To date, multiple system vendors have converged around Class 3-based solutions (Figure 1), recently announcing their next generation offerings. This industry convergence creates the benefit of economies of scale and broad industry investments into the technology used in this baud rate class, the same class being used for 800G MSA pluggable solutions.

Figure 1.  Acacia and other coherent vendors have announced Class 3 Terabit Era solutions.

Advancements Resulting in 65% Power-per-Bit Savings Over Current Competing Solutions
Doubling the baud rate from Class 2 to Class 3 in silicon was a significant engineering achievement, combining design advancements in high-speed Radio Frequency (RF) and Analog to Digital Converter (ADC) and Digital to Analog Converter (DAC) components plus well-designed co-packaging integration of silicon and silicon photonic (SiPh) components. These achievements led to Acacia’s successful 140Gbaud in-house capability that is being leveraged in the commercially available CIM 8 solution.

With high-volume shipments of multiple coherent Class 2 module products utilizing Acacia’s 3D Siliconization, this proven co-packaging integration solution provided the foundation for extending this capability to Class 3 140Gbaud implementation utilized in the CIM 8 (Figure 2). 3D Siliconization maximizes signal integrity by co-packaging all high-speed components including the coherent Digital Signal Processor (DSP) application-specific integrated circuit (ASIC), transmitter and receiver silicon photonics, and 3D stacked RF components into a single device that is manufactured in a standard electronics packaging house. Silicon technology has demonstrated cost and power advantages over alternative technologies, making it the material system of choice for these higher baud rates. These advancements enabling a doubling of the baud rate have led to a 65% power-per-bit savings of CIM 8 over current competing solutions that utilize alternative optical material systems. In addition, the size and power savings of this latest generation enabled the ability to house this 1.2T 140Gbaud solution in a pluggable form-factor.

Figure 2.  An example of 3D Siliconization used in the CIM 8 module, resulting in a volume electronics manufacturable high-speed single device larger than a quarter.

2^nd Generation 3D Shaping Advances Coherent Performance
The CIM 8 is powered by Jannu, Acacia’s 8^th generation coherent DSP ASIC. The design greatly expands on the success of the Pico DSP ASIC predecessor used in the widely deployed performance-optimized Class 2 AC1200 module (Figure 1). The AC1200 was the first module to introduce 3D Shaping, which provided finely tunable Adaptive Baud Rate up to 70Gbaud as well as finely tunable modulation up to 6 bits/symbol. The AC1200 had achieved record breaking spectral efficiency at the time of its introduction, as evidenced by a subsea trial over the MAREA submarine cable connecting Virginia Beach, Virginia to the city of Bilbao in Spain. Finely tunable baud rate helps maximize spectral efficiency in any given passband channel, converting excess margin into additional capacity/reach, and avoids wasted bandwidth due to network fragmentation.

Figure 3.  A popular feature is the fine-tunability of baud rate introduced by Acacia with the Class 2 AC1200; CIM 8 incorporates the same Adaptive Baud feature (as part of 2^nd Generation 3D Shaping) for Class 3 baud rate tunability.

The 5nm Jannu DSP ASIC in CIM 8 intelligently optimizes optical transmission using 2^nd Generation 3D Shaping with an increased Adaptive Baud Rate tunable range up to 140Gbaud, as well as finely tunable modulation up to 6 bits/symbol using enhanced Probabilistic Constellation Shaping (PCS). With 2^nd Generation 3D Shaping, the CIM 8 module can achieve a 20% improvement in spectral efficiency.

Terabit Era Solutions Provide Full Network Coverage
Class 3 technology not only ushers in the terabit era, but also enables full multi-haul network coverage as the high baud rate capabilities transport nx400GbE client traffic across a service provider’s entire network. Full network coverage is not only enabled by adjustment of the modulation, but also implies the capability to optimize for various network conditions which include overcoming transmission impairments.

Figure 4. CIM 8 1.2T, 1T, 800G, and 400G transmission constellations operating at Class 3 baud rates providing wide network coverage addressing multiple applications.

CIM 8 offers significant power-per-bit reductions as well as cost efficiencies for various optical network transport applications.

DCI/Metro Reaches
For transporting 3x400GbE or 12x100GbE client traffic with metro reaches in a single carrier, the CIM 8 is tuned to ~6 bits/symbol (equivalent to 64QAM, example constellation on left). Data center interconnect (DCI) applications would take advantage of this high-capacity 1.2T transport capability to tie data center locations together. This amounts to 38.4T per C-band fiber capacity.

Long-Haul Reaches

For transporting 2x400GbE with long-haul reaches, the CIM 8 is tuned to ~4 bits/symbol (equivalent to 16QAM, example constellation on the right). Wide 800G network coverage is achieved with the Class 3 140Gbaud capabilities enabling service providers to provide end-to-end 2x400GbE, 8x100GbE, or native 800GbE transport across their networks, covering essentially all terrestrial applications.

Ultra-Long-Haul/Subsea Reaches

And for ultra-long-haul/subsea reaches, the CIM 8 is tuned to ~2 bits/symbol (equivalent to QPSK, example constellation on the left). As with the previous scenarios, spectral efficiency with a wavelength channel is optimized by fine-tuning of the baud rate. These high spectrally efficient modes can carry mixed 100GbE and 400GbE traffic over the longest subsea routes in the world with lowest cost per bit. It’s worth noting that almost a decade ago, Acacia demonstrated SiPh capabilities for subsea coherent deployments. CIM 8 incorporates second generation non-linear equalization (NLEQ) capabilities to mitigate the non-linear effects of optical transmission especially for these ultra-long-haul/subsea links providing additional OSNR.

