access networks Archives - EFFECT Photonics

Insights

April 24, 2024

Transceiver Customization for Flexible Access Networks

Let’s be honest: not every optical network problem can be solved by scaling up capacity.…

Let’s be honest: not every optical network problem can be solved by scaling up capacity. It’s not always cost-effective, and it’s not always sustainable. Providers and operators who want to become market leaders must scale up while also learning to allocate their existing network resources most efficiently and dynamically. For example, they must monitor their network performance frequently, providing more energy and capacity to high-traffic links while reducing power and capacity in areas with little traffic. They must find hardware that fits the rest of their network devices to a tee instead of equipment that is over- or under-specified.

Operators usually change settings in the higher network layers to adjust their networks dynamically. For example, artificial intelligence in network layer management will become a major factor in reducing the energy consumption of telecom networks. However, as networks get increasingly complex, operators need more degrees of freedom and knobs to adjust. They must customize the network and physical layers to fit the network best.

Fortunately, the new generation of pluggable transceivers gives operators more customization options than ever to change physical layer settings and adapt to these changing and growing network requirements and use cases. In this article, we will provide examples from our own pluggable transceivers and NarroWave technology.

Customization for Remote Diagnostics and Management

NarroWave sets up a separate low-frequency communication channel between two modules. This channel allows the headend module to remotely modify certain aspects of the tail-end module, effectively enabling several remote management and diagnostics options.

For example, the operator can remotely measure metrics such as the transceiver temperature and power transmitted and received. These metrics can provide a quick and useful health check of the link. The headend module can also remotely read alarms for low/high values of these metrics.

Even after buying the module, our customers can customize several variables, such as the low/high transmitter power levels, NarroWave self-tuning variables, memory behavior when turning on/off, or also the temperature and power flags and alarms. Customers also have the freedom to rewrite administrative information such as the vendor name, organization unique identifier (OUI), serial and part numbers, and passwords to access certain memory registers. These features are useful for system integrators and OEM sellers.

Customization for Easier Installation

Some of our transceiver features are customizations that make installation tasks easier. For example, setting up a network sometimes requires fibers to be repatched, which creates a loss of signal (LOS). Our NarroWave procedures include a customizable Ignore LOS (in seconds) flag that holds up the self-tuning scan and allows operators to perform maintenance duties without causing error messages at the host equipment.

These remote diagnostics and management features can eliminate certain truck rolls and save more operational expenses. They are especially convenient when dealing with very remote and hard-to-reach sites (e.g., an underground installation) that require expensive truck rolls.

Customization for Energy Sustainability

To talk about the impact of transceiver customization on energy sustainability, we first must review the concept of performance margins. This number is a vital measure of received signal quality and determines how much room there is for the signal to degrade without impacting the error-free operation of the optical link.

In the past, network designers have played it safe, maintaining large margins to ensure a robust network operation in different conditions. However, these higher margins usually require higher transmitter power and power consumption. Network management software can develop tighter, more accurate optical link budgets in real time that require lower residual margins through the remote diagnostics provided by this new generation of pluggable transceivers. This could lower the required transceiver powers and save valuable energy.

Another related sustainability feature is deciding whether to operate on low- or high-power mode depending on the optical link budget and fiber length. For example, if the transceiver needs to operate at its maximum 10G speed, it will likely need a higher performance margin and output power. However, if the operator uses the transceiver for just a 1G link, the transceiver can operate with a smaller residual margin and use a lower power setting. The transceiver uses energy more efficiently and sustainably by adapting to these circumstances.

Takeaways

Thanks to the advances in photonics and electronic integration, the new generation of pluggable transceivers has packaged many knobs and variables that previously required additional, specialized hardware that increased network complexity and costs. These advances give designers and operators more degrees of freedom than ever.

There are customizations that enable simpler remote management and diagnostics or easier installations. There are also customizable power settings that help the transceiver operate more sustainably. These benefits make access networks simpler, more affordable, and more sustainable to build and operate.

