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

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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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

The Growth of 400G Pluggables
LightCounting’s Market Forecast from October 2021 estimates that the opportunity for pluggables based on 400ZR and 800ZR technology will surpass $2.3 billion by 2026. Acacia is experiencing strong demand for its 400G products and is ramping quickly.

This is being driven by growing bandwidth demand that is putting pressure on cloud providers to increase the data center interconnects (DCI) that link their facilities around the globe. 400G pluggable modules represent a key architectural change in high-bandwidth data center interconnects because they can be plugged directly into switches and routers offering the same density for both coherent DWDM and client optics in the same chassis. Much has been written about how this architectural change helps network operators support their growing bandwidth demands in a more cost-efficient manner.

Service providers are embracing the same technology to address applications with greater reaches and more complex network architectures. Acacia is continuing to introduce product configurations that offer maximum flexibility for service providers to leverage common technology to scale their network capacity.

We believe 400G pluggable solutions including “coherent gray optics” will continue to expand and allow customers to address a wide range of applications for cloud DCI and service provider networks with interoperability support for 400ZR, OpenZR+, Open ROADM, and CableLabs.

Acacia experts are presenting in a few sessions on this topic if you’d like to hear more:

Show Floor Program: Deployment of 400ZR and the Ongoing OIF Work to Define 800ZR/LR
Date/Time: Wednesday, March 9, 12:00 – 1:00 pm
Acacia Speaker: Tom Williams, Sr. Director of Marketing

Show Floor Program: OpenZR+: Enabling High-performance Router-based Optics
Date/Time: Thursday, March 10, 11:30 – 12:30 pm
Acacia Speaker: Tom Williams, Sr. Director of Marketing

Market Watch Panel V: Evolution of Coherent Transceiver Architectures for Specific Applications
Date/Time: Thursday, March 10, 10:30 – 12:00 pm
Acacia Speaker: Anuj Malik, Director of Product and Strategy

Performance Optimized Multi-Haul Solutions
Another hot topic continues to be ultra-high-performance multi-haul solutions.  The discussions around the importance of Silicon Photonics and roadmap alignment with industry trends continue.

Coherent technology innovations are helping service providers evolve their optical networks, optimize performance and lower cost per bit. To continue to advance, these providers need high-performance solutions that maximize their fiber investment, reduce power, simplify operations, and decrease costs.

To meet these needs, Acacia’s multi-haul coherent optical solutions work across multiple applications to help cost-effectively meet bandwidth needs. Acacia’s latest innovation, the Coherent Interconnect Module 8 (CIM 8) solution, is the industry’s first 1.2T pluggable coherent module designed to enable network operators to maximize transmission data rate across a wide range of multi-haul network applications including DCI, metro, long-haul, and subsea. In fact, the CIM 8 just received a 5.0 rating in the annual Lightwave Innovation Reviews.

If you’d like to learn more about the advancements in this area, we have several Acacia speakers sharing their expertise at these OFC sessions:

Workshop: Single-Carrier Versus Multi-Carrier for >800G Coherent Optics: A Revived Debate After a Decade
Date/Time: Sunday, March 6, 4:00 – 6:30 pm
Acacia Speaker: Ian Dedic, Distinguished Engineer

Workshop: How will 200G (and beyond) per Lambda IM/DD Compete with Coherent Technology for Intra-DC Applications
Date/Time: Sunday, March 6, 4:00 – 6:30 pm
Acacia Speaker: Mark Heimbuch, Principal Engineer

Panel: What are the Parallelization Technologies for Cost and Energy Efficient 1.6Tb Links?
Date/Time: Tuesday, March 8, 2:00 – 4:00 pm
Acacia Speaker: Long Chen, Director of Engineering

Panel: 1.6T SiPh Coherent Solution for Intra data Center Interconnection
Date/Time:  Tuesday, March 8, 2:00 – 4:00 pm
Acacia Speaker:  Hongbin Zhang, Principal Engineer 

Acacia Participating in First-Ever Public Multivendor 400ZR Interop Demo
Acacia’s 400ZR QSFP-DD and 400G CFP2 Pluggable Coherent Optical Modules will be used in the Optical Internetworking Forum Interoperability Demonstration to showcase progress on 400ZR.   OIF’s 400ZR project is critical in facilitating the reduction of cost and complexity for high bandwidth data center interconnects and promoting interoperability among optical module manufacturers. This is the first-ever public multivendor 400ZR interop demo. The demo consists of a full implementation of 400GE across an 80km, DWDM ecosystem using multiple modules, router, open line systems, and test equipment vendors, demonstrating the project achieved its interoperability goals.  You can see the demo at OIF’s booth, #5101.