In all the above scenarios, the CIM 8 utilizes advanced power-efficient algorithms to compensate for chromatic and polarization dependent dispersion. In addition, the module accounts for coverage of aerial fiber network segments that require fast state-of-polarization (SOP) tracking and recovery due to lightning strikes. The SOP tracking speed of CIM 8 is double the speed of its predecessor. This fast SOP tracking feature can also be utilized for sensing applications.

Network Operators Achieve Record Breaking Field Trials with CIM 8
CIM 8 capabilities have already been put to the test as illustrated by multiple record breaking field trials across a wide range of applications. These include >5600km 400G transmission over a mobile carrier’s backbone network, 2200km 800G transmission over a research and education network, and >540km 1T transmission over a wholesale carrier’s network.

Acacia continues to demonstrate its technology leadership by leveraging mature knowledge in proven silicon-based coherent technology, producing the first shipping coherent solution to lead the industry into the Terabit Era with the 1.2T pluggable CIM 8 module. With the breakthrough capability of 140Gbaud transmission along with the advanced Jannu DSP ASIC using 2^nd Gen 3D Shaping and leveraging 3D Siliconization, network operators can support full network coverage for multi-haul applications, especially to support growing demands for nx400GbE and upcoming 800GbE traffic.

References:
Blog: Terabit Today: Maximize Network Coverage
Blog: How Industry Trends are Driving Coherent Technology Classifications
Blog Series: The Road Ahead for Next-Generation Multi-Haul Designs Part 1, Part 2, Part 3

Class 3 Baud Rate Solutions Provide Wide Network Coverage to Support nx400GbE
As widely known in the industry, the two primary “knobs” for optimizing coherent transmission capacity and reach are the baud rate and the bits/symbol modulation order. While rapid advances to increase capacity have pushed the upper modulation order to the current 6 bits/symbol (equivalent to 64QAM), further increases in modulation order provide incremental improvements in spectral efficiency with significant reductions in network coverage. Because of this, the industry focus to reduce cost and power consumption per bit has shifted toward achieving higher baud rate modulation per wavelength. Technology advancements that resulted in achieving 120+Gbaud coherent modulation speeds, as Figure 1 illustrates, have enabled a new generation of Class 3 capabilities which have propelled the industry from gigabit to terabit transmission capacity.

Figure 1. Achieving Class 3 baud rates enabled coherent transport solutions to break through the terabit threshold, ushered in by Acacia’s CIM 8 solution.

Terabit era performance-optimized solutions such as Acacia’s shipping Coherent Interconnect Module 8 (CIM 8), powered by the Jannu DSP, as well as announced solutions from several other optical transport vendors are now leveraging this Class 3 baud rate standardization. While this operating baud rate class enables a capacity of 1.2T for metro/DCI reaches, a key benefit is the ability to provide full network coverage at 800G to support transport of 2x400GbE clients, as shown in Figure 2. In addition, subsea applications can also be supported with greater flexibility to achieve optimal spectral efficiency. The flexibility, full coverage, and availability of these terabit era solutions make them attractive for supporting evolving transport needs as native 400GbE traffic requirements are becoming more commonplace.

Figure 2. Class 3 terabit era CIM 8 from Acacia provides 800G everywhere to transport 2x400GbE client traffic. By adjusting the transmission bits/symbol, a higher or lower number of 400GbE links can be achieved with corresponding reaches.

The CIM 8 achieves Class 3 140Gbaud rate capability using proven silicon technology to successfully break through the terabit-per-wavelength threshold. Silicon technology has demonstrated cost and power advantages over alternative technologies, making it the material system of choice for these higher baud rates. This module enables a coherent transmission solution capable of providing full network coverage to support nx400GbE traffic.

Terabit Era Solutions Support 400GbE Today, Ready for 800GbE in the Future
Supporting 400GbE client traffic over a network operator’s transport infrastructure is expected to be the dominant trend for many years to come. Terabit era solutions are ideal for these providers because they can implement a straightforward 2x scaling of channel spacing to evolve from Class 2 to Class 3 technology, as illustrated in Figure 1.

With full network coverage at 800G using ~4 bits/symbol transmission, the CIM 8 module can not only support today’s 2x400GbE client traffic, but it is also ready to enable 800GbE interconnections when that end-user demand materializes in the future.

With More than 65% Power-per-bit Savings, Why Delay on Achieving Power Reduction Goals?
CIM 8 takes advantage of Acacia’s most advanced silicon photonics technology that enables 140Gbaud capabilities resulting in doubling the capacity of each wavelength without doubling the component count, size, and power of the coherent device. In addition, advancements such as Acacia’s 3D Siliconization, which leverages highly integrated opto-electronic packaging, as well as the adoption of power-efficient signal processing algorithms, all contribute to a 65% power-per-bit savings of CIM 8 over current competing solutions being deployed.

With the industry striving to reduce overall power consumption, adoption of available solutions such as the Acacia CIM 8 can help towards achieving these goals sooner. Delaying the deployment of power saving technology on a network-wide scale can result in continued carbon emissions at current levels, delaying the achievement of power consumption reduction goals.

