Acacia was a pioneer of silicon photonics in 2012 when it was the first coherent module vendor to envision silicon as the platform for the integration of multiple discreet photonic functions while increasing the density and reducing cost of optical interconnect products. According to Gazettabyte, Acacia’s choice to back silicon photonics for coherent optics was an “industry trailblazing decision.”

Leveraging advancements in silicon photonics processing, Acacia was able to deliver generations of high-volume silicon photonics-based products that continually enabled higher transmission data rates, lower power, and higher performance than the generation before it. Early on, some skeptics dismissed silicon photonics as incapable of achieving the performance required for coherent optical transmissions over long-haul distances. As evidenced by today’s deployments of Acacia’s 1.2T multi-haul AC1200 coherent optical module in well over a hundred customer networks which include subsea, long-haul, regional, metro and DCI applications, it is clear that silicon photonics can achieve industry leading performance.

Today, Acacia’s solutions leveraging silicon photonics are available in a wide range of coherent optical interfaces, from edge and access to subsea applications, to enable high-speed transmission and excellent performance.

Acacia’s silicon photonics leadership timeline for coherent transmission.

The Power of Silicon Photonics

Using silicon as an optical medium and leveraging CMOS fabrication processing technology, silicon photonics allows tighter monolithic integration of many optical functions within a single device. While traditional optics systems used many discrete pieces, silicon photonics allows all those pieces to fit onto a single silicon chip.  This tight integration is what has allowed component vendors to continually drive reductions in the cost and size of optical solutions. For network equipment manufacturer customers, using the silicon photonics chip means they can design more ports per linecard, increasing the capacity of their system.

Below are a few reasons that silicon photonics has been so successful and has emerged as a key technology for existing and future optics solutions.

• Leverages CMOS Processes– Silicon photonics leverages the higher yields and lower cost associated with CMOS. Leveraging mature silicon process technologies means that much larger wafers can be made in silicon than traditional optics materials. Today’s silicon photonics solutions run on lines that accommodate up to 12-inch wafers or larger. These larger wafers result in an order of magnitude more dies per wafer, which lowers cost.
• Enables Package Level Integration – As the industry continues to move toward higher data rates and lower power, the interface between the DSP and high-speed optics is quickly becoming a bottleneck. Every time a high-speed signal needs to transition across an additional electrical interface (solder bumps, wire-bonds, vias, PCB traces) there is loss and distortion. Compensating for this additional loss adds power dissipation, and distortion limits performance. Using silicon photonics enables package-level integration that can better optimize these high-speed interfaces and accelerate the realization of higher data rates at lower power.  In addition, silicon photonics is temperature tolerant and thus is not affected by the heat-generating DSP.
• Ensures High Reliability –
  • Overall, silicon photonics increases reliability with the high level of integration reducing the number of component interconnects, which are a common source of failure
  • Traditional optics degrade in high-moisture environments, requiring optics to be packaged in costly hermetic gold boxes, which are historically one of the most common sources of failure for optics. Silicon, on the other hand, does not require hermiticity so by using silicon photonics the costly gold boxes are eliminated which improves reliability
  • In addition to having higher yields than traditional optics materials, silicon photonics can also be tested at the wafer level. Good die can be identified early in the process, and there is no labor wasted on material that will ultimately fail thereby reducing cost.
• Simplifies Deployment and Management – Pluggable modules with industry standard interfaces allow vendors to simplify their networks.

Higher baud rate designs

The next battle for the industry is achieving higher baud rates in a cost-effective way. As the gap to Shannon’s Limit narrows, it is becoming more difficult to increase channel capacity by increasing the modulation order while keeping the same transmission distance. This leaves higher baud rates as a preferred method to increase capacity and decrease cost per bit. Silicon photonics and advances in packaging technology enabled by silicon photonics are key for enabling higher baud rate designs.

Component Stacking

In component stacking, electrical impairments are reduced due to very short electrical connections between key RF components, creating a robust signal path for extremely high frequency/baud rate operation. In this stacked design, the gold-box packaging is eliminated, the DSP, and PIC are tightly co-packaged on the same substrate, and the high-speed modulator driver and TIA components are stacked on the PIC.  Stacked design has a higher (better) frequency response than the traditional gold-box design. Advanced stacking designs can further reduce interconnect impairments, resulting in even higher frequency response.

Illustration of example electrical interconnect frequency response comparing traditional gold-box and stacking integration shows that stacking provides a path to >100Gbaud.

New, Innovative Architectures and Future Innovations

Because of its ability to drive performance and volume manufacturability, silicon photonics has the potential to unlock new architectures needed to keep up with rising demand.  An example is pluggable coherent transceivers that can be plugged directly into switches and routers offering the same density for both coherent DWDM and client optics in the same chassis.  It can also drive future generations of optics design that push the envelope on performance, cost, complexity, and size.

The industry is now turning to silicon to produce a wide variety of devices, using mainstream silicon manufacturing process technologies that have matured over many years.  As optical transceivers need to support higher data-rate, driven by the demand for higher speed networks that can handle the rising bandwidth demand, we believe silicon photonics will once again allow the capacity to grow without significantly increasing the size and cost of the devices needed for the future. For this reason and the benefits discussed above, Acacia plans to use silicon photonics in all coherent applications going forward to help customers stay ahead of the curve.

OptiNet China takes place on the heels of OFC this year and its program will be focused on highlighting how optical networking, transport and DCI technologies are now more essential than ever to support and meet the growing needs of 5G, cloud services, and other major infrastructure projects. Throughout the two-day event, leading industry experts will discuss their latest developments.  One of the trends we expect to be discussed is coherent evolving towards shorter reach applications.