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Tags: access networks, alarms, capacity, channel, cost-effective, customization options, customize, dynamically, EFFECT Photonics, efficiently, electronic integration, energy sustainability, fiber length, hardware, health check, high-traffic links, installation tasks, low-traffic areas, management, metrics, NarroWave technology, network devices, network management software, network resources, operational expenses, operators, optical network, performance margins, Photonics, Pluggable Transceivers, power, power consumption, providers, remote diagnostics, remote sites, Scaling up, Signal degradation, Sustainable

Insights

April 10, 2024

Making Smaller Lasers at a Big Scale

The world is moving towards tunability. The combination of tunable lasers and dense wavelength division…

The world is moving towards tunability. The combination of tunable lasers and dense wavelength division multiplexing (DWDM) allows datacom and telecom industries to expand their network capacity without increasing their existing fiber infrastructure. Furthermore, the miniaturization of coherent technology into pluggable transceiver modules has finally enabled the widespread implementation of IP over DWDM solutions.

With the increasing demand for coherent transceivers, many companies have performed acquisitions and mergers that allow them to develop transceiver components internally and thus secure their supply. LightCounting forecasts show that while this consolidation will decrease the sales of modulator and receiver components, the demand for tunable lasers will continue to grow. The forecast expects the tunable laser market for the transceiver to reach a size of $400M in 2026.

East Asia is a huge driver of the rising number of tunable lasers sales. With initiatives like the “Broadband China” strategy and significant investments in 5G and beyond, the demand for advanced optical components, including tunable lasers, has surged in China. Japan and South Korea have a long history of adopting early new optical telecom innovations. After all, Japanese companies are at the forefront of research and development in tunable laser technology, and South Korea has built highly future-proofed 5G networks that are ahead of the implementations in Europe and North America. To meet the demands of this region, the industry needs to improve at making highly integrated tunable lasers at scale.

Making New and Smaller Lasers

The impact of small and integrated lasers extends beyond mere size considerations; it crucially contributes to enhancing power efficiency. Smaller laser designs inherently operate at lower voltages and currents, offering improved heat dissipation and minimizing coupling losses. Photonic integration helps achieve these reductions, maximizing efficiency by consolidating multiple functions onto a single chip.

The journey towards 100G coherent technology in access networks requires compact and power-efficient coherent pluggables in the QSFP28 form factor and, with it, compact and power-efficient tunable lasers that fit this form factor.

This monolithic integration of all tunable laser functions allowed EFFECT Photonics to develop a novel pico-ITLA (pITLA) module that will become the world’s smallest ITLA for coherent applications. The pITLA is the next step in tunable laser integration, including all laser functions in a package with just 20% of the volume of a nano-ITLA module. The figure below shows that even a standard matchstick dwarves the pITLA in size.

EFFECT Photonics’ laser solution is unique because it enables a widely tunable laser for which all its functions, including the wavelength locker, are monolithically integrated on a single chip. This setup is ideal for reducing power consumption and scaling into high production volumes.

The Economics of Scale

As innovative as these new, small lasers can be, they will have little impact if they cannot be manufactured at a high enough volume to satisfy the demands of mobile and cloud providers and drive down the cost per device.

This economy-of-scale principle is the same one behind electronics manufacturing, and the same must be applied to photonics. The more optical components we can integrate into a single chip, the more can the price of each component decrease. The more optical System-on-Chip (SoC) devices can go into a single wafer, the more can the price of each SoC decrease.

Researchers at the Technical University of Eindhoven and the JePPIX consortium have done some modelling to show how this economy of scale principle would apply to photonics. If production volumes can increase from a few thousands of chips per year to a few millions, the price per optical chip can decrease from thousands of Euros to mere tens of Euros. This must be the goal for the optical transceiver and tunable laser industry.

Learning to Scale from Electronics

A key way to improve photonics manufacturing is to learn from electronics packaging, assembly, and testing methods that are already well-known and standardized. After all, building a new special production line is much more expensive than modifying an existing production flow.

One electronic technique essential to transfer into photonics is ball-grid array (BGA) packaging. BGA-style packaging has grown popular among electronics manufacturers over the last few decades. It places the chip connections under the chip package, allowing more efficient use of space in circuit boards, a smaller package size, and better soldering.

Another critical technique to move into photonics is flip-chip bonding. This process is where solder bumps are deposited on the chip in the final fabrication step. The chip is flipped over and aligned with a circuit board for easier soldering.