By incorporating coherent technology innovations to achieve low power Class 3 140Gbaud transmission while leveraging volume processes, CIM 8 is a result of the investments Acacia has made over generations of silicon-based products, providing a significant advantage for providers looking to drive long-term power-per-bit reductions without sacrificing performance and reach.

Maximizing Coverage for the Long-Term with Terabit Era Solutions
Network operators have multiple options to consider when migrating their infrastructures to support the growth of nx400GbE client traffic and preparing for 800GbE. While router-based optics solutions are gaining momentum, those wanting to maintain a transport optical layer are looking towards terabit era performance-optimized coherent solutions such as Acacia’s CIM 8 to support this growth. The CIM 8 module is shipping today and not only provides flexibility in supporting nx400GbE client traffic with wide network coverage, but also follows the direction of industry baud rate standards that allow for scalable network/channel-spacings as well as the utilization of mature silicon technology. This enables service providers to future proof their networks for traffic demands, while optimizing their return on investment and minimizing risk.

As generational gains in spectral efficiency, size and power become less significant, increasing baud rate is proving to be effective at significantly decreasing power per bit.

Performance Matters for Verizon as They Plan to Use Both Embedded and Pluggable Optics
Glenn Wellbrock, Director Optical Transport Planning for Verizon, talked about pluggables versus performance optimized (a.k.a. embedded) coherent modules, and how it’s important to leverage the volume that the hyperscalers are using to drive lower cost and power consumption. Glenn commented that the performance of the pluggable modules they’ve tested has exceeded their expectations. While they still plan to use performance optimized optics, they also plan to take advantage of pluggables anywhere they can because of the benefits they can provide in lower cost and power consumption.

Embedded Optics Used Primarily in Ultra Long-Haul Routes Operating Above 400G
On the performance optimized side, Glenn explained how it’s all about getting high performance, which by default usually means higher cost and proprietary implementations. He then went on to describe a field trial that Verizon completed where they were running embedded optics at maximum data rate for metro distances. They tested the same system at lower speeds for a long-haul route from New York to Chicago, demonstrating the benefits of a multi-haul solution. This proved that they could run 400G pretty much anywhere in the country.  Glenn also shared that on their long-haul networks, 80% is at or below 1,500km and 600G should be sufficient.

Verizon Plans to Continue Using Performance Optimized Embedded Optics for Ultra Long Haul
In the future, Glenn believes that both performance optimized optics and pluggables will continue to go up in performance. Today, the majority of Verizon’s new Ultra Long Haul (ULH) routes in its network are operating above 400G with embedded optics. According to Glenn, even if the next generation of optics gave Verizon 800G anywhere in the country with great performance, they would still want to know if they could get up to a Terabit or even 1.2T.  “If that will work on a lot of Verizon paths in a ULH environment, that is where Verizon is going to gravitate towards and it’s looking like that is going to happen with embedded optics,” added Glenn.

Acacia Sees Trends Influencing How Coherent Interfaces Should Be Developed
Tom Williams, Acacia’s Senior Director of Marketing, highlighted some of the key trends in the industry, starting with coherent moving to shorter reaches. This migration drives higher volumes as well as a need for more standardization because operators want the operational efficiency of interoperability and standards.

400ZR/ZR+ is exceeding expectations and is the fastest coherent product ramp ever displacing both proprietary coherent and direct detect solutions.

Tom recapped how 400ZR/ZR+ has exceeded expectations by being the fastest growing coherent ramp of all time. “We are seeing the core applications that drove the initial OIF 400ZR in the DCI use case and in many of those cases we saw MSA pluggables displacing performance optimized coherent and in others it replaced direct detect,” said Tom. “This has resulted in standardized pluggable optics taking up a higher portion of the coherent market.”

Tom also pointed out that during that same timeframe, the performance of embedded optics has scaled to the point where the industry is approaching the Shannon limit. As a result, component makers are now only seeing incremental improvements in spectral efficiency and operators are not getting significant improvement in capacity on the fiber. That has created a critical need to move to higher baud rates and higher data rates because they provide better economics and better power efficiency from optics. The most efficient way to do this is to develop high performance solutions that align with the investment that is already taking place in the shorter reaches in the pluggable space.

To illustrate the importance of taking the right steps with coherent development, Tom then described the path Acacia has taken. At each class, the company has developed both MSA pluggables and performance optimized solutions. Tom emphasized that, “The benefit that Acacia gets is that we make a big investment in each of these nodes, and we’ve been able to double the baud rate each time. We’ve seen the standards doing this and we’ve aligned our performance optimized solution with those standardized efforts.”  As an example, Acacia took the proven optics from the AC1200 operating at 70Gbaud and brought them into the company’s 400ZR/ZR+ products. Using the same platform allowed Acacia to then focus on advancing its packaging technology to take advantage of the efficiencies and have a scalable approach. And today, that same packaging technology is now feeding into the Coherent Interconnect Module (CIM) 8 module, which is enabling a pluggable performance optimized solution operating at 140Gbaud. It’s expected that the next generation will also have a doubling of the baud rates (as shown below) which would adhere to where the standards are expected to align.

Leveraging common development based on standards for both performance optimized, and pluggable solutions leads to higher data rates.

