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Insights

October 12, 2022

What’s Inside a Tunable Laser for Coherent Systems?

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 the 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 enabled the widespread implementation of IP over DWDM solutions. Self-tuning algorithms have also made DWDM solutions more widespread by simplifying installation and maintenance. Hence, many application cases—metro transport, data center interconnects, and —are moving towards tunable pluggables.

The tunable laser is a core component of all these tunable communication systems, both direct detection and coherent. The laser generates the optical signal modulated and sent over the optical fiber. Thus, the purity and strength of this signal will have a massive impact on the bandwidth and reach of the communication system. This article will clarify some critical aspects of laser design for communication systems.

External and Integrated Lasers: What’s the Difference?

The promise of silicon photonics (SiP) is compatibility with existing electronic manufacturing ecosystems and infrastructure. Integrating silicon components on a single chip with electronics manufacturing processes can dramatically reduce the footprint and the cost of optical systems and open avenues for closer integration with silicon electronics on the same chip. However, the one thing silicon photonics misses is the laser component.

Silicon is not a material that can naturally emit laser light from electrical signals. Decades of research have created silicon-based lasers with more unconventional nonlinear optical techniques. Still, they cannot match the power, efficiency, tunability, and cost-at-scale of lasers made from indium phosphide (InP) and III-V compound semiconductors.

Therefore, making a suitable laser for silicon photonics does not mean making an on-chip laser from silicon but an external laser from III-V materials such as InP. This light source will be coupled via optical fiber to the silicon components on the chip while maintaining a low enough footprint and cost for high-volume integration. The external laser typically comes in the form of an integrable tunable laser assembly (ITLA).

In contrast, the InP platform can naturally emit light and provide high-quality light sources and amplifiers. This allows for photonic system-on-chip designs that include an integrated laser on the chip. The integrated laser carries the advantage of reduced footprint and power consumption compared to an external laser. These advantages become even more helpful for PICs that need multiple laser channels.

Finally, integrated lasers enable earlier optical testing on the semiconductor wafer and die. By testing the dies and wafers directly before packaging them into a transceiver, manufacturers need only discard the bad dies rather than the whole package, which saves valuable energy, materials, and cost.

Figure 1: Package vs. die level testing. Manufacturers can find faults earlier by testing at the die level, which avoids wasting packaging materials.

Using an external or integrated laser depends on the transceiver developer’s device requirements, supply chain, and manufacturing facilities and processes. At EFFECT Photonics, we have the facilities and expertise to provide fully-integrated InP optical systems with an integrated laser and the external laser component that a silicon photonics developer might need for their optical system.

What are the key requirements for a laser in coherent systems?

In his recent talk at ECOC 2022, our Director of Product Management, Joost Verberk, outlined five critical parameters for laser performance.

Tunability: With telecom providers needing to scale up their network capacity without adding more fiber infrastructure, combining tunable lasers with dense wavelength division multiplexing (DWDM) technology becomes necessary. These tunable optical systems have become more widespread thanks to self-tuning technology that removes the need for manual tuning. This makes their deployment and maintenance easier.
Spectral Purity: Coherent systems encode information in the phase of the light, and the purer the light source is, the more information it can transmit. An ideal, perfectly pure light source can generate a single, exact color of light. However, real-life lasers are not pure and will generate light outside their intended color. The size of this deviation is what we call the laser linewidth. An impure laser with a large linewidth will have a more unstable phase that propagates errors in its transmitted data, as shown in the diagram below. This means it will transmit at a lower speed than desired.

Figure 2: Impact of laser linewidth on phase noise during coherent transmission. The diagram shows the points transmitted by a coherent system at different laser linewidths (measured by frequency). The larger the laser linewidth, the blurrier the transmitted points become, to the point that they cannot be distinguished from each other—source: Ragheb et al. (2017).

Dimensions: As the industry moves towards packing more and more transceivers on a single router faceplate, tunable lasers need to maintain performance and power while moving to smaller footprints. Laser manufacturers have achieved size reductions thanks to improved integration without impacting laser purity and power, moving from ITLA to micro-ITLA and nano-ITLA form factors in a decade.
Environmental Resistance: Lasers used in edge and access networks will be subject to harsh environments, like temperature and moisture changes. For these use cases, lasers should operate in the industrial temperature (I-temp) range of -40 to 85ºC for these environments.
Transmit Power: The required laser output power will depend on the application and the system architecture. For example, a laser fully integrated into the chip can reach higher transmit powers more easily because it avoids the interconnection losses of an external laser. Still, shorter-reach applications might not necessarily need such powers.