Come See Us!
If you are attending the show and want to connect in person or virtually, we’d welcome the opportunity to meet with you. Click here to set up a meeting.  We hope to see you in San Diego!

That means 1) knowing what traffic granularity they need to transport and then 2) scaling the capacity in their transport network so that it aligns with the traffic granularity they need to move.

In addition, operators are looking for a common solution that can maximize network capacity over the widest network coverage. This can provide the ability to scale to higher capacity in a cost-effective way.

400GbE is Today’s Unit of Currency
Networks are evolving from 100GbE to 400GbE dominant traffic. As Telia Carrier stated, “400G: it’s here and huge!.” Network operators now need to figure out a way to build their networks to best support 400GbE traffic. True multi-haul solutions have emerged to meet this need because they were designed to be a flexible solution for DCI, metro, long-haul and subsea applications. However, a multi-haul solution is only effective if it can carry the different types of traffic it needs to transport while maximizing the value of existing infrastructure and reducing operational costs.

Multi-haul solutions maximize fiber utilization and simplify deployment.

Modulation Order Drives Design Decisions
Class 2 implementations utilizing 4 bits/symbol (~16QAM) and 60-64Gbaud have been standardized in the industry because they address a wide range of DCI and service provider metro applications as networks transition to 400GbE. Multi-haul implementations allow even greater reaches using approximately 4 bits/symbol with shaping and higher gain forward error correction algorithms. Class 2 multi-haul products transport 400GbE clients over the majority of network applications using 4 bits/symbol, with the ability to dial down the modulation format to 2 bits/symbol for the most challenging ultra-long-haul links.

Looking to Class 3 multi-haul products, efficient transmission of 400GbE traffic can best be achieved by doubling the baud rate to 120-128Gbaud. This enables 4 bits/symbol transmission supporting 800G line rates and 2 bits/symbol supporting 400G line rates. In high-capacity edge applications, these Class 3 products can support up to 1.2T line rates. By aligning client traffic granularity with the modulation orders that can best support network applications, identifying the preferred baud rate for Class 3 implementations becomes straightforward.

The industry has standardized on Class 2 implementations utilizing 4 bits/symbol (~16QAM) and 60-64Gbaud for various 400G implementations that address a range of DCI and service provider network applications.

Maximizing Network Application Coverage
A recently introduced Class 3 multi-haul solution, Acacia’s Coherent Interconnect Module 8 (CIM 8), can address transmission of multiple 400GbE client interfaces over virtually any network application, delivering 1.2T per carrier capacity for high-capacity DCI interfaces, 800G per carrier capacity over most optical links using 4 bits/symbol (~16QAM) modulation, and 400G per carrier over long-haul and subsea links.

Leveraging actual data from representative networks, the below simulation shows that the CIM 8 can effectively address subsea applications with 400G links, long-haul and metro with regional 800G (2x400G) and DCI and metro networks with 1.2T.  This means that the CIM 8 can provide efficient transport of 400GbE client traffic across the entire network, including 90 percent coverage using 800G (2x400GbE client traffic).

Utilizing data from actual service provider networks, Acacia’s CIM 8 can provide ~90% 800G network coverage compared to <20% for ~96Gbaud systems.

Scaling Efficiently and Cost-Effectively Today and Tomorrow
Network operators are being challenged more than ever before to scale their networks efficiently and cost effectively. Key to achieving this is knowing what kinds of traffic they are transporting and then building the right system that can most effectively transport that traffic.

As we approach Shannon’s Limit, further improvement will come from going to higher baud rates, but in a cost-effective way. As this article has discussed, having one solution that can be leveraged across all the various applications can enable an efficient and cost-effective solution for network operators looking to scale their networks today and in the future.