As Tom explained, the reason advancements in packaging have been so important is because the high-speed electrical interconnects are often the problem in the RF path when you start going to higher baud rates. By eliminating most of those interconnects, Acacia has been able to significantly extend the bandwidth of the RF chain and still get all the benefits of silicon and standards CMOS processes. Based on the Jannu DSP, the CIM 8 started shipping at the end of 2022 and has already been used in field trials with NYSERNet, China Mobile and Windstream Wholesale.

Nokia Looks to Lower Cost Per Bit with New Techniques
Serge Melle, Director Optical Product Marketing at Nokia, focused on what performance optimized solutions provide from a network applications standpoint. This started with a look at the trends that Nokia sees, and which are driving the key requirements for operators, which include bandwidth growth, faster internet speeds from IP routing platforms, and the need to lower network power consumption to achieve sustainability objectives.

As Serge stated, “This is really where this new generation of 5nm, 120Gbaud+ technology can address all of these things at the same time with the same technology evolution.” By being able to go to 1.2T wavelengths, operators can leverage the technology to achieve 2.4T in a single line card. That enables network operators to get much more scale in deployment of the bandwidth and reduce total cost of ownership, while also providing an effective means of transporting high speed services such as 400 Gigabit Ethernet and 800 Gigabit Ethernet. In addition, the performance improvement of this new generation of technology enables operators to triple the reach at 800G speeds – thereby going from several hundreds of kilometers to 2,000km distances at 800G per wavelengths.  Added Serge, “This is a very effective way to transport high-speed services across all network applications and can drive a significant reduction in the number of coherent optics needed in the network, which in turns leads to cost savings.  This technology can also provide significant network power savings because it can lower network power consumption by up to 60 percent.”

Like the prior speakers, Serge also stressed the importance of driving down the power per bit. “Every coherent generation has been able to achieve that and this latest generation of 1.2T technology continues the trend by leveraging 5nm silicon, silicon photonics and closer integration,” he said.

Finally, Serge shared how this latest generation of technology can be leveraged across a broad range of applications including metro DCI, long-haul and subsea networks.

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At the same time, network operators are adopting higher speed interfaces.  Since last year’s conference, we’ve continued to see the aggressive ramp of 400 Gigabits per second (G) pluggables as they’ve made their way into new markets and applications. While coherent pluggables have been migrating towards shorter reaches for quite some time, customers are now increasingly interested in using them for long-haul applications traditionally serviced by embedded coherent modules.  While the high-performance embedded market continues to be strong today, we expect the trend towards pluggables to continue in the future as service providers take advantage of their low power, small size and performance wherever they can.  Standards bodies are looking to define both 800G and higher performing 400G interop modes for next generation MSA pluggable optics.

Coherent pluggable ports are expected to exceed embedded ports in 2023.

 Acacia had the honor of participating in 13 sessions and 2 interoperability demonstrations at this year’s OFC.  Below is a recap of three of the sessions presented in the Market Watch Theater that reinforce the trends toward higher speed interfaces and expected transition from embedded modules to pluggables including industry standardization advancements.

OIF Panel: Defining 800ZR and 800LR; An OIF Update

Tom Williams, Acacia’s Sr. Director, Technical Marketing, gave an Optical Interoperability Forum (OIF) update on 800ZR and 800LR standardization progress. Tom highlighted the rapid success that has been achieved with 400G pluggables and what’s happening next in the standards bodies.

400G Developments Continue
The 400G developments continue in three areas.  The first is ongoing deployments of high transmit power 400G ZR+ QSFP-DD pluggables that support OpenZR+ and Open ROADM modes.  These modules expand the use cases for 400G QSFP-DD pluggables to metro and regional ROADM networks and enable increased transponder density in transport equipment. The second is 400G ER1 which targets 40km point-to-point applications.  The third area is standardization and development of 400G long-haul.

400G developments continue with high TX power 400G ZR+, 400G ER1, and 400G long haul pluggable modules.

800G Standardization in Progress
The current focus of standardization is on 800LR/ZR and Open ROADM products. Network operators are looking for higher baud rate pluggables to take advantage of improvements in cost and power. Increasing baud rates has become an efficient way to enable more cost-effective optical networks by reducing the number of optics needed to support a given transmission capacity.

Focusing next on 800ZR standardization, Tom highlighted how these considerations are like 400ZR, but different. While 800ZR has the potential for more varied use cases depending on the network operator, some are waiting for 1.6T solutions. The key assumptions are that 800ZR will include 16QAM modulation at 118Gbaud, which is double the 400ZR baud rate.  On the receiver side, Open Forward Error Correction, or oFEC, has been selected for improved Optical Signal to Noise Ratio (OSNR) sensitivity and the minimum input power is higher at 118Gbaud. On the transmitter side, there is recognition that the 400G market now includes both amplified and unamplified configurations and co-existence with 400ZR on the same line system requires 3dB higher transmit power for 800ZR.  Tom also highlighted three different transmitter power ranges that have been proposed with each option having use cases that bring value to the market.  These include:

• -11 to -14dBm: Lowest Cost
• -7 to -11dBm: Co-exist with 400ZR
• 0 to -7dBm: Co-exist with traditional DWDM

800G and Beyond Pluggable Coherent – Building on the Success of 400G

Torben Nielsen, Acacia’s Product Line Manager, Pluggable Modules and Distinguished Engineer, also kicked off his presentation by highlighting the 400ZR/ZR+ success story. As the fastest ramping coherent technology to date, these modules benefitted greatly from the work done early on with industry standards.

