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

Acacia is excited to be participating once again in person!  We expect a number of hot topics to be front and center at the show – from the path to coherent lite, interoperable 400ZR/ZR+ pluggables ramping, and of course high-performance multi-haul solutions.

Coherent Lite

Over the last year, the industry has been abuzz around a new effort called “coherent lite,” which is a simpler implementation of coherent transmission that is designed for use in short reach campus and intra-DC applications. It essentially removes the features required for traditional transport DWDM applications.

Coherent lite pluggables can provide a competitive cost structure at 800G and beyond, utilizing fewer lasers, while meeting campus and intra-DC requirements. This solution can be a candidate for applications typically addressed by IM-DD solutions. We believe this will be a hot topic at the show.

The Rise of Standardized 400G Pluggables

The 400G coherent pluggable market is one of the most important developments in optical networking today. According to Cignal AI’s 4Q21 Transport Applications Report, shipments of 400ZR/ZR+ modules are expected to triple in 2022 as cloud operators such as Microsoft, Amazon, and Google are joined by traditional network operators such as AT&T, Windstream, and COLT rolling out high volume deployments.  Similarly, LightCounting’s Market Forecast from April 2022 estimates that the opportunity for pluggables based on 400ZR and 800ZR technology will surpass $2.8 billion by 2027.

Clearly, interoperable standards have played a key role in the rapid growth of pluggables. Standardization helps carriers by providing simplicity, interoperability and volume-driven cost. This has helped increase demand. The aggressive ramp of these products has been faster than any previous coherent technology generation. Several OIF members including Acacia are set to showcase multivendor interoperability for critical networking technologies at ECOC 2022.

OIF’s 400ZR project is proving successful in facilitating new and simplified architectures for high bandwidth inter-data center interconnects and promoting interoperability among coherent optical module manufacturers including Acacia’s 400ZR QSFP-DD. This 400ZR interop demo shows a full implementation across an 80km DWDM ecosystem using multiple form-factor pluggable modules, 400GbE routers, a 75 GHz C-band open line system, and test equipment solutions from multiple vendors. The demo provides evidence of widescale 400ZR deployment readiness based on a broad ecosystem of interoperable solutions.

Acacia’s newest entrant to the pluggable module category is the high transmit power 400G pluggable, which we are calling our “Bright” module.  We recently introduced the Bright 400ZR+ QSFP-DD pluggable coherent optical module with high optical performance designed for seamless deployment in ROADM line systems. These modules are designed to expand the applications for this technology by addressing a variety of ROADM architectures such as those with colorless multiplexing. With greater than +1 dBm transmit optical power and high transmit OSNR, Acacia’s Bright 400ZR+ gives network operators more flexibility to address a range of brownfield and greenfield applications utilizing the high-density QSFP-DD form factor.

High-Performance Multi-Haul Solutions

While pluggables are becoming extremely popular for router-based solutions in DCI, metro and some long-haul applications, transponder-based solutions are still required for long-haul, ultra-long haul and subsea. Transponders that include multi-haul high-performance modules can help network operators maximize their fiber investment, reduce power, simplify operations, and decrease costs.

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. As an example, 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 earlier implementations.

Acacia’s performance optimized multi-haul coherent solutions have proven to be extremely effective at helping service providers meet these challenges.  Earlier this year, Acacia announced it had shipped more than 100,000 ports of its Pico DSP which powers the company’s highly successful AC1200 1.2TB module.

Building on this success, Acacia introduced its Coherent Interconnect Module 8 (CIM8), which is based on the company’s newest DSP technology, the 8^th generation Jannu 5nm DSP, and includes second generation 3D Shaping and continuous baud rate adjustment of up to 140Gbaud.  This new module achieves several industry firsts:

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

Acacia successfully demonstrated 140Gbaud performance with our high-performance silicon photonics at this year’s OFC 2022.

Speaking Sessions

To hear more about the topics discussed in this article, don’t miss our speaking sessions.

• Workshop: Adaptive everything! Do optical networks really need more flexibility?
  • Presentation title: 400ZR and OpenZR+: Enabling New Network Architecture Optimization
  • Speaker: Lorenzo Ghioni
  • Date/time:  Sunday September 18^that 9:15-9:25 am
• Market Focus Panel: Modules/Sub-Systems/Connectors/Line-Cards
  • Presentation title: Next Generation Coherent Interfaces: Standardized Pluggable vs Proprietary Multi-haul
  • Speaker: Tom Williams
  • Date/time: Tuesday September 20^that 10:00-10:25 am

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