Figure 5: Simplified steps of the flip chip bonding process.

Takeaways

As the demand for data and telecommunication services surges globally, the industry is moving towards more compact, power-efficient, and scalable laser solutions that integrate all necessary functions on a single chip. With East Asia driving the demand for these advanced components through their ambitious broadband and 5G initiatives, the challenge now lies in applying the economies of scale principle from electronics manufacturing to photonics. This approach would dramatically reduce costs and enable the mass adoption of these technologies.

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Tags: 100G coherent technology, 5G Networks, access networks, acquisitions, ball-grid array, Broadband China strategy, Coherent technology, datacom, Dense wavelength division multiplexing, East Asia, economy-of-scale principle, EFFECT Photonics, electronics manufacturing, electronics packaging, Fiber Infrastructure, Flip-chip bonding, high production volumes, highly integrated tunable lasers, IP over DWDM solutions, JePPIX consortium, LightCounting forecasts, mergers, Network capacity, optical components, photonic integrated chip, photonic integration, Photonics, Pico-ITLA Module, Pluggable transceiver modules, power consumption, Power Efficiency, QSFP28 form factor, System-on-Chip devices, Technical University of Eindhoven, telecom industries, The world, transceiver components, tunable laser market, Tunable laser technology, tunable lasers, wafer, wavelength locker

Insights

March 27, 2024

What’s New Inside a 100G ZR Module?

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.

Smaller Tunable Lasers

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 OIF 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.

There are still plenty of discussions over the future of ITLA packaging to fit the QSFP28 form factors of these new 100ZR transceivers. EFFECT Photonics has developed a solution that monolithically integrates all tunable laser functions (including the wavelength locker) into a novel pico-ITLA (pITLA) module that will become the world’s smallest ITLA for coherent applications. The pITLA is the next step in tunable laser integration, including all laser functions in a package with just 20% of the volume of a nano-ITLA module. The figure below shows that even a standard matchstick dwarves the pITLA in size.

More Efficient DSPs

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.

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.

Industrial Temperature Ranges

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.

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 laser sub-assemblies and DSPs that can reliably work within the I-temp range.

Takeaways

The advent of 100G ZR modules addresses the industry’s need for more affordable and energy-efficient alternatives to implement coherent technologies in access networks. The drive towards miniaturization, exemplified by EFFECT Photonics’ development of the world’s smallest ITLA module, alongside DSP optimizations that minimize power conversion overhead, will help develop pluggables that meet the efficiency and footprint requirements of access networks. Furthermore, it’s necessary for these modules to operate across an I-temp range that can handle a variety of challenging environments in which these networks must operate.

These developments will help operators lay the groundwork for a new generation of coherent optical access networks.

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Tags: 100G ZR, access networks, coherent optics, Cost-effective solutions, Datacom applications, DSP optimization, Edge evolution, efficiency, energy consumption, Environmental challenges, Industrial temperature range, ITLA modules, miniaturization, network operators, Networking equipment, Optical Access Networks., Photonics, Photonics Integration, pluggables, Technology advancements, tunable lasers

Insights

March 6, 2024

Reducing the Cost per Bit in Access Networks

Every telecommunications provider has the same fundamental problem. Many decades ago, service providers addressed increased…

Every telecommunications provider has the same fundamental problem. Many decades ago, service providers addressed increased network demands by spending more money and buying more hardware. However, network operators cannot allow their infrastructure spending to increase exponentially with network traffic, because the number of customers and the prices they are willing to pay for mobile services will not increase so steeply. The chart below is one that everyone in the communications industry is familiar with one way or another.

Figure 1. Graphical depiction of the fundamental telecommunications cost problem. Traffic volume increases exponentially, but operator revenues do not. Therefore, operators cannot allow their costs to increase exponentially to meet the traffic demand.

Given this context, reducing the cost per bit transmitted in a network is one of the fundamental mandates of telecommunication providers. As the global appetite for data grows exponentially, fueled by streaming services, cloud computing, and an ever-increasing number of connected devices, the pressure mounts on these providers to manage and reduce this cost.

In access networks, where the end users connect to the main network, this concept takes on an added layer of importance. These networks are the final link in the data delivery chain and are expensive to upgrade and maintain due to the sheer volume of equipment and devices required to reach each end user.

