mergers and acquisitions in the industry

EFFECT Photonics has also secured an additional $20M in Series-C funding bringing the total to $63M. Additionally, pursuant to the DSP acquisition agreement, Viasat will be joining EFFECT Photonics’ Supervisory Board and hold a minority interest in the Company.

“This is a significant step in accelerating our ambition to make coherent optical communications ubiquitous and further drive our product portfolio growth. We look forward to welcoming the team of highly skilled and experienced design architects and engineers who will be joining us to drive the development of energy efficient, high performance and affordable coherent solutions.

With all the recent changes in the industry landscape, this means that EFFECT Photonics is the only independent vendor able to deliver both the active optical components and the DSP. This will offer the market more choice and the ability to source superior solutions“
James Regan, CEO EFFECT Photonics.

“Given the trend of the fiber optic communications industry towards consolidation to provide vertically integrated end-to-end solutions, we believe that combining Viasat’s assets and capabilities with the unique integrated photonics capabilities of EFFECT Photonics will create substantially more market opportunities and better products. By investing in this Netherlands-headquartered company, we will also further expand our presence in Europe and be able to partner with EFFECT to bring state-of-the-art integrated photonics to Viasat’s own customers.”
Russell Fuerst, business area leader and vice president, Viasat.

–End of press release–

About EFFECT Photonics

EFFECT Photonics delivers highly integrated optical communications products based on its Dense Wavelength Division Multiplexing (DWDM) optical System-on-Chip technology. The key enabling technology for DWDM systems is full monolithic integration of all photonic components within a single chip and being able to produce these in volume with high yield at low cost. With this capability, EFFECT Photonics is addressing the need for affordable DWDM solutions driven by the soaring demand for high bandwidth connections. EFFECT Photonics is headquartered in The Netherlands, with additional facilities in the UK, the US and Taiwan, and a worldwide network of sales partners. http://www.effectphotonics.com

About Viasat

Viasat is a global communications company that believes everyone and everything in the world can be connected. For more than 35 years, Viasat has helped shape how consumers, businesses, governments and militaries around the world communicate. Today, the Company is developing the ultimate global communications network to power high-quality, secure, affordable, fast connections to impact people’s lives anywhere they are—on the ground, in the air or at sea. To learn more about Viasat, visit: www.viasat.com, go to Viasat’s Corporate Blog, or follow the Company on social media at: Facebook, Instagram, LinkedIn, Twitter or YouTube.

Copyright © 2022 EFFECT Photonics. All rights reserved. Viasat, the Viasat logo and the Viasat signal are registered trademarks of Viasat, Inc. All other product or company names mentioned are used for identification purposes only and may be trademarks of their respective owners.

Tags: acquisition, coherent, coherent communication systems, coherent optical module vendor, DSP, FEC, forward error correction, high vertical integration, independent coherent optical module vendor, Integrated Photonics, optical digital signal processing, optical engine, tunable laser, Viasat

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Telecom/Datacom

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DSP & FEC

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Pluggable Modules – Direct Detect

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