100ZR Archives - EFFECT Photonics

Insights

July 11, 2023

Where is 100ZR Needed?

Simply relying on traditional direct detect technologies will not meet the growing bandwidth and service…

Simply relying on traditional direct detect technologies will not meet the growing bandwidth and service requirements of mobile, cable, and business access networks, particularly regarding long-distance transmission. In many instances, deploying 100G coherent dense wavelength division multiplexing (DWDM) technology becomes essential to transmit larger volumes of data over extended distances.

Several applications in the optical network edge could benefit from upgrading from 10G DWDM or 100G grey aggregation uplinks to 100G DWDM optics:

Mobile Mid-haul: Seamless upgrade of existing uplinks from 10G to 100G DWDM.
Mobile Backhaul: Upgrading links to 100G IPoDWDM.
Cable Access: Upgrading uplinks of termination devices like optical line terminals (OLTs) and Converged Cable Access Platforms (CCAPs) from 10G to 100G DWDM.
Business Services: Scaling enterprise bandwidth beyond single-channel 100G grey links.

However, network providers have often been reluctant to abandon their 10G DWDM or 100G grey links because existing 100G DWDM solutions did not fulfill all the requirements. Although “scaled-down” coherent 400ZR solutions offered the desired reach and tunability, they proved too expensive and power-intensive for many access network applications. Moreover, the ports in small to medium IP routers used in most edge deployments do not support the commonly used QSFP-DD form factor of 400ZR modules but rather the QSFP28 form factor.

How Coherent 100ZR Can Move into Mobile X-haul

Figure-5gc-dwdm-midhaul — Figure 1: Simplified diagram of a DWDM link in the midhaul and backhaul of a mobile network.

The transition from 4G to 5G has transformed the radio access network (RAN) structure, evolving it from a two-level system (backhaul and fronthaul) in 4G to a three-level system (backhaul, midhaul, and fronthaul) in 5G:

Fronthaul: The segment between the active antenna unit (AAU) and the distributed unit (DU).
Midhaul: The segment from DU to the centralized unit (CU).
Backhaul: The segment from CU to the core network.

Figure-backhaul-fronthaul — Figure 2: Simplified diagram that shows and compares the building blocks of 4G (left) and 5G (right) access networks and the links between these blocks.

Most developed countries have already initiated the rollout of 5G, with many operators upgrading their 1G SFP transceivers to 10G SFP+ devices. Some of these 10G solutions incorporated DWDM technology, but many were single-channel grey transceivers. However, to advance to the next phase of 5G deployments, mobile networks must install and aggregate a greater number of smaller base stations to accommodate the exponential increase in connected devices.

These advanced stages of 5G deployment will necessitate operators to cost-effectively scale fiber capacity using more prevalent 10G DWDM SFP+ solutions and 25G SFP28 transceivers. This upgrade will pressure the aggregation segments of mobile backhaul and midhaul, which typically rely on link aggregation of multiple 10G DWDM links into a higher bandwidth group (e.g., 4x10G).

Figure 4x10G link aggregation — Figure 3: Comparison between 4x10G link aggregation and using a single coherent 100ZR link.

However, this type of link aggregation involves splitting larger traffic streams and can be intricate to integrate within an access ring. Adopting a single 100G uplink diminishes the need for such link aggregation, simplifying network configuration and operations. To gain further insight into the potential market and reach of this link aggregation upgrade, it is recommended to consult the recent Cignal AI report on 100ZR technologies.

Coherent 100ZR Uplinks Driven by Cable Migration to 10G PON

Figure-Fixed-Access-Uplinks-DWDM — Figure 4: Simplified diagram of a DWDM link between the coherent termination device (CTD) and the hub in a cable access network.

Cignal AI’s 100ZR report also states that the primary catalyst for 100ZR adoption will be the multiplexing of fixed access network links transitioning from 1G to 10G. This trend will be evident in the long-awaited shift of cable networks from Gigabit Passive Optical Networks (GPON) to 10G PON, driven by the new DOCSIS 4.0 standard. This standard promises 10Gbps download speeds for customers and necessitates several hardware upgrades in cable networks.