400G pluggables have been the fastest ramping coherent technology to date.

 Standardization and Vendor Interoperability
Standardization of optical networking technology helps network operators by providing simplicity, interoperability and volume-driven cost. Torben explained that, in the 400G pluggable market, standardization started with 400ZR and quickly evolved as carriers demanded higher performance. This led to the creation of both the Open ROADM and OpenZR+ MSAs.  As a result, today we are seeing 400G pluggables being used across a wide range of applications, using the same component technology throughout each form factor.

The 400ZR/ZR+ success story was enabled in part by standardization and interoperability resulting in 400G pluggables being used across a wide range of applications.  

Torben also discussed how 400ZR/ZR+ leveraged advancements in co-packaging and how these developments are now being extended to future product development using the same common platform that leverages silicon photonics. For example, the same packaging technology that Acacia used in its highly successful 400G pluggable products is now being utilized in its CIM 8 module, which is enabling a pluggable performance optimized solution operating up to 140Gbaud. Acacia will continue leveraging this same approach for future generations such as 800G and 1.6T modules.

800G Coherent Pluggables
Torben next shared how the industry is already looking ahead to 800G pluggables, with first deployments expected in 2024. Currently, 800ZR/LR is being defined in OIF, as Tom shared in his OIF update, with 118Gbaud 16QAM modulation. 800ZR+ will need standardized media interface specification which will likely be 131Gbaud PCS modulation.  Acacia’s silicon photonics can support all transmission rates proposed for both 800ZR and 800ZR+. The high transmit power version can be supported similar to the 400G Bright ZR+ high transmit (TX) power pluggable module.

800G will likely come in ZR, ZR+, and LR versions.

1.6T Coherent Pluggables
In terms of 1.6 coherent pluggables, Torben suggested they are likely needed in the 2025 timeframe or later. He believes 240Gbaud single carrier pluggable is feasible and can have the best potential cost structure with fewer optical components than multi-carrier approaches. There are several engineering challenges to overcome when developing these products including signal integrity, power and thermal design, but the industry has a great track record when it comes to overcoming these challenges.

1.6T coherent pluggables are expected to emerge in the 2025+ timeframe and much work is yet to be done for that to happen.

Market Watch Panel IV: Performance-Centric Long Haul

Anuj Malik, Acacia’s Director, Product Management & Strategy, gave an overview of performance-centric coherent modules. The primary goal of these modules has been to help reduce CapEx and OpEx for network operators. Transceiver cost per bit and number of regenerations are the key CapEx drivers.  Power, footprint and manageability are the key OpEx drivers.

Key to these solutions has been the development of features such as probabilistic constellation shaping (PCS), adaptive baud rate, and advanced compensation algorithms. These technology innovations give service providers unprecedented transmission flexibility to match their network’s architecture, optimize fiber utilization, and simplify deployment.

Performance-centric solutions leverage key technology innovations that provide “knobs” for dialing in performance. 

Anuj also discussed the implications of approaching the Shannon limit, where spectral efficiency gains are only incremental. The focus has been on reducing cost, power and footprint. This will require doubling the baud rate with every generation, designing efficient network architectures and leveraging the benefits of silicon photonics and advanced packaging techniques that can be leveraged across multiple generations of products.

The path to creating cost and power efficient coherent transceivers includes significant increases in capacity and density while reducing power, continued integration, and packaging techniques.

As mentioned earlier, these “terabit era” products were highlighted at this year’s OFC, led by Acacia’s CIM 8 module, with field trials having been announced by China Mobile, NYSERNet and Windstream Wholesale. By leveraging common development approaches with the 400G pluggable modules and Acacia’s proprietary DSP algorithms, the operational benefits of pluggability were brought to the performance-centric multi-haul market segment.  Acacia believes the industry may continue migrating performance-centric towards pluggable modules to take advantage of high performance and power efficiency. This may include the development of high performance 400G long haul pluggables and 800ZR+ with up to 131Gbaud.

Supporting data rates up to 1.2 terabits per second (1.2Tbps), the CIM 8 is the first commercial single optical carrier coherent transceiver that breaks into the “Terabit Era.” It is powered by Jannu, Acacia’s 8^th generation digital signal processor (DSP) ASIC, which is based on 5nm CMOS and features the latest in Silicon Photonic technology.  This solution delivers industry-leading performance in a small faceplate pluggable module by combining the Jannu DSP with 3D Siliconization packaging technology. The CIM 8 supports multi-haul applications by using second-generation 3D Shaping technology and continuous baud rate adjustment up to 140Gbaud, enabling customers to scale their networks efficiently and cost-effectively.

“The ability to maximize transmission data rate across a wide range of multi-haul network applications is key for cost-effectively scaling networks,” said Bill Gartner, SVP / GM Optical Systems and Optics Group at Cisco.  “Not only does the CIM 8 deliver exceptional performance, but it also consumes less than half the power per bit of competing solutions, allowing us to support terabit transmission with a small pluggable module.”

