Coherent Optical Systems

The environmental consequences of fossil fuels like coal, oil, and natural gas have triggered a crucial reassessment worldwide. The energy transition is a strategic pivot towards cleaner and more sustainable energy sources to reduce carbon emissions, and it requires a major collective effort from all industries.

In the information and communication technology (ICT) sector, the exponential increase in data traffic makes it difficult to keep emissions down and contribute to the energy transition. A 2020 study by Huawei estimates that the power consumption of the data center sector will increase threefold in the next ten years. Meanwhile, wireless access networks are expected to increase their power consumption even faster, more than quadrupling between 2020 and 2030.

These issues affect both the environment and the bottom lines of communications companies, which must commit increasingly larger percentages of their operating expenditure to cooling solutions.

As we explained in our previous articles , photonics and transceiver integration will play a key role in addressing these issues and making the ICT sector greener. EFFECT Photonics also believes that the transition of optical access networks to coherent 100G technology can help reduce power consumption.

This insight might sound counterintuitive at first since a coherent transceiver will normally consume more than twice the power of a direct detect one due to the use of a digital signal processor (DSP). However, by replacing the aggregation of multiple direct detect links with a single coherent link and skipping the upgrades to 56Gbps and going directly for 100Gbps, optical networks can save energy consumption, materials, and operational expenditures such as truck rolls.

The Impact of Streamlining Link Aggregation

The advanced stages of 5G deployment will require operators to cost-effectively scale fiber capacity in their fronthaul networks using more 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).

On the side of cable optical networks, the long-awaited migration to 10G Passive Optical Networks (10G PON) is happening and will also require the aggregation of multiple 10G links in optical line terminals (OLTs) and Converged Cable Access Platforms (CCAPs).

This type of link aggregation involves splitting larger traffic streams and can be intricate to integrate within an access ring. Furthermore, it carries an environmental impact.

A single 100G coherent pluggable consumes a maximum of six watts of power, which is significantly more than the two watts of power of a 10G SFP+ pluggable. However, aggregating four 10G links would require a total of eight SFP+ pluggables (two on each end) for a total maximum power consumption of 16 watts. Substituting this link aggregation for a single 100G coherent link would replace the eight SFP+ transceivers with just two coherent transceivers with a total power consumption of 12 watts. And on top of that reduced total power consumption, a single 100G coherent link more than doubles the capacity of aggregating those four 10G links.

Adopting a single 100G uplink also 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.

The Environmental Advantage of Leaping to 100G

While conventional wisdom may suggest a step-by-step progression from 28G midhaul and backhaul network links to 56G and then to 100G, it’s important to remember that each round of network upgrade carries an environmental impact.

Let’s look at an example. As per the European 5G observatory, a country like The Netherlands has deployed 12,858 5G base stations. There are several thousands of mid- and backhaul links connecting groups of these base stations to the 5G core networks. Every time these networks require an upgrade to accommodate increasing capacity, tens of thousands of pluggable transceivers must be replaced nationwide. This upgrade entails a substantial capital investment as well as resources and materials.

A direct leap from 28G mid- and backhaul links directly to coherent 100G allows network operators to have their networks already future-proofed for the next ten years. From an environmental perspective, it saves the economic and environmental impact of buying, manufacturing, and installing tens of thousands of 56G plugs across mobile network deployments. It’s a strategic choice that avoids the redundancy and excess resource utilization associated with two consecutive upgrades, allowing for a more streamlined and sustainable deployment.

Streamlining Operations with 100G ZR

Beyond the environmental considerations and capital expenditure, the operational issues and expenses of new upgrades cannot be overlooked. Each successive generation of upgrades necessitates many truck rolls and other operational expenditures, which can be both costly and resource-intensive.