This is why one of EFFECT Photonics’ main missions is to use our optical solutions to reduce the cost per bit in access networks. In this article, we will briefly explain three key pillars that will allow us to achieve this goal.

Manufacturing at Scale

Previously, deploying optical technology required investing in large and expensive transponder equipment on both sides of the optical link. The rise of integrated photonics has not only reduced the footprint and energy consumption of coherent transceivers but also their cost. The economics of scale principles that rule the semiconductor industry reduce the cost of optical chips and the transceivers that use them.

The more optical components we can integrate into a single chip, the more can the price of each component decrease. The more optical System-on-Chip (SoC) devices can go into a single wafer, the more can the price of each SoC decrease. Researchers at the Technical University of Eindhoven and the JePPIX consortium have done some modelling to show how this economy of scale principle would apply to photonics. If production volumes can increase from a few thousands of chips per year to a few millions, the price per optical chip can decrease from thousands of Euros to mere tens of Euros.

Figure 5: 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. — 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.

By integrating all optical components on a single chip, we also shift the complexity from the assembly process to the much more efficient and scalable semiconductor wafer process. Assembling and packaging a device by interconnecting multiple photonic chips increases assembly complexity and costs. On the other hand, combining and aligning optical components on a wafer at a high volume is much easier, which drives down the device’s cost.

Integration Saves Power (and Energy)

Data centers and 5G networks might be hot commodities, but the infrastructure that enables them runs even hotter. Electronic equipment generates plenty of heat, and the more heat energy an electronic device dissipates, the more money and energy must be spent to cool it down.

These issues do not just affect the environment but also the bottom lines of communications companies. Cooling costs will increase even further with the exponential growth of traffic and the deployment of 5G networks. Integration is vital to reduce this heat dissipation and costs.

Photonics and optics are trying to follow a similar blueprint to the electronics industry and improve their integration to reduce power consumption and its associated costs. For example, over the last decade, coherent optical systems have been miniaturized from big, expensive line cards to small pluggables the size of a large USB stick. These compact transceivers with highly integrated optics and electronics have shorter interconnections, fewer losses, and more elements per chip area. These features all lead to a reduced power consumption over the last decade, as shown in the figure below.

Figure 4: Coherent module size and power consumption evolution from OIF MSA line card modules to pluggable modules like CFP and QSFP. — Figure 3: Coherent module size and power consumption evolution from OIF MSA line card modules to pluggable modules like CFP and QSFP.

DWDM Gives More Lanes to the Fiber Highway

Dense Wavelength Division Multiplexing (DWDM) is an optical technology that dramatically increases the amount of data transmitted over existing fiber networks. Data from various signals are separated, encoded on different wavelengths, and put together (multiplexed) in a single optical fiber.

The wavelengths are separated again and reconverted into the original digital signals at the receiving end. In other words, DWDM allows different data streams to be sent simultaneously over a single optical fiber without requiring the expensive installation of new fiber cables. In a way, it’s like adding more lanes to the information highway without building new roads!

Optical fiber with DWDM Channels — Figure 4: Example of a bidirectional DWDM system. At the central office, transceiver modules pick different wavelength channels for transmission, and these channels are combined into a single fiber through a device called a multiplexer. A demultiplexer splits the wavelength channels into separate fibers and the receiving modules on the remote end. Since this is a bidirectional system, transmission can go opposite too, from the remote end to the central office.

The tremendous expansion in data volume afforded with DWDM can be seen compared to other optical methods. A standard transceiver, often called a grey transceiver, is a single-channel device – each fiber has a single laser source. You can transmit 10 Gbps with grey optics. Coarse Wavelength Division Multiplexing (CWDM) has multiple channels, although far fewer than possible with DWDM. For example, with a 4-channel CWDM, you can transmit 40 Gbps. DWDM can accommodate up to 100 channels. You can transmit 1 Tbps or one trillion bps at that capacity – 100 times more data than grey optics and 25 times more than CWDM.

While the upgrade to DWDM requires some initial investment in new and more tunable transceivers, the use of this technology ultimately reduces the cost per bit transmitted to the network. Demand in access networks will continue to grow as we move toward IoT and 5G, and DWDM will be vital to scaling cost-effectively. Self-tuning modules have also helped further reduce the expenses associated with tunable transceivers.