Figure 3: Comparing transmit power, noise, size, and cost of line card transponders and different transceiver pluggable modules. Fully integrated QSFP-DD modules include lasers, amplifiers, and filters inside a single PIC to deliver high transmit powers at a small size and low cost.

The Promise of Multi-Laser Arrays

Earlier this year, Intel Labs demonstrated an eight-wavelength laser array fully integrated on a silicon wafer. These milestones are essential for tunable DWDM because the laser arrays can allow for multi-channel transceivers that are more cost-effective when scaling up to higher speeds.

Let’s say we need a link with 1.6 Terabits/s of capacity. There are three ways we could implement it:

Four modules of 400G: This solution uses existing off-the-shelf modules but has the largest footprint. It requires four slots in the router faceplate and an external multiplexer to merge these into a single 1.6T channel.
One module of 1.6T: This solution will not require the external multiplexer and occupies just one plug slot on the router faceplate. However, making a single-channel 1.6T device has the highest complexity and cost.
One module with four internal channels of 400G: A module with an array of four lasers (and thus four different 400G channels) will only require one plug slot on the faceplate while avoiding the complexity and cost of the single-channel 1.6T approach.

Table 1: Comparison of different ways to implement a 1.6 Terabit/s link: four modules of 400G, a single-channel 1.6T module, and a module with four channels of 400G.

Multi-laser array and multi-channel solutions will become increasingly necessary to increase link capacity in coherent systems. They will not need more slots in the router faceplate while simultaneously avoiding the higher cost and complexity of increasing the speed with just a single channel.

Takeaways

The combination of tunable lasers and dense wavelength division multiplexing (DWDM) allows the datacom and telecom industries to expand their network capacity without increasing their existing fiber infrastructure. Thanks to the miniaturization of coherent technology and self-tuning algorithms, many application cases—metro transport, data center interconnects, and future access networks—will eventually move towards coherent tunable pluggables.

These new application cases will have to balance the laser parameters we described early—tunability, purity, size, environmental resistance, power—depending on their material platforms, system architecture, and requirements. Some will need external lasers; some will want a fully-integrated laser. Some will need multi-laser arrays to increase capacity; others need more stringent temperature certifications.

Following these trends, at EFFECT Photonics, we are not only developing the capabilities to provide a complete, coherent transceiver solution but also the external nano-ITLA units needed by other vendors.

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Tags: coherent, DBR, DFB, ECL, full integration, InP, ITLA, micro ITLA, nano ITLA, SiP, tunable

Insights

October 5, 2022

The Growing Photonics Cluster of the Boston Area

As they lighted the candles in their ship, the Pilgrim families traveling on the Mayflower had no…

As they lighted the candles in their ship, the Pilgrim families traveling on the Mayflower had no idea they would help build a nation that would become a major pioneer in light technology and many other fields.

The United States features many areas with a strong photonics background, including the many companies in California’s Silicon Valley and the regions close to the country’s leading optics universities, such as Colorado, New York, Arizona, and Florida.

However, the Greater Boston area and Massachusetts state, in general, are becoming an increasingly important photonics hub with world-class universities and many successful optics and photonics initiatives and companies. Let’s talk a bit more about their legacy with light-based technology and the history of the town of Maynard with the high-tech industry.

From World-Class Labs to the Real World

The Boston area features many world-class universities collaborating with the government and industry to develop new photonics technology. Harvard, the Massachusetts Institute of Technology (MIT), Boston University, Tufts University, and Northeastern University are major research institutions in the area that lead many photonics-related initiatives.

The state of Massachusetts, in general, has also been home to several prosperous photonics businesses, and initiatives are being made to capitalize on Boston’s extensive medical industry knowledge to boost biomedical optics and photonics. Raytheon, Polaroid, and IPG Photonics are examples of Massachusetts-based businesses that promoted optical technology.

The US federal government and Massachusetts state are committing resources to get these academic and industry partners to collaborate as much as possible. In 2015, the Lab for Education and Application Prototypes (LEAP) network was established as part of a federal drive to revive American manufacturing. The Massachusetts Manufacturing Innovation Initiative, a state grant program, and AIM Photonics, the national manufacturing institution, each contributed $11.3 million to constructing labs around Massachusetts universities and colleges.

The LEAP Network objectives are to teach integrated photonics manufacturing practice, offer companies technician training and certification, encourage company engagement in the tool, process, and application upgrades, and support AIM Photonics in their manufacturing and testing.