Each truck roll involves a number of costs:

• Staff time (labor cost)
• Staff safety (especially in poor weather conditions)
• Staff opportunity cost (what complicated work could have been done instead of driving?)
• Fuel consumption (gasoline/petrol)
• Truck wear and tear

By directly upgrading from 25G to 100G, telecom operators can bypass an entire cycle of logistical and operational complexities, resulting in substantial savings in both time and resources.

This streamlined approach not only accelerates the transition toward higher speeds but also frees up resources that can be redirected toward other critical aspects of network optimization and sustainability initiatives.

Conclusion

In the midst of the energy transition, the ICT sector must also contribute toward a more sustainable and environmentally responsible future. While it might initially seem counterintuitive, upgrading to 100G coherent pluggables can help streamline optical access network architectures, reducing the number of pluggables required and their associated power consumption. Furthermore, upgrading these access network mid- and backhaul links directly to 100G leads to future-proofed networks that will not require financially and environmentally costly upgrades for the next decade.

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: 4G vs. 5G, 5G Networks, Base Stations, Coherent Optical Systems, Data center architecture, data centers, Decentralization, Electrical Power, Electronic Equipment, Energy Transition, heat dissipation, miniaturization, Optical Fiber, Optical System-On-Chip (SoC), Photonics, Pluggable Transceivers, Power Usage Effectiveness (PUE), Semiconductor Industry, Wafer Scale Processes, Wireless Transmission

The world relies heavily on traditional fossil fuels like coal, oil, and natural gas, but their environmental impact has prompted a critical reevaluation. The energy transition is a strategic pivot towards cleaner and more sustainable energy sources to reduce carbon emissions.

In the information and communication technology (ICT) sector, the exponential increase in data traffic makes it difficult to keep emissions down and contribute to the energy transition. A 2020 study by Huawei estimates that the power consumption of the data center sector will increase threefold in the next ten years. Meanwhile, wireless access networks are expected to increase their power consumption even faster, more than quadrupling between 2020 and 2030.

These issues affect both the environment and the bottom lines of communications companies, which must commit increasingly larger percentages of their operating expenditure to cooling solutions.

As we explained in our previous article, photonics will play a key role in addressing these issues and making the ICT sector greener. However, contributing to a successful energy transition requires more than replacing specific electronic components with photonic ones. Existing photonic components, such as optical transceivers, must also be upgraded to more highly integrated and power-efficient ones. As we will show in this article, even small improvements in existing optical transceivers can snowball into more significant power savings and carbon emissions reduction.

How One Watt of Savings Scales Up

Let’s discuss an example to show how a seemingly small improvement of one watt in pluggable transceiver power consumption can quickly scale up into major energy savings.

A 2020 paper from Microsoft Research estimates that for a metropolitan region of 10 data centers with 16 fiber pairs each and 100-GHz DWDM per fiber, the regional interconnect network needs to host 12,800 transceivers.

This number of transceivers could increase by a third in the coming years since the 400ZR transceiver ecosystem supports a denser 75 GHz DWDM grid, so this number of transceivers would increase to 17,000. Therefore, saving a watt of power in each transceiver would lead to a total of 17 kW in savings.

The power savings don’t end there, however. The transceiver is powered by the server, which is then powered by its power supply and, ultimately, the national electricity grid. On average, 2.5 Watts must be supplied from the national grid for every watt of power the transceiver uses. When applying that 2.5 factor, the 17 kW in savings we discussed earlier are, in reality, 42.5 kW.

In a year of power consumption,  this rate adds up to a total of 372 MWh in power consumption savings. According to the US Environmental Protection Agency (EPA), these power savings in a single metro data center network are equivalent to 264 metric tons of carbon dioxide emissions. These emissions are equivalent to consuming 610 barrels of oil and could power up to 33 American homes for a year.

Saving Power through Integration

Having explained the potential impact of transceiver power savings, let’s delve into how to save this power.