Takeaways

The escalating demand for data traffic requires reducing the cost per bit in access networks. EFFECT Photonics outlines three ways that can help achieve this goal:

Manufacturing at scale to reduce the cost of optical chips and transceivers
Photonic integration to lower power consumption and save on cooling cost
Dense Wavelength Division Multiplexing (DWDM) to significantly increase data transmission capacity without deploying new fiber

At EFFECT Photonics believes these technologies and strategies to ensure efficient, cost-effective, and scalable data transmission for the future.

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Tags: 5G Networks, access networks, communications industry, cost per bit, data transmission capacity, Dense-wavelength division multiplexing (DWDM), EFFECT Photonics, fiber networks, heat dissipation, infrastructure spending, Integrated Photonics, manufacturing at scale, mobile services, network demands, network traffic, Optical Chips, Optical solutions, Photonics, reducing, Semiconductor Industry, System-on-Chip (SoC) devices, telecommunications provider

The power of self-tuning access networks

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January 31, 2024

The Power of Self-Tuning Access Networks

Article first published 16th February 2022, updated 31st January 2024. 5G networks will use higher…

Article first published 16^th February 2022, updated 31^st January 2024.

5G networks will use higher frequency bands, which require the deployment of more cell sites and antennas to cover the same geographical areas as 4G while existing antennas must upgrade to denser antenna arrays. On the side of fixed access networks, the rise of Remote PHY architectures and Dense Wavelength Division Multiplexing (DWDM) will lead to a similar increase in the density of optical network coverage.

Installing and maintaining these new nodes in fixed networks and optical fronthaul links for wireless networks will require many new DWDM optical links. Even though tunable DWDM modules have made these deployments a bit easier to handle, this tremendous network upgrade still comes with several challenges. Typical tunable modules still require several time-consuming processes to install and maintain, and that time quickly turns into higher expenses.

In the coming decade, the winners in the battle for dominance of access networks will be the providers and countries with the most extensive installed fiber base. Therefore, providers and nations must scale up cost-effectively AND quickly. Every hour saved is essential to reach targets before the competition. Fortunately, the telecom industry has a new weapon in the fight to reduce time-to-service and costs of their future networks: self-tuning DWDM modules.

Plug-and-Play Operation Reduces Time to Service

Typical tunable modules involve several tasks—manual tuning, verification of wavelength channel records—that can easily take an extra hour just for a single installation. Repair work on the field can take even longer if the technicians visit two different sites (e.g., the node and the multiplexer) to verify that they connected the correct fibers. If there are hundreds of nodes to install or repair, the required hours of labor can quickly rack up into the thousands.

Self-tuning allows technicians to treat tunable modules the same way they do with grey transceivers. There is no need for additional training for technicians to install the tunable module. Technicians only need to follow the typical cleaning and handling procedures, plug in the tunable module, and once plugged, the device will automatically scan and find the correct wavelength.

This plug-and-play operation of self-tuning modules eliminates the additional time and complexity of deploying new nodes and DWDM links in optical access networks. Self-tuning is a game-changing feature that makes DWDM networks simpler and more affordable to upgrade, manage, and maintain.

Host-Agnostic and Interoperable

Another way to save time when installing new tunable modules is to let specialized host equipment perform the tuning procedure instead. However, that would require the module and host to be compatible with each other and thus “speak the same language” when performing the tuning procedure. This situation leads to vendor lock-in: providers and integrators could not use host equipment or modules from a third party. This lock-in adds an extra layer of complexity and gives providers less flexibility to upgrade and innovate in their networks.

*Figure 1: Short description and comparison of different approaches to DWDM tunable modules.*

Self-tuning modules do not carry this trade-off because they are “host-agnostic”: they can plug into any host device as long as it accepts third-party 10G grey optics. Just as technicians can treat a self-tuning module as grey, any third-party host equipment can do the same. This benefit is possible because the module takes care of the tuning independently without relying on the host.