1.2T Delivering Maximum Capacity, Reach & Fiber Efficiency

Acacia, now part of Cisco, is once again introducing a ground-breaking coherent solution with the industry’s first 1.2 terabits per second (1.2T) faceplate pluggable coherent module, highlighting a new 8th generation Coherent Interconnect Module family, powered by Acacia’s Jannu 5nm CMOS digital signal processor (DSP) ASIC. This solution delivers industry-leading performance with single carrier 1.2T operation and combines the Jannu DSP with 3D Siliconization packaging technology which includes the silicon photonics integrated circuit (SiPh PIC), high-speed modulator driver and transimpedance amplifier (TIA) in a single optoelectronic package.

The Jannu DSP is designed to offer network operators the ability to maximize transmission data rate across a wide range of multi-haul network applications including DCI, metro, long-haul and subsea. “By leveraging the latest 5nm CMOS process node and our advanced signal processing algorithms, we’re delivering exceptional performance with less than half the power per bit of competing solutions, enabling a pluggable deployment model,” says Christian Rasmussen, Sr. Director, DSP and Optics Engineering and Founder at Acacia.

The Industry’s Next Class of Coherent Interconnect

The architecture of the new Coherent Interconnect Module 8 (CIM 8) solution builds upon the success of the Acacia AC1200 product family and aligns closely with the latest client data rates and coherent industry standardization efforts. The CIM 8 is designed to enable network operators to double their transmission capacity over even greater reaches. For links requiring maximum capacity, the new module can provide 1.2T capacity over a single wavelength.

“Historically, Acacia has been a groundbreaker in advancing coherent technology, and the company continues to demonstrate a long-term vision for how multi-haul coherent optics should evolve over time,” said Dr. Scott Wilkinson, Lead Analyst for Optical Components at Cignal AI. “Acacia’s new Coherent Interconnect Module is a great example of market leadership. This solution is a logical next step following the widely adopted Pico DSP-based products and will provide pluggability that is attractive to both traditional and cloud operators.”

The below figure illustrates how coherent technology has evolved in response to growing bandwidth demands. Different baud-rate classes are grouped based on technological capabilities, industry standardization (such as OIF, IEEE, Open ROADM, OpenZR+ MSA, CableLabs, ITU) and common industry investments. As the below figure depicts, the next class of coherent optical products, Class 3, enables a doubling of baud rates from the current Class 2 technology. Class 2 products include both multi-haul embedded modules and 400G faceplate pluggables where the latter was driven by standardization efforts that drove heavy investments into products centered around 16QAM, 60+Gbaud per 75GHz channel transmission.

Throughout this evolution, it has been critical that each successive class provide network architecture compatibility to the previous class, primarily reach and channel width. Acacia’s Class 3 product will support 150GHz channels with double the capacity per carrier and longer reach than that of the previous class, providing a simple, scalable path that is compatible with the previous network architecture generation.

The CIM 8 family is a Class 3 solution that can address transmission of multiple 400GbE client interfaces over virtually any network application, delivering 1.2T per carrier capacity for high-capacity DCI interfaces and 800G per carrier capacity over most optical links using 4 bits/symbol (~16QAM) modulation.

Leading in Performance and Fiber Utilization

The Jannu DSP features Acacia’s second-generation 3D Shaping technology, which leverages enhanced probabilistic constellation shaping (PCS) algorithms and Adaptive Baud Rate, a feature introduced in Acacia’s Pico DSP and widely embraced by network operators. The Jannu DSP provides customers with continuous baud rate adjustment up to 140Gbaud to optimize utilization of available spectrum in a single-span or in cascaded ROADM paths. These 3D Shaping features give service providers unprecedented transmission flexibility to match their network’s architecture, optimize fiber utilization, simplify deployment, and save on both CAPEX and OPEX.

As a single carrier design, the Jannu DSP also includes Acacia’s advanced line-rate processing algorithms to efficiently overcome fiber transmission impairments over greenfield or brownfield fiber infrastructures. These power-efficient algorithms are designed to compensate for linear and non-linear impairments, as well as provide state-of-polarization (SOP) tracking with industry leading response times. In addition, the Jannu DSP leverages Acacia’s new innovative soft-decision error correction (SD-FEC) to further enhance performance.