Before 2020, Apple made its computer processors with discrete components. In other words, electronic components were manufactured on separate chips, and then these chips were assembled into a single package. However, the interconnections between the chips produced losses and incompatibilities that made their devices less energy efficient. After 2020, starting with Apple’s M1 processor, they fully integrated all components on a single chip, avoiding losses and incompatibilities. As shown in the table below, this electronic system-on-chip (SoC) consumes a third of the power compared to the processors with discrete components used in their previous generations of computers.

𝗠𝗮𝗰 𝗠𝗶𝗻𝗶 𝗠𝗼𝗱𝗲𝗹	𝗣𝗼𝘄𝗲𝗿 𝗖𝗼𝗻𝘀𝘂𝗺𝗽𝘁𝗶𝗼𝗻
	𝗜𝗱𝗹𝗲	𝗠𝗮𝘅
2023, M2	7	5
2020, M1	7	39
2018, Core i7	20	122
2014, Core i5	6	85
2010, Core 2 Duo	10	85
2006, Core Solo or Duo	23	110
2005, PowerPC G4	32	85
Table 1: Comparing the power consumption of a Mac Mini with an M1 and M2 SoC chips to previous generations of Mac Minis. [Source: Apple’s website]

The photonics industry would benefit from a similar goal: implementing a photonic system-on-chip. Integrating all the required optical functions on a single chip can minimize the losses and make devices such as optical transceivers more efficient.

For example, the monolithic integration of all tunable laser functions allows EFFECT Photonics to develop a novel pico-ITLA (pITLA) module that will become the world’s smallest ITLA for coherent optical transceivers. 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. This increased integration aims to reduce the power and cost per bit transmitted further.

Early Testing Avoids Wastage

Testing is another aspect of the manufacturing process that impacts sustainability. The earlier faults are found in the testing process, the greater the impact on the materials and energy to process defective chips. Ideally, testing should happen not only on the final, packaged transceiver but also in the earlier stages of PIC fabrication, such as measuring after wafer processing or cutting the wafer into smaller dies.

When optical testing is done just on the finalized transceiver package, the whole package must often be discarded, even if just one component does not pass the testing process. This action can lead to a massive waste of materials that cannot be ”fixed” or reused at this stage of the manufacturing process.

Full integration of optical devices enables earlier optical testing on the semiconductor wafer and dies. By testing the dies and wafers directly before packaging, manufacturers need only discard the bad dies rather than the whole package, which saves valuable energy and materials.

Takeaways

For photonics to enable an energy transition in the ICT sector, it must be as accessible and easy to use as electronics. Like electronics, it must be built on a wafer-scale process that can produce millions of chips monthly.

Increased integration of photonic devices such as optical transceivers does not just reduce their energy consumption; it also makes them easier to produce at high volumes. Integrating all functions of an optical device into a single chip makes it much easier to scale up the manufacturing of that device. This scaling will drive down production costs, making integrated photonics more widely available and paving the way for its impactful integration into numerous technologies across the globe.

Tags: 4G vs. 5G, 5G Networks, Base Stations, Coherent Optical Systems, Data center architecture, data centers, Decentralization, Electrical Power, Electronic Equipment, Energy Transition, heat dissipation, miniaturization, Optical Fiber, Optical System-On-Chip (SoC), Photonics, Pluggable Transceivers, Power Usage Effectiveness (PUE), Semiconductor Industry, Wafer Scale Processes, Wireless Transmission

The world relies heavily on traditional fossil fuels like coal, oil, and natural gas, but their environmental impact has prompted a critical reevaluation. The energy transition is a strategic pivot towards cleaner and more sustainable energy sources to reduce carbon emissions.

The energy transition has gained momentum over the last decade, with many countries setting ambitious targets for carbon neutrality and renewable energy adoption. Governments, industries, and communities worldwide are investing heavily in renewable infrastructure and implementing policies to reduce emissions.

In the information and communication technology (ICT) sector, the exponential increase in data traffic makes it difficult to keep emissions down and contribute to the energy transition. Data centers and 5G networks might be hot commodities, but the infrastructure that enables them runs even hotter. Electronic equipment generates plenty of heat; the more heat energy an electronic device dissipates, the more money and energy must be spent to cool it down.