These partnerships form a statewide ecosystem to educate the manufacturing workforce throughout the photonics supply chain. The facilities’ strategic placement next to both universities and community colleges allows them to attract students from all areas and stages of their careers, from technicians to engineers to fundamental researchers.

From the Mill to High Tech: The Story of Maynard

A trip down Route 2 into Middlesex County, 25 miles northwest of Boston, will take one past apple orchards, vineyards, and some of Massachusetts’ most stunning nature preserves before arriving at a historic mill on the Assabet River. The community around this mill, Maynard, is a charming and surprisingly historical hub of economic innovation that houses an emerging tech ecosystem.

location-maynard-clocktower — Historic Assabet Woolen Mill, built in 1847, on Main Street on Assabet River in Maynard’s historic town center in spring, Maynard, Massachusetts, USA.

The renowned Assabet Woolen Mill was established for textile manufacturing in 1847 by Amory Maynard, who by the age of 16 was managing his own sawmill company. Initially a carpet manufacturing plant, Maynard’s enterprise produced blankets and uniforms for the Union Army during the Civil War. The company employed immigrants from Ireland, Finland, Poland, Russia, and Italy, many of them coming to the mill for jobs as soon as they arrived in the nation. By the 1930s, the town of Maynard was recognized as one of the most multi-ethnic places in the state.

The Assabet Woolen Mill continued to create textiles until 1950. The 11-acre former mill complex, currently named Mill and Main, is the contemporary expression of the town’s evolution and relationship with innovative industry.

The Digital Equipment Corporation (DEC) occupied the facility before the end of the 50s with just $70,000 cash and three engineers. From the 1960s onward, DEC became a major global supplier of computer systems and enjoyed tremendous growth. It’s hard to overstate the company’s impact on Maynard, which became the ” Mini Computer Capital of the World” in barely twenty years.

Following DEC’s departure, the mill complex was sold and rented out to a fresh group of young and ambitious computer startups, many of whom are still operating today. Since then, more people and companies have joined, noting the affordable real estate, the enjoyable commute and environs, and the obvious cluster of IT enterprises. For example, when Acacia Communications, Inc. was established in 2009 and needed a home, Maynard’s mill space was a natural fit.

Similarly, EFFECT Photonics is proud to make a home in Maynard´s historic mill space and be a part of this community’s innovative heritage. We hope our work can serve as a positive example and inspiration for the neighborhood and help more innovators and inventors come to Maynard.

Tags: Boston, Boston University, DEC, Maynard, MIT, Photonics, Woolen Mill

We interview Russell Fuerst, our VP of Digital Signal Processing.

Insights

September 29, 2022

The Future of Coherent DSP Design: Interview with Russell Fuerst

Digital signal processors (DSPs) are the heart of coherent communication systems. They not only encode/decode…

Digital signal processors (DSPs) are the heart of coherent communication systems. They not only encode/decode data into the three properties of a light signal (amplitude, phase, polarization) but also handle error correction, analog-digital conversation, Ethernet framing, and compensation of dispersion and nonlinear distortion. And with every passing generation, they are assigned more advanced functions such as probabilistic constellation shaping.

There are still many challenges ahead to improve DSPs and make them transmit even more bits in more energy-efficient ways. Now that EFFECT Photonics has incorporated talent and intellectual property from Viasat’s Coherent DSP team, we hope to contribute to this ongoing research and development and make transceivers faster and more sustainable than ever. We ask Russell Fuerst, our Vice-President of Digital Signal Processing, how we can achieve these goals.

What’s the most exciting thing about joining EFFECT Photonics?

Before being acquired by EFFECT Photonics, our DSP design team has been a design-for-hire house. We’ve been doing designs for other companies that have put those designs in their products. By joining EFFECT Photonics, we can now do a design and stamp our brand on it. That’s exciting.

The other exciting thing is to have all the technologies under one roof. Having everything from the DSP to the PIC to the packaging and module-level elements in one company will allow us to make our products that much better.

We also find the company culture to be very relaxed and very collaborative. Even though we’re geographically diverse, it’s been straightforward to understand what other people and groups in the company are doing. It’s easy to talk to others and find out whom you need to talk to. There’s not a whole lot of organizational structure that blocks communication, so it’s been excellent from that perspective.

People at EFFECT Photonics were welcoming from day one, making us that much more excited to join.

What key technology challenges must be solved by DSP designers to thrive in the next 5 to 10 years?

The key is to bring the power down while also increasing the performance.

In the markets where coherent has been the de-facto solution, I think it’s essential to understand how to drive cost and power down either through the DSP design itself or by integrating the DSP with other technologies within the module. That will be where the benefits come from in those markets.