“Shipping CIM 8 Terabit Era optical transceivers with 140Gbaud capability to customers and seeing them tested in carrier networks is very exciting,” said Mehrdad Givehchi, VP of Engineering for Acacia. “Delivering the highest channel capacity and longest reach with maximum fiber utilization, the CIM 8 transceiver enables a wide range of multi-haul network applications including DCI, metro, long-haul, and subsea.”

Benefits of Increased Baud Rates

Increasing baud rate is an efficient way to enable more cost-effective optical networks by reducing the number of optics needed to support a given transmission capacity. By doubling the baud rate between successive generations, CIM 8 supports twice the capacity per carrier over greater reaches than earlier generations such as our widely deployed AC1200 coherent module. Three 400GbE client interfaces can be transmitted over virtually any network application, delivering 1.2Tbps per carrier capacity for high-capacity DCI interfaces, 800G per carrier capacity over most optical links using 4 bits/symbol (~16QAM) modulation and 400G QPSK over ultra-long-haul and subsea distances.

Performance Optimizing Features Enabled by the Jannu DSP

A key feature of the Jannu DSP is Acacia’s second-generation 3D Shaping technology, which includes advanced Probabilistic Constellation Shaping, Adaptive Baud Rate, and enhanced transmission impairment compensation algorithms providing superior performance using a single carrier implementation. This technology gives service providers unprecedented transmission flexibility to match their network’s architecture, optimize fiber utilization, simplify deployment, and save on both CAPEX and OPEX.

The Jannu DSP provides customers with continuous baud rate adjustment up to 140Gbaud and continuous modulation to optimize utilization of available spectrum in point-to-point DWDM or cascaded ROADM paths. As a single carrier design, the Jannu DSP incorporates Acacia’s most advanced line-rate processing algorithms to efficiently overcome fiber transmission impairments across various fiber types and fiber cable installation conditions. These power-efficient algorithms are designed to compensate fiber non-linearity to achieve longer transmission distance, automatically compensate for very large chromatic dispersion over trans-Pacific submarine cables, tolerate older deployed fibers with high Polarization Mode Dispersion, as well as provide fast state-of-polarization tracking required for aerial fiber cables in stormy weather conditions.

Leverages Acacia’s 3D Siliconization

The CIM 8 continues Acacia’s history of technology leadership by delivering industry leading performance based on the same silicon photonics used in high-volume pluggable modules. 3D Siliconization, a key enabler for the industry leading 140Gbaud, uses highly scalable and reliable volume semiconductor manufacturing processes, leveraging 3D stacking technology to enable a single packaged device to include all the high speed electrical and opto-electronic functions necessary for coherent transceivers. This device decreases footprint by integrating the DSP, Photonic Integrated Circuit, modulator drivers, and Transimpedance Amplifiers, and is manufactured using standard CMOS packaging processes that offer improvements in reliability, cost, and volume scaling.

To learn more, visit the Coherent Interconnect Module 8 page or contact us.

Supporting Resources

Acacia Unveils Industry’s First Single Carrier 1.2T Multi-Haul Pluggable Module

How Industry Trends are Driving Coherent Technology Classifications

The Road Ahead for Next Generation Multi-Haul Designs (Part 1 of 3)

The Road Ahead for Next Generation Multi-Haul Designs (Part 2 of 3)

The Road Ahead for Next-Generation Multi-Haul Designs (Part 3 of 3)

100GBaud+ Silicon Photonics Solutions Drive Optical Network Evolution

Introduction
In Part 2 of this blog series, I discussed how the approach of common development based on silicon photonics (SiPh) benefits both performance-optimized multi-haul and MSA pluggable coherent products. In this blog, I expand on why the adoption of standardized baud rates to support Nx400GbE client traffic has been advantageous for MSA pluggable adoption as well as for maximizing multi-haul 400G network coverage in a service provider network. I also discuss how the growth in coherent pluggable shipments impacts the development of performance-optimized multi-haul coherent solutions.

Intuitive Coherent Classifications
With 400GbE becoming today’s unit of traffic currency, it is important to understand what coherent operating conditions are required to efficiently transport 400GbE client traffic. Prior generation leading-edge modulation technology for commercialization was at ~60-68Gbaud (Class 2), which utilized ~4 bits/symbol (~16QAM) modulation to support 1x400GbE client traffic over a 400G wavelength. We saw OIF 400ZR, OpenZR+ MSA, and Open ROADM adopt this transmission scheme for high-volume MSA pluggable applications. Performance-optimized multi-haul coherent solutions also leveraged Class 2 baud rates with dynamic transmission shaping that was centered at ~4 bits/symbol. In addition, multi-haul solutions supported higher capacity with 6 bits/symbol (~64QAM) for shorter reach DCI/Edge applications as well as maximum reach using 2 bits/symbol (~QPSK) for subsea applications. Multi-haul coherent DSPs can dial up or down the desired bits/symbol transmission within this dynamic range.

Moving to the next generation of coherent solutions, a similar approach is being followed to support Nx400GbE traffic per wavelength. In this case, leading edge ~120-136Gbaud Class 3 modulation technology can double the transport capacity compared to Class 2. With Class 3 technology, and using ~4 bits/symbol range, near complete coverage of a service provider’s network with 2x400GbE traffic (800G per wavelength line rate transmission) is possible, as discussed in a previous blog. By dialing the modulation bits/symbol down to ~2 bits/symbol, 1x400GbE subsea applications are possible, while dialing up to ~6 bits/symbol, 3x400GbE client traffic can be transported over a 1.2T wavelength for shorter reach DCI/Edge applications.