Enabling Simpler Network Management

Self-tuning lies at the core of EFFECT Photonics’ NarroWave technology. To implement our NarroWave procedures, we add a small low-frequency modulation signal to the tunable module and specific software that performs wavelength scanning and locking. Since this is a process controlled via software and the added signal is very small, it has no impact on these transceivers’ optical design and performance. It is simply an additional feature that the user can activate. The figure below gives a simplified overview of how NarroWave self-tuning works.

Figure 2: Example of a point to (multi-)point system including NarroWave self-tuning. Each of the 10G SFP+ modules is a full C-band tunable covering ITU channels 12 to 61. This link uses a single fiber for full duplex DWDM transmission, with unique wavelengths for up- and downstream links. When powered up, the modules will scan through different wavelengths, but in this case only the ‘correct’ wavelengths of channels 56 and 60 will go through the mux/demux unit and into the receiver on the other end. That receiver will then acknowledge reception of the signal.

Since self-tuning software requires exchanging commands between modules across the network, it can also enable remote management tasks. For example, our NarroWave communication channel can also allow the operator’s headend module to have read-write control over certain memory registers of the tail-end module. This means that the operator can modify several module variables such as the wavelength channel, power levels, behaviour when turning on/off, all from the comfort of the central office.

In addition, the NarroWave channel also allows the headend module to read diagnostic information from the remote module, such as transmitter power levels, alarms, warnings, or status flags. NarroWave then allows the user to act upon this information and change control limits, initiate channel tuning, or clear flags. These remote diagnostics and management features avoid the need for additional truck rolls and save even more operational expenses. They are especially convenient when dealing with very remote and hard-to-reach sites (e.g., an underground installation) that require expensive truck rolls. Some vendors have made remote installation and management of these modules even more accessible through smartphone app interfaces.

Takeaways

With these advantages, self-tuning modules can help rethink how optical access networks are built and maintained. They minimize the network’s time-to-service by eliminating additional installation tasks such as manual tuning and record verification and reducing the potential for human error. They are host-agnostic and can plug into any third-party host equipment. Furthermore, tunability standards will allow modules from different vendors to communicate with each other, avoiding compatibility issues and simplifying upgrade choices. Finally, the communication channels used in self-tuning can also become channels for remote diagnostics and management, simplifying network operation even further.

Self-tuning modules are bound to make optical network deployment and operation faster, simpler, and more affordable. In our next article, we will elaborate on how to customize self-tuning modules to better fit the needs of specific networks.

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Tags: access networks, DWDM, fixed access networks, flexible, G.metro, Integrated Photonics, OPEX, optical transceivers, photonic integration, Photonics, pluggables, remote diagnostics, remote management, self-tuning, Smart Tunable MSA, Transceivers, tuneability

The Light Path to a Coherent Cloud Edge Banner

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May 18, 2023

Data Center Interconnects: Coherent or Direct Detect?

Article first published 15 June 2022, updated 18 May 2023. With the increasing demand for…

Article first published 15 June 2022, updated 18 May 2023.

With the increasing demand for cloud-based applications, datacom providers are expanding their distributed computing networks. Therefore, they and telecom provider partners are looking for data center interconnect (DCI) solutions that are faster and more affordable than before to ensure that connectivity between metro and regional facilities does not become a bottleneck.

As shown in the figure below, we can think about three categories of data center interconnects based on their reach

Intra-data center interconnects (< 2km)
Campus data center interconnects (<10km)
Metro data center interconnects (<100km)

Figure 1: Example of different data center interconnect (DCI) links. Intra-data center interconnects usually have lengths up to 2kms, campus interconnects up to 10km, and metro DCIs up to 100km, although there can be longer DCIs.

Coherent 400ZR now dominates the metro DCI space, but in the coming decade, coherent technology could also play a role in shorter ranges, such as campus and intra-data center interconnects. As interconnects upgrade to Terabit speeds, coherent technology might start coming closer to direct detect power consumption and cost.

Coherent Dominates in Metro DCIs

The advances in electronic and photonic integration allowed coherent technology for metro DCIs to be miniaturized into QSFP-DD and OSFP form factors. This progress allowed the Optical Internetworking Forum (OIF) to create a 400ZR multi-source agreement. With small enough modules to pack a router faceplate densely, the datacom sector could profit from a 400ZR solution for high-capacity data center interconnects of up to 80km. Operations teams found the simplicity of coherent pluggables very attractive. There was no need to install and maintain additional amplifiers and compensators as in direct detection: a single coherent transceiver plugged into a router could fulfill the requirements.