To multiplex these larger 10Gbps customer links, cable providers and network operators must upgrade their optical line terminals (OLTs) and Converged Cable Access Platforms (CCAPs) with 100G DWDM uplinks. Additionally, many of these new optical hubs will support up to 40 or 80 optical distribution networks (ODNs), making the previous approach of aggregating multiple 10G DWDM uplinks insufficient for handling the increased capacity and higher number of channels.

Anticipating these needs, the non-profit R&D organization CableLabs has recently spearheaded the development of a 100G Coherent PON (C-PON) standard. This proposal offers 100 Gbps per wavelength with a maximum reach of 80 km and a split ratio of up to 1:512. CableLabs envisions that C-PON, with its 100G capabilities, will play a significant role not only in cable optical network aggregation but also in other scenarios such as mobile x-haul, fiber-to-the-building (FTTB), long-reach rural areas, and distributed access networks.

Advancements in Business Services with 100ZR Coherent and QSFP28

Figure-cloud-DWDM — Figure 5: Simplified diagram of a DWDM link between a business and a cloud provider.

Nearly every organization utilizes the cloud in some capacity, whether for resource development and testing or software-as-a-service applications. However, leveraging the cloud effectively requires fast, high-bandwidth wide-area connectivity to ensure optimal performance of cloud-based applications.

Like cable networks, enterprises will need to upgrade their existing 1G Ethernet private lines to 10G Ethernet to meet these requirements, consequently driving the demand for 100G coherent uplinks. Cable providers and operators will also seek to capitalize on their upgraded 10G PON networks by expanding the reach and capacity of their business services.

The business and enterprise services sector was an early adopter of 100G coherent uplinks, deploying “scaled-down” 400ZR transceivers in the QSFP-DD form factor when they were the available solution. However, since QSFP-DD slots also support QSFP28 form factors, the emergence of QSFP 100ZR solutions presents a more appealing upgrade for these enterprise applications, offering reduced cost and power consumption.

While QSFP28 solutions had struggled to gain widespread acceptance due to the requirement for new, low-power digital signal processors (DSPs), DSP developers and vendors are now actively involved in 100ZR development projects: Acacia, Coherent/ADVA, Marvell/InnoLight, and Marvell/OE Solutions. This is also why EFFECT Photonics has announced its plans to co-develop a 100G DSP with Credo Semiconductor that best fits 100ZR solutions in the QSFP28 form factor.

Table Comparison QSFP-DD and QSFP-28. — Figure 6: Comparison between QSFP-DD and QSFP-28 form factors for 100G applications.

Takeaways

In the coming years, deploying and applying 100G coherent uplinks will witness increasing prevalence across the network edge. Specific use cases in mobile access networks will require transitioning from existing 10G DWDM link aggregation to a single coherent 100G DWDM uplink.

Simultaneously, the migration of cable networks and business services from 1Gbps to 10Gbps customer links will be the primary driver for the demand for coherent 100G uplinks. For carriers providing converged cable/mobile access, these uplink upgrades will create opportunities to integrate additional business services and mobile traffic into their existing cable networks.

As the ecosystem for QSFP28 100ZR solutions expands, production will scale up, making these solutions more widely accessible and affordable. This, in turn, will unlock new use cases within access networks.

Tags: 100G, 100G ZR, 100ZR, 10G, 10G PON, 5G, 5G deployment, aggregation, backhaul, bandwidth, business service, Business services, Cable access, cable networks, CCAP, Cloud connectivity, coherent, Coherent DWDM, Converged Cable Access Platforms (CCAPs), edge, Ethernet private lines, Fiber capacity, fronthaul, FTTH, IoT, Link aggregation, midhaul, mobile, mobile access network, mobile networks, Network providers, OLT, Optical line terminals (OLTs), PON, power, QSFP-DD, QSFP28, revenue, traffic, upgrade, uplink, Wide-area connectivity

Insights

April 5, 2023

Enabling a 100ZR Ecosystem

Given the success of 400ZR pluggable coherent solutions in the market, discussions in the telecom…

Given the success of 400ZR pluggable coherent solutions in the market, discussions in the telecom sector about a future beyond 400G pluggables have often focused on 800G solutions and 800ZR. However, there is also increasing excitement about “downscaling” to 100G coherent products for applications in the network edge. The industry is labeling these pluggables as 100ZR.