Scaling Optical Network Architectures

Acacia has been working towards a clear vision of how to cost-effectively scale network capacity for many years. The Jannu DSP builds on the performance and architectural benefits that have made the Pico DSP such a successful Class 2 coherent solution, but with double the baud rate and enhanced performance that supports transmission up to 1.2T in 150GHz channels. With adaptive baud rate capabilities, the CIM 8 also offers maximum capacity over any reach and channel plan.

“Today is an exciting new milestone in Acacia’s history as we once again introduce an exciting new product that delivers the type of disruption needed to cost-effectively scale network capacity in the future,” said Mehrdad Givehchi, Sr. Director of Engineering for Hardware and Software and Founder at Acacia. “With every generation of product, we have been able to deliver higher transmission data rates, lower power consumption and higher performance and I am proud to see this new product carry on that legacy.”

Crossing the Pluggable Terabit Threshold with High-Density Integration

Acacia’s 3D Siliconization is a major contributing factor in how the CIM 8 can cross the terabit capacity threshold and support faceplate pluggable optics that simplify network deployment and maintenance. 3D Siliconization applies integration and 3D stacking packaging techniques to enable a single device to include all the high-speed optoelectronic functions necessary for coherent transceivers. This device decreases footprint by including the DSP, SiPh PIC, drivers, TIAs, and is manufactured using standard CMOS packaging processes that leverage the same reliability, cost, and volume scaling advantages. With 3D Siliconization, the high-speed RF interfaces are tightly coupled together, resulting in improved signal integrity for high baud rate signals.

The high-density packaging as well as an advanced high-speed modulator design provides superior frequency response that enables the 140Gbaud performance as explained in this white paper.

Acacia Technology Leadership and Vision

Transforming industry trends into a development strategy takes the kind of vision Acacia has repeatedly shown in driving the adoption of pluggable digital coherent optical (DCO) modules based on silicon photonics. However, Acacia’s silicon photonics expertise expands beyond just pluggable coherent solutions. As shown in the above figure, Acacia has previously introduced multi-haul products in previous classes. In fact, the AC400 Class 1 product was the first commercially deployed all silicon photonics-based coherent module for submarine applications and the silicon photonics-based AC1200 was the industry’s first Class 2 multi-haul solution. The newly introduced CIM 8 continues this 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.

Acacia was a pioneer of silicon photonics for coherent applications in 2012 when it was the first coherent module vendor to envision silicon as the platform for the integration of multiple discreet photonic functions, increasing the density and reducing cost of optical interconnect products.

“Acacia’s vision and technology leadership has enabled us to transform coherent transmission. Our pioneering role in silicon photonics has led to the introduction of industry leading coherent pluggable and multi-haul solutions,” said Benny Mikkelsen, CTO and Founder of Acacia. “With every new product introduction, we have delivered the right solution at the right time to help our customers meet their growing bandwidth demands, and this new product introduction is a culmination of this proven technology leadership.”

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

Acacia has many reasons to be excited about this year’s European Conference on Optical Communications (ECOC) and one of the top ones is demonstrating our new AC1200-SC² (SC ‘squared’) coherent module, the first single-chip coherent module to deliver 1.2 Terabit (1.2T) on a single-channel. Not only did we announce the details around the AC1200-SC² today, but we also had four customers participate in our press release by providing supporting quotes. Thank you to ADVA, Cisco, ECI Telecom, and ZTE for your continued support of our product innovations. Everything we develop is to make you and our other customers successful, and we’re proud to once again have the opportunity to help you solve your greatest optical networking challenges.

Powered by Acacia’s 1.2T Pico DSP chip, the AC1200-SC² was designed to enable network operators to support today’s 100GbE clients, as well as emerging 400GbE clients, across key network segments such as DCI edge, metro, long-haul and submarine in an efficient, scalable, and cost-effective manner. The module’s high-performance and flexibility make the AC1200-SC² module ideally suited for multi-haul applications ranging from high- capacity 1.2T DCI edge to the most challenging terrestrial and submarine networks that require 400G channels and QPSK modulation.