As an example of their success, Cignal AI forecasted that 400ZR shipments would dominate edge applications, as shown in Figure 2.

Figure 2: Forecast of 100G port equivalents shipped for edge applications. These shipments are overwhelmingly 400ZR standard technology. Source: Cignal AI Transport Applications Report Q42021. This plot is the most recent update that includes this 100G Equivalent Port data, but more updated Cignal AI reports with similar data can be found here. — Figure 2: Forecast of 100G port equivalents shipped for edge applications. These shipments are overwhelmingly 400ZR standard technology. Source: Cignal AI Transport Applications Report Q42021. This plot is the most recent update that includes this 100G Equivalent Port data, but more updated Cignal AI reports with similar data can be found *here*.

Campus Interconnect Are the Grey Area

The campus DCI segment, featuring distances below 10 kilometers, was squarely in the domain of direct detect products when the standard speed of these links was 100Gbps. No amplifiers nor compensators were needed for these shorter distances, so direct detect transceivers are as simple to deploy and maintain as coherent ones.

However, as link bandwidths increase into the Terabit space, these direct detect links will need more amplifiers to reach 10 kilometers, and their power consumption will approach that of coherent solutions. The industry initially predicted that coherent solutions would be able to match the power consumption of PAM4 direct detect solutions as early as 800G generation. However, PAM4 developers have proven resourceful and have borrowed some aspects of coherent solutions without fully implementing a coherent solution. For example, ahead of OFC 2023, semiconductor solutions provider Marvell announced a 1.6Tbps PAM4 platform that pushes the envelope on the cost and power per bit they could offer in the 10 km range.

Following the coming years and how the PAM-4 industry evolves will be interesting. How many (power-hungry) features of coherent solutions will they have to borrow if they want to keep up in upcoming generations and speeds of 3.2 Tbps and beyond? Lumentum’s Chief Technology Officer, Brandon Collings, has some interesting thoughts on the subject in this interview with Gazettabyte.

Direct Detect Dominates Intra Data Center Interconnects (For Now…)

Below Terabit speeds, direct detect technology (both NRZ and PAM-4) will likely dominate the intra-DCI space (also called data center fabric) in the coming years. In this space, links span less than 2 kilometers, and for particularly short links (< 300 meters), affordable multimode fiber (MMF) is frequently used.

Nevertheless, moving to larger, more centralized data centers (such as hyperscale) is lengthening intra-DCI links. Instead of transferring data directly from one data center building to another, new data centers move data to a central hub. So even if the building you want to connect to might be 200 meters away, the fiber runs to a hub that might be one or two kilometers away. In other words, intra-DCI links are becoming campus DCI links requiring their single-mode fiber solutions.

On top of these changes, the upgrades to Terabit speeds in the coming decade will also see coherent solutions more closely challenge the power consumption of direct detect transceivers. PAM-4 direct detect transceivers that fulfill the speed requirements require digital signal processors (DSPs) and more complex lasers that will be less efficient and affordable than previous generations of direct detect technology. With coherent technology scaling up in volume and having greater flexibility and performance, one can argue that it will also reach cost-competitiveness in this space.

Takeaways

Unsurprisingly, using coherent or direct detect technology for data center interconnects boils down to reach and capacity needs. 400ZR coherent is already established as the solution for metro DCIs. In campus interconnects of 10 km or less, PAM-4 products remain a robust solution up to 1.6 Tbps, but coherent technology is making a case for its use. Thus, it will be interesting to see how they compete in future generations and 3.2 Tbps.

Coherent solutions are also becoming more competitive as the intra-data center sector moves into higher Terabit speeds, like 3.2Tbps. Overall, the datacom sector is moving towards coherent technology, which is worth considering when upgrading data center links.

Tags: 800G, access networks, coherent, cost, cost-effective, Data center, distributed computing, edge and metro DCIs, integration, Intra DCI, license, metro, miniaturized, photonic integration, Photonics, pluggable, power consumption, power consumption SFP, reach, Terabit

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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

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