A 2020 study by Huawei estimates that the power consumption of the data center sector will increase threefold in the next ten years. Meanwhile, wireless access networks are expected to increase their power consumption even faster, more than quadrupling between 2020 and 2030.

These issues affect the environment as well as the bottom lines of communications companies, which must commit increasingly larger percentages of their operating expenditure to cooling solutions.

Decreasing energy consumption and costs in the ICT sector requires more efficient equipment, and photonics technology will be vital in enabling such a goal. Photonics can transmit information more efficiently than electronics and ensure that the exponential increase in data traffic does not become an exponential increase in power consumption.

Photonics’ Power Advantages

Photonics and light have a few properties that improve the energy efficiency of data transmission compared to electronics and electric signals.

When electricity moves through a wire or coaxial cable, it encounters resistance, which leads to energy loss in the form of heat. Conversely, light experiences much less resistance when traveling through optical fiber, resulting in significantly lower energy loss during data transmission. As shown in the figure below, this energy loss gets exponentially worse with faster (i.e., higher-frequency) signals that can carry more data. Photonics scales much better with increasing frequency and data.

These losses and heat generation in electronic data transmission lead to higher power consumption, more cooling systems use, and reduced transmission distances compared to photonic transmission.

The low-loss properties of optical fibers enable light to be transmitted over vastly longer distances than electrical signals. Due to their longer reach, optical signals also save more power than electrical signals by reducing the number of times the signal needs regeneration.

With all these advantages, photonics entails a lower power per bit transmitted compared to electronic transmission, which often translates to a lower cost per bit.

Photonics’ Capacity Advantages

Aside from being more power efficient than electronics, another factor that decreases the power and cost per bit of photonic transmission is its data capacity and bandwidth.

Light waves have much higher frequencies than electrical signals. This means they oscillate more rapidly, allowing for a higher information-carrying capacity. In other words, light waves can encode more information than electrical signals.

Optical fibers have a much wider bandwidth than electrical wires or coaxial cables. This means they can carry a broader range of signals, allowing for higher data rates and more transmission of parallel data streams. Thanks to technologies such as dense wavelength division multiplexing (DWDM), multiple data channels can be sent and received simultaneously, significantly increasing the transmission capacity of an optical fiber.

Overall, the properties of light make it a superior medium for transmitting large volumes of data over long distances compared to electricity.

Transfer Data, Not Power

Photonics can also play a key role in rethinking the architecture of data centers. Photonics enables a more decentralized system of data centers with branches in different geographical areas connected through high-speed optical fiber links to cope with the strain of data center clusters on power grids.

For example, data centers can relocate to areas with available spare power, preferably from nearby renewable energy sources. Efficiency can increase further by sending data to branches with spare capacity. The Dutch government has already proposed this kind of decentralization as part of its spatial strategy for data centers.

Takeaways

Despite all these advantages, electronics’s one significant advantage over photonics is accessibility.

Electronic components can be easily manufactured at scale, ordered online from a catalog, soldered into a board, and integrated into a product. For photonics to enable an energy transition in the ICT sector, it must be as accessible and easy to use as electronics.

However, for photonics to truly scale and become as accessible as electronics, more investment is necessary to scale production and adapt existing electronics processes to photonics. This scaling will drive down production costs, making integrated photonics more widely available and paving the way for its impactful integration into numerous technologies across the globe.

Tags: 4G vs. 5G, 5G Networks, Base Stations, Coherent Optical Systems, Data center architecture, data centers, Decentralization, Electrical Power, Electronic Equipment, Energy Transition, heat dissipation, miniaturization, Optical Fiber, Optical System-On-Chip (SoC), Photonics, Pluggable Transceivers, Power Usage Effectiveness (PUE), Semiconductor Industry, Wafer Scale Processes, Wireless Transmission