Similarly, there are markets where direct detection is the current technology of choice. We must understand how to insert coherent technology into those markets while meeting the stringent requirements of those important high-volume markets. Again, this progress will be largely tied to performance within the power and cost requirements.

As DSP technology has matured, other aspects outside of performance are becoming key, and understanding how we can work that into our products will be the key to success.

How do you think the DSP can be more tightly integrated with the PIC?

This is an answer that will evolve over time. We will become more closely integrated with the team in Eindhoven and learn some of the nuances of their mature design process. And similarly, they’ll understand the nuances of our design process that have matured over the years. As we understand the PIC technology and our in-house capabilities better, that will bring additional improvements that are currently unknown.

Right now, we are primarily focused on the obvious improvements tied to the fully-integrated platform. For example, the fact that we can have the laser on the PIC because of the active InP material. We want to understand how we co-design aspects of the module and shift the complexity from one design piece or component to another, thanks to being vertically integrated.

Another closely-tied area for improvement is on the modulator side. We think that the substantially lower drive voltages required for the InP modulator give us the possibility to eliminate some components, such as RF drivers. We could potentially drive the modulator directly from that DSP without any intermediary electronics, which would reduce the cost and power consumption. That’s not only tied to the lower drive voltages but also some proprietary signal conditioning we can do to minimize some of the nonlinearities in the modulator and improve the performance.

What are the challenges and opportunities of designing DSPs for Indium phosphide instead of silicon?

So, we already mentioned two opportunities with the laser and the modulator.

I think the InP integration makes the design challenges smaller than those facing DSP design for silicon photonics. The fact is that InP can have more active integrated components and that DSPs are inherently active electronic devices, so getting the active functions tuned and matched over time will be a challenge. It motivates our EFFECT DSP team to quickly integrate with the experienced EFFECT PIC design team to understand the fundamental InP platform a bit better. Once we understand it, the DSP designs will get more manageable with improved performance, especially as we have control over the designs of both DSP and PIC. As we get to the point where co-packaging is realized, there will also be some thermal management issues to consider.

When we started doing coherent DSP designs for optical communication over a decade ago, we pulled many solutions from the RF wireless and satellite communications space into our initial designs. Still, we couldn’t bring all those solutions to the optical markets.

However, when you get more of the InP active components involved, some of those solutions can finally be brought over and utilized. They were not used before in our designs for silicon photonics because silicon is not an active medium and lacked the performance to exploit these advanced techniques.

For example, we have done proprietary waveforms tuned to specific satellite systems in the wireless space. Our DSP team was able to design non-standard constellations and modulation schemes that increased the capacity of the satellite link over the previous generation of satellites. Similarly, we could tune the DSP’s waveform and performance to the inherent advantages of the InP platform to improve cost, performance, bandwidth utilization, and efficiency. That’s something that we’re excited about.

Takeaways

As Russell explained, the big challenge for DSP designers continues to be increasing performance while keeping down the power consumption. Finding ways to integrate the DSP more deeply with the InP platform can overcome this challenge, such as direct control of the laser and modulator from the DSP to novel waveform shaping methods. The presence of active components in the InP platforms also gives DSP designers the opportunity to import more solutions from the RF wireless space.

We look forward to our new DSP team at EFFECT Photonics settling into the company and trying out all these solutions to make DSPs faster and more sustainable!

Tags: coherent, DSP, energy efficient, InP, integration, performance, power consumption, Sustainable, Viasat

Insights

September 15, 2022

The Future of Passive Optical Networks

Like every other telecom network, cable networks had to change to meet the growing demand…

Like every other telecom network, cable networks had to change to meet the growing demand for data. These demands led to the development of hybrid fiber-coaxial (HFC) networks in the 1990s and 2000s. In these networks, optical fibers travel from the cable company hub and terminate in optical nodes, while coaxial cable connects the last few hundred meters from the optical node to nearby houses. Most of these connections were asymmetrical, giving customers more capacity to download data than upload.

That being said, the way we use the Internet has evolved over the last ten years. Users now require more upstream bandwidth thanks to the growth of social media, online gaming, video calls, and independent content creation such as video blogging. The DOCSIS standards that govern data transmission over coaxial cables have advanced quickly because of these additional needs. For instance, full-duplex transmission with symmetrical upstream and downstream channels is permitted under the most current DOCSIS 4.0 specifications.