Optimize your Network

The AC1200-SC² leverages Acacia’s 3D shaping technology designed to optimize fiber capacity and reach by filling gaps in margin and spectrum. Fine-tune adjustment of the modulation order and baud rate

provides network operators with the ability to adapt the transmission characteristics to meet the requirements of both greenfield and brownfield deployments. Capable of adapting to any channel spacing up to 150 GHz, the AC1200-SC² provides network operators with a straightforward channel plan roadmap.

The single-chip, single-channel AC1200-SC² supports 3 x 400G transmission using 64QAM modulation for DCI edge applications, as well as 1 x 400G transmission using QPSK modulation for long-haul and submarine applications. This application flexibility facilitates network savings by enabling common hardware to address multiple deployment scenarios, including 100GbE/400GbE, as well as reducing the need for costly regeneration nodes for long-haul and ultra-long-haul links.

The software intelligent AC1200-SC² coherent module supports 1.2T in a footprint that is 40% less than the size of 5” x 7” modules supporting transmission speeds of 400G today.

Come See us at ECOC

If you are attending the show, we’d love to see you and show you a demonstration of our new AC1200-SC². To set up a meeting, contact us.

Once again, Acacia Communications will be heading to the beautiful city of Nice to attend and speak at Next Generation Optical Networking (NGON) and DCI World on May 21-23. It’s our 6^th year at this show, but this year is extra special because 2019 marks Acacia’s 10-year anniversary.

This provides the perfect opportunity to reflect on the company’s innovative track record, which has enabled coherent optical interconnect reductions in power, size and cost per 100G at a pace of approximately 40% per year. Through this continued innovation and working intimately with our customers, we have solved some of the toughest optical networking challenges in the industry. As we embark on Nice, we are thankful to have had the opportunity to help our customers succeed during the last 10 years, and we are excited about what we can do together in the future.

Also during the show, we are excited to have our own Tom Williams speak on a plenary panel titled “To the terabit & beyond – practicalities for coherent transmission.” He’ll be joined by executives from Cignal AI, Telecom Argentina, OIF and ADVA, and their discussion will center around current operational demands and the potential offerings to support adoption through strategies and technologies. Tom’s panel is scheduled for Wed. May 22nd at 9:30 am. If you want more info on what will be discussed, check out the session description.

Some of the other key topics to be discussed include the 5G evolution, reducing costs, increasing capacity, data center connectivity, network automation, pluggable networks and much, much more!

As always, Acacia’s goal is to deliver the products that help our customers win. Below are two prominent trends we are seeing in the industry and how we plan to help our customers participate in those application areas. We think these will be two hot topic areas at NGON and DCI World and we look forward to discussing these in detail with customers, carriers, partners, cloud providers and OEMs.

Multi-Haul Solutions

Customers are finding enormous benefit using coherent transmission with varying baud rates and modulation modes applicable to multiple types of networks as described in this video. Our AC1200 module, powered by Acacia’s Pico DSP, delivers the flexibility and industry leading performance customers need for these multi-haul applications. Delivering 2Tbps in a footprint 40% smaller than 5×7 modules supporting 400Gbps today, and supported by customer validation testing, the AC1200 has achieved significant industry momentum over the last year. Multiple network equipment manufacturers (NEMs,) including Cisco, ADVA, and ECI Telecom are currently introducing systems based on AC1200 and it was successfully used in the first 400G transmission across the 6,600km trans-Atlantic Marea Cable. The AC1200 also features an innovative 3D shaping technology that offers network operators the flexibility to customize the AC1200 transmission to their network requirements. All these features and more are what led to Lightwave Magazine awarding the AC1200 the highest score of 5.0 in its Lightwave Innovations Reviews Program this past March.

Edge and Access Applications

Coherent pluggables are evolving to the edge to solve capacity issues in network access and edge applications, enabling carriers to reduce CapEx/OpEx and increase reach. Acacia’s 100G/200G CFP2 module, incorporating our Meru DSP, offers simple integration and a pay as you grow commercial model. There’s also a lot of buzz around the 400G CFP2 and future 400G QSFP-DD and OSFP 400G pluggables utilizing the Optical Internetworking Forum (OIF) specification for 400ZR to address key applications such as point-to-point data center interconnect (DCI) and IP over DWDM.