A recently released Heavy Reading survey revealed that over 75% of operators surveyed believe that 100G coherent pluggable optics will be used extensively in their edge and access evolution strategy. In response to this interest from operators, several vendors are keenly jumping on board the 100ZR train by announcing their development projects: Acacia, Coherent/ADVA, Marvell/InnoLight, and Marvell/OE Solutions.

This growing interest and use cases for 100ZR are also changing how industry analysts view the potential of the 100ZR market. Last February, Cignal AI released a report on 100ZR which stated that the viability of new low-power solutions in the QSFP28 form factor enabled use cases in access networks, thus doubling the size of their 100ZR shipment forecasts.

“The access market needs a simple, pluggable, low-cost upgrade to the 10G DWDM optics that it has been using for years. 100ZR is that upgrade. As access networks migrate from 1G solutions to 10G solutions, 100ZR will be a critical enabling technology.”
Scott Wilkinson, Lead Analyst for Optical Components at Cignal AI.

The 100ZR market can expand even further, however. Access networks are heavily price-conscious, and the lower prices of 100ZR pluggables become, the more widely they will be adopted. Reaching such a goal requires a vibrant 100ZR ecosystem with multiple suppliers that can provide lasers, digital signal processors (DSPs), and full transceiver solutions that address the access market’s needs and price targets.

The Constraints of Power in the Access

Initially, 100G coherent solutions were focused on the QSFP-DD form factor that was popularized by 400ZR solutions. However, power consumption has prevented these QSFP-DD solutions from becoming more viable in the access network domain.

Unlike data centers and the network core, access network equipment lives in uncontrolled environments with limited cooling capabilities. Therefore, every extra watt of pluggable power consumption will impact how vendors and operators design their cabinets and equipment. QSFP-DD modules forced operators and equipment vendors to use larger cooling components (heatsinks and fans), meaning that each module would need more space to cool appropriately. The increased need for cabinet real estate makes these modules more costly to deploy in the access domain.

Figure : Comparison between QSFP-DD and QSFP-28 form factors for 100G applications. — Figure 1 : Comparison between QSFP-DD and QSFP-28 form factors for 100G applications.

These struggles are a major reason why QSFP28 form factor solutions are becoming increasingly attractive in the 100ZR domain. Their power consumption (up to 6 watts) is lower than that of QSFP-DD form factors (up to 14 Watts), which allows them to be stacked more densely in access network equipment rooms. Besides, QSFP28 modules are compatible with existing access network equipment, which often features QSFP28 slots.

Ecosystems to Overcome the Laser and DSP Bottlenecks

Even though QSFP28 modules are better at addressing the power concerns of the access domain, some obstacles prevent their wider availability.

Since QSFP28 pluggables have a lower power consumption and slightly smaller footprint requirements, they also need new laser and DSP solutions. The industry cannot simply incorporate the same lasers and DSPs used for 400ZR devices. This is why EFFECT Photonics has announced its plans to develop a pico tunable laser assembly (pTLA) and co-develop a 100G DSP that will best fit 100ZR solutions in the QSFP28 form factor.

However, a 100ZR industry with only one or two laser and DSP suppliers will struggle to scale up and make these solutions more widely accessible. The 400ZR market provides a good example of the benefits of a vibrant ecosystem. Four vendors are currently shipping DSPs for 400ZR solutions, and even more companies have announced plans to develop DSPs. This larger vendor ecosystem will help 400ZR production scale up in volume and satisfy a rapidly growing market.

While the 100ZR market is smaller than the 400ZR one, its ecosystem must follow its example and expand to enable new use cases and further increase the market size.

Standards and Interoperability Make 100ZR More Widespread

Another reason 400ZR solutions became so widespread is their standardization and interoperability. Previously, the 400G space was more fragmented, and pluggables from different vendors could not operate with each other, forcing operators to use a single vendor for their entire network deployment.

Eventually, datacom and telecom providers approached their suppliers and the Optical Internetworking Forum (OIF) about the need to develop an interoperable 400G coherent solution that addressed their needs. These discussions and technology development led the OIF to publish the 400ZR implementation agreement in 2020. This standardization and interoperability effort enabled the explosive growth of the 400G market.