Figure 1 shows the number of supported 400GbE clients that can be transported over a single coherent wavelength as a function of baud rate class and ~2, ~4, and ~6 bits/symbol values.

Figure 1. Matrix showing the number of supported 400GbE clients that can be transported over a single coherent wavelength as a function of bits/symbol and baud rate class. Broad Nx400GbE network coverage becomes possible as we move to Class 3 baud rate implementations.

Figure 1 also illustrates how doubling the baud rate maintains the same network coverage (vis-à -vis reach) while doubling the capacity. With performance innovations, the coverage at this doubled capacity may even be greater than the previous class.

Implications of Shipment Trends
The good news is that the technology investments that went into supporting Class 2 coherent pluggable MSA solutions (green-shaded cell in Figure 1) are coming to fruition with high-volume shipments already occurring. In fact, Acacia recently announced over 50k port shipments of 400G coherent pluggable solutions. This is contributing to a notable transition: the number of pluggable coherent modules shipments is forecasted to exceed that of performance-optimized (embedded) coherent module shipments (Figure 2).

What are the implications of the growing adoption of MSA pluggable solutions? The overarching implication for coherent design evolution is that standardization/industry consensus (e.g., baud rates), design elements (e.g., high-speed electrical components), as well as materials and processes (e.g., silicon, SiPh, CMOS processes, co-packaging) that support high-volume MSA pluggable solutions all have a favorable impact on performance-optimized multi-haul solutions. In Part 2, I went into detail about how a common silicon platform enables a cycle of coherent development. The Figure 2 data below indicates that given this growth in MSA pluggable ports, we should see a greater beneficial impact to performance-optimized multi-haul designs because higher volume pluggable solutions can lead to better cost efficiencies, assuming both the multi-haul and MSA pluggable designs leverage a common technology platform.

Figure 2. LightCounting data showing the number of globally shipped MSA pluggable coherent ports exceeding the number of proprietary form-factor ports.

The Road Ahead for Multi-Haul Solutions—CIM 8
As the industry moves towards supporting higher transmission line rates, a natural path to higher steps in baud rate are becoming clearer. Doubling the Class 2 baud rates aligns with the Class 3 120Gbaud+ rates that are being standardized for transport of 800G client traffic. By leveraging common silicon processes and technology, performance-optimized solutions can benefit from the economies of scale.

The recently announced Acacia Coherent Interconnect Module 8 (CIM 8) powered by Acacia’s Jannu DSP are in line with this approach. The CIM 8 is a performance-optimized multi-haul solution that delivers industry-leading performance with single carrier 1.2T operation using 3D Siliconization packaging technology that includes the silicon photonics integrated circuit (SiPh PIC), high-speed modulator driver and transimpedance amplifier (TIA) in a single opto-electronic package. The miniaturization of the module components has resulted in a 140Gbaud multi-haul module design capable of faceplate pluggability.

Figure 3. Acacia’s Coherent Interconnect Module 8 is designed to incorporate many aspects of technology leveraged from higher-volume products (e.g., SiPh, processes, components, packaging).

The CIM 8 can provide efficient transport of 400GbE client traffic across the entire network, including 90 percent coverage using 800G (2x400GbE client traffic), corresponding to the Class 3 row in Figure 1.

All Roads Lead to Multi-Haul

Figure 4. By utilizing common silicon technology, Acacia can leverage the advantages of volume and high-performance designs creating a generational development cycle, with advancements over time, that can result in cost efficiencies as well as time-to-market advantages.

Coherent solutions have evolved from long-distance applications at relatively moderate volumes and are now at a point in the road where shorter distance high-volume applications are driving a demand exceeding their long-distance counterparts. By leveraging standardized baud rates aligned with the corresponding bits/symbol modulation optimized for Nx400GbE, we can increase the overlap of silicon-based design and investments between high-volume MSA pluggable and performance-optimized multi-haul coherent solutions. This enhances the coherent cycle of development, resulting in multi-haul solutions benefiting from volume manufacturable designs while leveraging common technology, which are important for maintaining cost-efficiencies for network operators as bandwidth demand continues to grow.

Learn More About the Considerations Driving Next Generation Multi-Haul Solutions:

Part 2 of 3
Part 1 of 3

5G, video and cloud services are driving explosive bandwidth demand and network operators are challenged to scale capacity to meet this demand in a cost-effective and operationally simplistic way. To meet these needs, providers require multi-haul high-performance solutions that maximize their fiber investment, reduce power, simplify operations, and decrease costs. Multi-haul solutions can be used in applications ranging from high-capacity links between data center sites and metro and long-haul networks, as well as inter-continental submarine transmission.

Acacia’s performance optimized multi-haul coherent solutions have proven to be extremely effective at helping service providers meet these challenges. To date, Acacia has shipped more than 100,000 ports of its Pico Digital Signal Processor (DSP), which powers the company’s highly successful AC1200 1.2TB module. Customers appreciate the 3D Shaping capabilities including continuous baud rate adjustment available in the AC1200. Acacia’s Pico-based products are deployed in well over 100 networks across the globe and have been selected by 3 of the 4 largest hyperscalers.