We are looking forward to a great show this year and of course, we can’t wait to spend a few days at the stunning venue Palais des Congrès Nice Acropolis. If you are lucky enough to be attending the show, we’d love to meet with you, discuss the trends we highlighted above, or even toast to our 10-year anniversary at the annual beach party. Contact us and someone will get back to you to set something up.

You can also follow our updates from the show on Twitter @AcaciaComms or #NGON2019.

We look forward to seeing you in Nice!

Coherent transmission w/ varying baud rates and modulation modes applicable to multiple types of networks has been referred to as multi-haul, as described in the OFC 2018 Show Report. A ROADM-rich network design is typically attributed to traditional metro networks. However, with the rise of multi-haul capable coherent technology, the lines between what is considered metro and long haul are sometimes blurred. A previous blog post provided a brief tutorial of coherent optical communications and how it is applied to long-haul, DCI, and metro networks. I encourage you to read that post as it provides a good background for this blog post.

A benefit of coherent optical transmission is that the bandwidth capacity of a link can be increased by moving to a higher modulation order (e.g, from 2-bits/symbol QPSK to 4-bits/symbol 16QAM), as long as there is sufficient optical signal-to-noise ratio (OSNR) margin to overcome the resulting penalty. Acacia’s patented Fractional QAM (F-QAM) provides a higher level of granularity compared to traditional quantized integer-bits/symbol modulation orders, by enabling non-integer bits-per-symbol (e.g, 3.3 bits/symbol) modulation, to better optimize link capacity. Another adjustable “knob” to increase capacity is the transmission baud rate, which directly varies the spectral width of the signal. Similar to traditional quantized modulation orders, coherent technology has previously implemented quantized baud rates. However, these quantized baud rates may result in sub-optimal use of the available channel bandwidth—that is, the spectral width of the transmission does not fill up the channel’s available passband. Adaptive Baud Rate provides the granularity to enable increased optimization of the available passband. F-QAM and Adaptive Baud Rate are elements of the Acacia AC1200 coherent transponder module’s 3D shaping capability.

In a multi-haul network where optical transmission between end points may encounter numerous cascaded optical filters, one challenge is to spectrally optimize the optical transmission to fit within the aggregate passband of these filters from either fixed or reconfigurable add/drops of the network’s line system, as shown in Figure 1.

Figure 1. Spectrally quantized transmission may leave spectral gaps in aggregate passband.

As previously mentioned, quantized baud rates may not allow enough flexibility and granularity to fill up the passband. However, by using Adaptive Baud Rate, the capacity can be increased to more closely match the available spectrum within the aggregate passband of the cascaded filters with fine granularity, as shown in Figure 2.

Figure 2. Acacia’s Adaptive Baud Rate can optimize the spectral transmission to more closely match the available aggregate passband spectrum.

The aggregate passband of the cascaded filters contributes to the upper bound limit of capacity increase one can achieve in a multi-haul network optical link. In this case, I am not referring to the theoretical Shannon Limit. Rather, I am referring to the practical passband constraints that come from the implementation in a network of cascaded imperfect optical filter passbands due to variations of the filter conditions. Variations may become more prevalent if the optical transmission passes through a multi-vendor line system environment, a potential situation in a disaggregated network architecture. Having the ability to vary modulation and baud rate allows for maximal flexibility in optimizing the transmission to more closely match the line system’s available passband, as opposed to matching the line system to the terminal equipment’s optical characteristics.

As previously mentioned, Acacia’s 3D Shaping capability, as illustrated in Figure 3, enables the “dialing-in” of both modulation mode and baud rate.

Figure 3. Acacia’s 3D shaping capability enables optimization of link capacity and reach; shaping of spectral width is achieved using Adaptive Baud Rate. 

This capability equates to the ability of the optical transmission spectrally “molding itself” to the line system’s passband on a link-by-link basis. By using 3D Shaping, to a certain extent the coherent DWDM source can be decoupled from the line system since the optical transmission is optimized regardless of the pass band characteristics of the line system. This capability lends itself nicely to the disaggregation of terminal equipment and line systems.

Whether multi-haul networks use flexible ROADM architectures with flexible passbands or architectures with fixed grid spacing (50GHz, 75GHz, 100GHz), the AC1200 with 3D Shaping can be used to optimize capacity with any of these type of line systems.