100ZR solutions must follow a similar path to reach a larger market. If telecom and datacom operators want more widespread and affordable 100ZR solutions, more of them will have to join the push for 100ZR standardization and interoperability. This includes standards not just for the power consumption and line interfaces but also for management and control interfaces, enabling more widespread use of remote provisioning and diagnostics. These efforts will make 100ZR devices easier to implement across access networks.

Takeaways

The demand from access network operators for 100ZR solutions is there, but it has yet to fully materialize in the industry forecasts because, right now, there is not enough supply of viable 100ZR solutions that can address their targets. So in a way, further growth of the 100ZR market is a self-fulfilled prophecy: the more suppliers and operators support 100ZR, the easier it is to scale up the supply and meet the price and power targets of access networks, expanding the potential market. Instead of one or two vendors fighting for control of a smaller 100ZR pie, having multiple vendors and standardization efforts will increase the supply, significantly increasing the size of the pie and benefiting everyone’s bottom line.

Therefore, EFFECT Photonics believes in the vision of a 100ZR ecosystem where multiple vendors can provide affordable laser, DSP, and complete transceiver solutions tailored to network edge use cases. Meanwhile, if network operators push towards greater standardization and interoperability, 100ZR solutions can become even more widespread and easy to use.

Tags: 100ZR, access networks, DSP, ecosystem, edge, laser, market, price, solutions

Insights

February 16, 2023

What DSPs Does the Network Edge Need?

Operators are strongly interested in 100G pluggables that can house tunable coherent optics in compact,…

Operators are strongly interested in 100G pluggables that can house tunable coherent optics in compact, low-power form factors like QSFP28. A recently released Heavy Reading survey revealed that over 75% of operators surveyed believe that 100G coherent pluggable optics will be used extensively in their edge and access evolution strategy.

These new 100G coherent pluggables will have very low power consumption (less than six Watts) and will be deployed in uncontrolled environments, imposing new demands on coherent digital signal processors (DSPs). To enable this next generation of coherent pluggables in the network edge, the next generation of DSPs needs ultra-low power consumption, co-designing with the optical engine, and industrial hardening.

The Power Requirements of the Network Edge

Several applications in the network edge can benefit from upgrading their existing 10G DWDM, or 100G grey links into 100G DWDM, such as the aggregation of fixed and mobile access networks and 100G data center interconnects for enterprises. However, network providers have often chosen to stick to their 10G links because the existing 100G solutions do not check all the required boxes.

100G direct detect pluggables have a more limited reach and are not always compatible with DWDM systems. “Scaled down” coherent 400ZR solutions have the required reach and tunability, but they are too expensive and power-hungry for edge applications. Besides, the ports in small to medium IP routers used in edge deployments often do not support QSFP-DD modules commonly used in 400ZR but QSFP28 modules.

The QSFP28 form factor imposes tighter footprint and power consumption constraints on coherent technologies compared to QSFP-DD modules. QSFP28 is slightly smaller, and most importantly, it can handle at most a 6-Watt power consumption, in contrast with the typical 15-Watt consumption of QSFP-DD modules in 400ZR links. Fortunately, the industry is moving towards a proper 100ZR solution in the QSFP28 form factor that balances performance, footprint, and power consumption requirements for the network edge.

These power requirements also impact DSP power consumption. DSPs constitute roughly 50% of coherent transceiver power consumption, so a DSP optimized for the network edge 100G use cases should aim to consume at most 2.5 to 3 Watts of power.

Figure 1: Normalized power breakdown of the internal blocks of a 400ZR pluggable module. Although this breakdown may vary a bit among different vendors, the authors find it to be generally true for various DSP-based modules, both IM-DD and coherent. Source: R. Nagarajan et al., IEEE JLT (2021)

Co-Designing and Adjusting for Power Efficiency

Achieving this ambitious power target will require scaling down performance in some areas and designing smartly in others. Let’s discuss a few examples below.