The Evolution is Real
Once considered a long-haul technology, coherent is now firmly entrenched in the metro and moving to even shorter reaches such as service provider edge/access and data center interconnect to campus and intra-data center.  Today’s coherent technology solutions offer a smaller footprint and lower power consumption driven by advancements in silicon photonics and by leveraging high-volume manufacturing processes from the electronics world and applying integration and co-packaging techniques.

As data rates are increasing from 400G to 800G and even 1.6T, these coherent solutions can provide the scalability, flexibility, operational simplicity, and cost advantages that network operators need to address their evolving network needs.  With a history of proven innovation in coherent optical interconnects and high-performance DSPs, Acacia offers a broad range of optical coherent solutions to meet the wide variety of needs of our customers. Check out our portfolio of product offerings at this link.

Come See us Speak
Fenghai Liu, Acacia’s Director of Product Line Management, will virtually present a session titled “Coherent Evolving to Shorter Reaches” on Day 2, June 17^th at 14:15 Beijing time. In his presentation, he will discuss how coherent solutions are evolving towards shorter reaches for intra data center applications.  You can find more information on Fenghai’s talk at this link or you can go directly to the OptiNet China program here.

If you are attending or just want to connect with one of our executives, click here to set up a meeting.

400G Pluggables Enter Deployment Phase
We are now seeing our service provider and hyperscaler customers preparing for an aggressive ramp to 400G services in the second half of 2021. They see significant opportunities to use coherent optics in switches and routers to simplify architectures and achieve reductions in CapEx and OpEx. In the last 6 months, there have been trial and testing announcements from Windstream Wholesale , Telia Carrier, and Colt highlighting the use of 400G pluggables in a carrier network environment. More recently, ADVA announced interoperability of Acacia’s high-performance coherent platform in a QSFP-DD form factor with ADVA’s new DCI OLS, providing DCI networks a clear path to a compact and cost-efficient optical layer assembled with best-in-class innovation. The success of these ongoing trials and tests have demonstrated the architectural benefits that 400G pluggables can provide to cloud data center interconnect (DCI) and service provider network operators.

Going Further Faster with High-Performance Embedded Solutions
Demand for high-performance embedded solutions continues to climb as network operators look for solutions that improve efficiency and maximize capacity utilization while reducing network cost.

To meet these requirements, next generation embedded coherent solutions should be able to maximize spectral efficiency and include features such as 150GHz-wide channels that double the channel bandwidth of current 75GHz. A 150GHz channel plan is important for accommodating higher aggregate baud rates (128Gbaud and beyond) that can expand 400G capacity over a much greater distance compared to 64Gbaud.

With their ability to operate beyond 100Gbaud, next-generation embedded solutions can allow network operators to evolve their networks to meet growing bandwidth demands, without sacrificing reach or stranding network bandwidth when migrating from current-generation solutions. SiPh opto-electronic integration and packaging are important tools for delivering this increased performance and functionality in the future.

Today, solutions such as Acacia’s Pico-based, AC1200 1.2 Terabit coherent optical module are meeting the needs of many markets including cloud, metro, long-haul, and submarine network applications by providing high performance and flexibility features required to address these demanding requirements.  In fact, the AC1200 module is deployed in more than one hundred networks around the globe and adopted by three of the four largest hyperscalers.

Coherent in Access Networks
The wired and wireless network infrastructure supporting today’s aggregated residential customer traffic and enterprise business services is driving bandwidth capacity higher than legacy infrastructure can support based on traditional optical transmission technology. While direct-detect solutions in service provider edge and access links encounter capacity and reach limitations, coherent technology can bridge the gap to higher bandwidth and longer distances on any deployed fiber type. Coherent also provides an operationally simple solution and comes in a range of form factors, such as QSFP-DD and CFP2, to address different network applications for cable, 5G wireless X-haul and enterprise services such as single-transmission P2P links, DWDM links, and single-fiber BiDi links. Read more in this white paper.

Come See us During OFC
This year we are excited to be participating in 6 panels that cover some of the key trends mentioned.

Here’s the full line up of Acacia speakers at this year’s show. On behalf of all our speakers below, we hope to see you there virtually.

• Status of Optoelectronics Multi-chip Modules in Acacia, Long Chen
  Sunday, June 6, 2021 1:00 PM – 3:30 PM PDT
• Market Watch Panel III: Terabit WDM Channels: Beyond 100GBaud Operation, Tom Williams
  Tuesday, June 8 14:30 – 16:00 PDT
• Challenges of Coherent Transponders Approaching the Shannon Limit, Christian Rasmussen
  Tuesday, June 8, 2021 14:00 PM – 16:00 PM PDT
• Next Generation Optical Interfaces, an IEEE and Industry Update, Tom Williams
  Wednesday, June 9 13:30 – 14:30 PDT
• 400ZR Deployment and What’s Next – an OIF Update, Tom Williams
  Friday, June 11 11:30 – 13:00 PDT
• Silicon Photonic Based Stacked Die Assembly for 4×200-Gbit/s Short-Reach Transmission, Ying Zhao
  Friday, June 11 6:00 AM PDT

Acacia will have a virtual booth (#1041) during the show, which you can access at this link.  We look forward to virtually meeting with our customers, partners, and suppliers.  We are also excited that this is Acacia’s first year participating as part of Cisco. You can find their virtual booth (#1441) at this link.

If you are attending the show virtually and want to connect, we’d welcome the opportunity to meet with you. Click here to set up a meeting with Acacia spokespeople.