Expanding the Performance Optimized Portfolio
Building on the success of the AC1200 and Pico DSP, the Coherent Interconnect Module 8 (CIM 8) is based on Acacia’s newest DSP technology, the 8^th generation Jannu 5nm CMOS DSP, and includes second generation 3D Shaping and continuous baud rate adjustment of up to 140Gbaud.  The new module is designed to achieve several industry firsts that separate it from competing solutions on the market:

• The first single-carrier 1.2TB multi-haul pluggable module
• The first coherent module to support 140Gbaud
• The first 5nm multi-haul DSP

“With over one hundred thousand ports shipped, Acacia’s Pico DSP is widely entrenched in networks around the globe and continues to provide network operators with a cost-effective way of scaling networks to meet rising bandwidth demands,” said Vlad Kozlov, Founder and CEO, LightCounting Market Research. “When complemented by the new CIM 8 module with the Jannu DSP, Acacia is able to offer service providers an arsenal of performance optimized coherent solutions that deliver maximum capacity for any network, at any distance and any passband.”

CIM 8 Awarded 5.0 in Lightwave Innovation Reviews
Each year, Lightwave Magazine holds its Innovation Reviews program where it evaluates and recognizes the most innovative products impacting the communications industry. This year, Acacia’s recently announced CIM 8 was not only recognized, but also scored the highest score of 5.0.  This perfect score is a testament to the innovation that the CIM 8 brings to the industry.  It’s important to note that in 2019, Acacia’s AC1200 also received a perfect score of 5.0.

Proven Technology Leadership and Vision
The newly introduced CIM 8 continues Acacia’s history of technology leadership by providing industry leading performance based on the same silicon photonics used in high volume pluggable modules. In addition, Acacia is leveraging the investments being made in next-generation standardized solutions. Aligning these developments helps Acacia to accelerate time to market for both standardized and multi-haul products and benefit from the combined scale.

For more information on Acacia’s high-performance optical coherent solutions, or to meet with us at OFC, contact us at this link.

Coherent Technology Evolution
We begin our series by reviewing the state of the industry and its impact on the evolution of coherent technology for supporting high speed optical transmission.

Multiple factors such as required bandwidth, technology capabilities, scalability, and cost should be considered by the industry to reach consensus on the next transmission data rate. These factors are explored and debated before investing dollars and resources into developing the solutions for the next generation. Ethernet, the dominant client protocol traffic type, has recently moved beyond 100 gigabit Ethernet (GbE) to current implementations at 400GbE, looking ahead towards 800GbE. To support these client traffic rates, coherent solutions also should provide optimal transport solutions for different distance applications with cost-efficiencies.

To achieve a targeted data rate over a single carrier, coherent designs utilize two key variables:  modulation order and baud rate. To transport 400GbE over DCI and metro links, industry consensus focused on utilizing 4 bits/symbol (~16QAM) at the Class 2 baud rate of 60-64Gbaud (corresponding to a 400G line rate). This allowed the design to meet the reach requirements for high-volume DCI and metro applications. As I expand on later in this blog series, this consensus is an important “stake in the ground” with respect to scaling to future coherent solutions and network architectures as bandwidth and client requirements continue to increase.

A Shift in Focus
Much has been written about how coherent DSP with algorithmic advancements over the years have resulted in narrowing the gap to the Shannon limit, the theoretical maximum information capacity within an optical channel. While each generation introduces innovations to improve performance, as the gap to the Shannon Limit narrows, the additional capacity achieved from digital signal processing power is becoming smaller. Thus, the industry has shifted its focus to increasing the baud rate per carrier, while also introducing performance-improving innovations, to enable end-users to achieve cost-efficiencies as bandwidth demand continues to grow. Newly introduced Class 3 120+Gbaud solutions based on silicon photonics offer a path to cost-effectively double capacity over a single carrier compared to current Class 2 implementations.

Moore’s Law
While the Shannon Limit informs us as to the maximum capacity allowed in an optical channel, the equally important Moore’s law predicts the trend for semiconductor industry transistor density to double approximately every two years helps to predict how coherent DSPs shrink in size and power consumption. This helped usher in generation after generation of increased functionality, size-reduced DSPs that can be leveraged for not only small sized transceiver form factors but also to support increasingly sophisticated algorithms for performance-optimized multi-haul transmission.

Photonic Integration
In 2014, Acacia introduced the first pluggable coherent module (CFP form factor) which laid the groundwork for future smaller pluggable modules, including the CFP2 and QSFP-DD multi-source agreement (MSA) form factors. Silicon photonics (SiPh), which uses semiconductor design tools and processes, played a key role in this evolution because of the benefits in size, power, cost, and yield. The miniaturization of the coherent DSPs along with SiPh technology enabled co-packaged designs to fit inside these compact MSA pluggable form factors. Performance-optimized multi-haul coherent solutions based on SiPh were able to leverage these miniaturized designs as well as silicon manufacturing processes.

These technology trends inform our decisions when we make investments in next generation coherent technology. One of Acacia’s strengths has been our ability to recognize technology shifts starting with the adoption of coherent to silicon photonics and pluggable DCO modules. We believe that a roadmap that is aligned with industry trends can best help network operators meet their growing bandwidth demands.

Learn More About the Considerations Driving Next Generation Multi-Haul Solutions

• Part 2 of 3
• Part 3 of 3