Modulation: 400ZR transceivers use a more power-hungry 16QAM modulation. This modulation scheme uses sixteen different states that arise from combining four different intensity levels and four phases of light. The new generation of 100ZR transceivers might use some variant of a QPSK modulation, which only uses four states from four different phases of light.
Forward Error Correction (FEC): DSPs in 400ZR transceivers use a more advanced concatenated FEC (CFEC) code, which combines inner and outer FEC codes to enhance the performance compared to a standard FEC code. The new 100ZR transceivers might use a more basic FEC type like GFEC. This is one of the earliest optical FEC algorithms and was adopted as part of the ITU G.709 specification.
Co-Designing DSP and Optical Engine: As we explained in a previous article about fit-for-platform DSPs, a transceiver optical engine designed on the indium phosphide platform could be designed to run at a voltage compatible with the DSP’s signal output. This way, the optimized DSP could drive the PIC directly without needing a separate analog driver, doing away with a significant power conversion overhead compared to a silicon photonics setup, as shown in the figure below.

Figure 2: Comparison between the drive power and power consumption of three different PIC + DSP pairings: standard DSP with a silicon PIC, standard DSP with an InP PIC, and an optimized DSP with an InP.

Industrial Hardening for DSPs

Traditionally, coherent devices have resided in the controlled settings of data center machine rooms or network provider equipment rooms. These rooms have active temperature control, cooling systems, dust and particle filters, airlocks, and humidity control. In such a setting, pluggable transceivers must operate within the so-called commercial temperature range (c-temp) from 0 to 70ºC.

On the other hand, the network edge often involves uncontrolled settings outdoors at the whims of Mother Nature. It might be at the top of an antenna, on mountain ranges, within traffic tunnels, or in Northern Europe’s severe winters. For these outdoor settings, transceivers should operate in the industrial temperature range (I-temp) from -40 to 85ºC. Higher altitude deployments provide additional challenges too. Because the air gets thinner, networking equipment cooling mechanisms become less effective, and the device cannot withstand casing temperatures as high as they can at sea level.

Industrial Hardening: Coherent Goes Outdoors — Making an I-temp transceiver means that every internal component—lasers, optical engine, DSP—must also be I-temp compliant. Thus, it’s essential to specifically design DSPs that can reliably work within the I-temp range.

Takeaways

The network edge could benefit from switching their existing direct detect or grey links to 100G DWDM coherent. However, the industry needs more affordable and power-efficient transceivers and DSPs specifically designed for coherent 100G transmission in edge and access networks. By realizing DSPs co-designed with the optics, adjusted for reduced power consumption, and industrially hardened, the network edge will have coherent DSP and transceiver products adapted to their needs.

Tags: 100ZR, access network, co-design, controlled, edge, fit for platform DSP, InP, low power, pluggables, power consumption, power conversion, QSFP 28, QSFP-DD

Insights

January 18, 2023

Reaching a 100ZR Future for Access Network Transport

In the optical access networks, the 400ZR pluggables that have become mainstream in datacom applications…

In the optical access networks, the 400ZR pluggables that have become mainstream in datacom applications are too expensive and power-hungry. Therefore, operators are strongly interested in 100G pluggables that can house coherent optics in compact form factors, just like 400ZR pluggables do. The industry is labeling these pluggables as 100ZR.

A recently released Heavy Reading survey revealed that over 75% of operators surveyed believe that 100G coherent pluggable optics will be used extensively in their edge and access evolution strategy. However, this interest had yet to materialize into a 100ZR market because no affordable or power-efficient products were available. The most the industry could offer was 400ZR pluggables that were “powered-down” for 100G capacity.

By embracing smaller and more customizable light sources, new optimized DSP designs, and high-volume manufacturing capabilities, we can develop native 100ZR solutions with lower costs that better fit edge and access networks.

Making Tunable Lasers Even Smaller?

Since the telecom and datacom industries want to pack more and more transceivers on a single router faceplate, integrable tunable laser assemblies (ITLAs) must maintain performance while moving to smaller footprints and lower power consumption and cost.

Fortunately, such ambitious specifications became possible thanks to improved photonic integration technology. The original 2011 ITLA standard from the Optical Internetworking Forum (OIF) was 74mm long by 30.5mm wide. By 2015, most tunable lasers shipped in a micro-ITLA form factor that cut the original ITLA footprint in half. In 2021, the nano-ITLA form factor designed for QSFP-DD and OSFP modules had once again cut the micro-ITLA footprint almost in half.

Figure-Evolution-laser — Figure 1: Evolution of tunable laser form factors for coherent optics (2011-2021). Figure inspired from a picture in Laser Focus World.

There are still plenty of discussions over the future of ITLA packaging to fit the QSFP28 form factors of these new 100ZR transceivers. For example, every tunable laser needs a wavelength locker component that stabilizes the laser’s output regardless of environmental conditions such as temperature. Integrating that wavelength locker component with the laser chip would help reduce the laser package’s footprint.

Another potential future to reduce the size of tunable laser packages is related to the control electronics. The current ITLA standards include the complete control electronics on the laser package, including power conversion and temperature control. However, if the transceiver’s main board handles some of these electronic functions instead of the laser package, the size of the laser package can be reduced.

This approach means that the reduced laser package would only have full functionality if connected to the main transceiver board. However, some transceiver developers will appreciate the laser package reduction and the extra freedom to provide their own laser control electronics.

Co-designing DSPs for Energy Efficiency

The 5 Watt-power requirement of 100ZR in a QSFP28 form factor is significantly reduced compared to the 15-Watt specification of 400ZR transceivers in a QSFP-DD form factor. Achieving this reduction requires a digital signal processor (DSP) specifically optimized for the 100G transceiver.

Current DSPs are designed to be agnostic to the material platform of the photonic integrated circuit (PIC) they are connected to, which can be Indium Phosphide (InP) or Silicon. Thus, they do not exploit the intrinsic advantages of these material platforms. Co-designing the DSP chip alongside the PIC can lead to a much better fit between these components.

To illustrate the impact of co-designing PIC and DSP, let’s look at an example. A PIC and a standard platform-agnostic DSP typically operate with signals of differing intensities, so they need some RF analog electronic components to “talk” to each other. This signal power conversion overhead constitutes roughly 2-3 Watts or about 10-15% of transceiver power consumption.

Figure-dac grey blocks — Figure : Simplified diagram of the building blocks of a coherent transceiver in which the DSP drives the optical engine directly from its digital-to-analog converter (DAC). This setup can minimize the power conversion overhead of optical transceivers.

However, the modulator of an InP PIC can run at a lower voltage than a silicon modulator. If this InP PIC and the DSP are designed and optimized together instead of using a standard DSP, the PIC could be designed to run at a voltage compatible with the DSP’s signal output. This way, the optimized DSP could drive the PIC directly without needing the RF analog driver, doing away with most of the power conversion overhead we discussed previously.

Graph-DSP-power — Figure 3: Comparison between the drive power and power consumption of three different PIC + DSP pairings: standard DSP with a silicon PIC, standard DSP with an InP PIC, and an optimized DSP with an InP.

Optical Subassemblies That Leverage Electronic Ecosystems

To become more accessible and affordable, the photonics manufacturing chain can learn from electronics packaging, assembly, and testing methods that are already well-known and standardized. After all, building a special production line is much more expensive than modifying an existing production flow.

There are several ways in which photonics packaging, assembly, and testing can be made more affordable and accessible: passive alignments of the optical fiber, BGA-style packaging, and flip-chip bonding. Making these techniques more widespread will make a massive difference in photonics’ ability to scale up and become as available as electronics. To read more about them, please read our previous article.

Takeaways

The interest in novel 100ZR coherent pluggable optics for edge and access applications is strong, but the market has struggled to provide “native” and specific 100ZR solutions to address this interest. Transceiver developers need to embrace several new technological approaches to develop these solutions. They will need smaller tunable laser packages that can fit the QSFP28 form factors of 100ZR solutions, optimized and co-designed DSPs that meet the reduced power consumption goals, and sub-assemblies that leverage electronic ecosystems for increased scale and reduced cost.

Tags: 100 ZR, 100G, 100ZR, 400ZR, C-band, C-PON, coherent, DSP, filters, future proof, Korea, laser sources, O-band, Packaging, pluggable, roadmap, S-band

Insights

January 4, 2023

What is 100ZR and Why Does it Matter?

In June 2022, transceiver developer II‐VI Incorporated (now Coherent Corp.) and optical networking solutions provider…

In June 2022, transceiver developer II‐VI Incorporated (now Coherent Corp.) and optical networking solutions provider ADVA announced the launch of the industry’s first 100ZR pluggable coherent transceiver. Discussions in the telecom sector about a future beyond 400G coherent technology have usually focused on 800G products, but there is increasing excitement about “downscaling” to 100G coherent products for certain applications in the network edge and business services. This article will discuss the market and technology forces that drive this change in discourse.

The Need for 100G Transmission in Telecom Deployments

The 400ZR pluggables that have become mainstream in datacom applications are too expensive and power-hungry for the optical network edge. Therefore, operators are strongly interested in 100G pluggables that can house coherent optics in compact form factors, just like 400ZR pluggables do. The industry is labeling these pluggables as 100ZR.

A recently released Heavy Reading survey revealed that over 75% of operators surveyed believe that 100G coherent pluggable optics will be used extensively in their edge and access evolution strategy. However, this interest had not really materialized into a 100ZR market because no affordable or power-efficient products were available. The most the industry could offer was 400ZR pluggables that were “powered-down” for 100G capacity.

Graph 100G coherent pluggables — Figure 1. Distribution of responses to a Heavy Reading survey question: how important are 100G coherent pluggable optics for your edge/access evolution strategy? The sample was composed of 87 people who work for network operators worldwide and are involved in network planning or purchasing network equipment. Source: Heavy Reading

100ZR and its Enabling Technologies

With the recent II-VI Incorporated and ADVA announcement, the industry is showing its first attempts at a native 100ZR solution that can provide a true alternative to the powered-down 400ZR products. Some of the key specifications of this novel 100ZR solution include:

A QSFP28 form factor, very similar but slightly smaller than a QSFP-DD
5 Watt power consumption
C-temp and I-temp certifications to handle harsh environments

The 5 Watt-power requirement is a major reduction compared to the 15-Watt specification of 400ZR transceivers in the QSFP-DD form factor. Achieving this spec requires a digital signal processor (DSP) that is specifically optimized for the 100G transceiver.

Transceiver developers often source their DSP, laser, and optical engine from different suppliers, so all these chips are designed separately from each other. This setup reduces the time to market, simplifies the research and design processes, but comes with performance and power consumption trade-offs.

In such cases, the DSP is like a Swiss army knife: a jack of all trades designed for different kinds of optical engines but a master of none. DSPs co-designed and optimized for their specific optical engine and laser can significantly improve power efficiency. You can read more about co-design approaches in one of our previous articles.

Achieving 100ZR Cost-Efficiency through Scale

Making 100ZR coherent optical transceivers more affordable is also a matter of volume production. As discussed in a previous article, if PIC production volumes can increase from a few thousand chips per year to a few million, the price per optical chip can decrease from thousands of Euros to mere tens of Euros. Such manufacturing scale demands a higher upfront investment, but the result is a more accessible product that more customers can purchase.

Graph-cost-per-PIC — Figure 2: Modelling of photonic integrated chip (PIC) cost as a function of aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost. Source: Model and graph provided by Prof. Meint Smit, TU Eindhoven.

Achieving this production goal requires photonics manufacturing chains to learn from electronics and leverage existing electronics manufacturing processes and ecosystems. Furthermore, transceiver developers must look for trusted large-scale manufacturing partners to guarantee a secure and high-volume supply of chips and packages.

If you want to know more about how photonics developers can leverage electronic ecosystems and methods, we recommend you read our in-depth piece on the subject.

Takeaways

As the Heavy Reading survey showed, the interest in 100G coherent pluggable optics for edge/access applications is strong, and operators have identified use key use cases within their networks. In the past, there were no true 100ZR solutions that could address this interest, but the use of optimized DSPs and light sources, as well as high-volume manufacturing capabilities, can finally deliver a viable and affordable 100ZR product.

Tags: 100G coherent, 100ZR, DSP, DSPs, edge and access applications, EFFECT Photonics, Photonics

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Telecom/Datacom

Emerging Industries

DSP & FEC

Ultra Pure Light Sources

Ecosystems

Pluggable Modules – Direct Detect

Pluggable Modules – Coherent

Sub-Assemblies

ASICs

View All

Insights

Press Releases

In the News

Events

Careers

Knowledge Center

Company Info

Contact Us