Fiber-to-the-home (FTTH) systems, which bring fiber right to the customer’s door, are also proliferating and enabling Gigabit connections quicker than HFC networks. Overall, extending optical fiber deeper into communities (see Figure 1 for a graphic example) is a critical economic driver, increasing connectivity for the rural and underserved. These investments also lead to more robust competition among cable companies and a denser, higher-performance wireless network.

*Figure 1. Comparison between legacy fiber deployments in access networks vs. future deep fiber deployments.*

Passive optical networks (PONs) are a vital technology to cost-effectively expand the use of optical fiber within access networks and make FTTH systems more viable. By creating networks using passive optical splitters, PONs avoid the power consumption and cost of active components in optical networks such as electronics and amplifiers. PONs can be deployed in mobile fronthaul and mid-haul for macro sites, metro networks, and enterprise scenarios.

Despite some success from PONs, the cost of laying more fiber and the optical modems for the end users continue to deter carriers from using FTTH more broadly across their networks. This cost problem will only grow as the industry moves into higher bandwidths, such as 50G and 100G, requiring coherent technology in the modems.

Therefore, new technology and manufacturing methods are required to make PON technology more affordable and accessible. For example, wavelength division multiplexing (WDM)-PON allows providers to make the most of their existing fiber infrastructure. Meanwhile, simplified designs for coherent digital signal processors (DSPs) manufactured at large volumes can help lower the cost of coherent PON technology for access networks.

The Advantages of WDM PONs

Previous PON solutions, such as Gigabit PON (GPON) and Ethernet PON (EPON), used time-division multiplexing (TDM) solutions. In these cases, the fiber was shared sequentially by multiple channels. These technologies were initially meant for the residential services market, but they scale poorly for the higher capacity of business or carrier services. PON standardization for 25G and 50G capacities is ready but sharing a limited bitrate among multiple users with TDM technology is an insufficient approach for future-proof access networks.

This WDM-PON uses WDM multiplexing/demultiplexing technology to ensure that data signals can be divided into individual outgoing signals connected to buildings or homes. This hardware-based traffic separation gives customers the benefits of a secure and scalable point-to-point wavelength link. Since many wavelength channels are inside a single fiber, the carrier can retain very low fiber counts, yielding lower operating costs.

Figure 2: Example of a simplified WDM-PON architecture with 64 different wavelengths. It includes multiplexers (MUX) and demultiplexers (DEMUX) as well as a splitter device based on arrayed waveguide gratings (AWGs). This splitter is found between the optical line terminal (OLT) at the company headend and the optical network unit (ONU) at the customer’s end. Figure sourced from *this paper* *from Sharma et al.*

WDM-PON has the potential to become the unified access and backhaul technology of the future, carrying data from residential, business, and carrier wholesale services on a single platform. We discussed this converged access solution in one of our previous articles. Its long-reach capability and bandwidth scalability enable carriers to serve more customers from fewer active sites without compromising security and availability.

Migration to the WDM-PON access network does require a carrier to reassess how it views its network topology. It is not only a move away from operating parallel purpose-built platforms for different user groups to one converged access and backhaul infrastructure. It is also a change from today’s power-hungry and labor-intensive switch and router systems to a simplified, energy-efficient, and transport-centric environment with more passive optical components.

The Possibility of Coherent Access

As data demands continue to grow, direct detect optical technology used in prior PON standards will not be enough. The roadmap for this update remains a bit blurry, with different carriers taking different paths. For example, future expansions might require using 25G or 50G transceivers in the cable network, but the required number of channels in the fiber might not be enough for the conventional optical band (the C-band). Such a capacity expansion would therefore require using other bands (such as the O-band), which comes with additional challenges. An expansion to other optical bands would require changes in other optical networking equipment, such as multiplexers and filters, which increases the cost of the upgrade.

An alternative solution could be upgrading instead to coherent 100G technology. An upgrade to 100G could provide the necessary capacity in cable networks while remaining in the C-band and avoiding using other optical bands. This path has also been facilitated by the decreasing costs of coherent transceivers, which are becoming more integrated, sustainable, and affordable. You can read more about this subject in one of our previous articles.

For example, the renowned non-profit R&D center CableLabs announced a project to develop a symmetric 100G Coherent PON (C-PON). According to CableLabs, the scenarios for a C-PON are many: aggregation of 10G PON and DOCSIS 4.0 links, transport for macro-cell sites in some 5G network configurations, fiber-to-the-building (FTTB), long-reach rural scenarios, and high-density urban networks.

CableLabs anticipates C-PON and its 100G capabilities to play a significant role in the future of access networks, starting with data aggregation on networks that implement a distributed access architecture (DAA) like Remote PH. You can learn more about these networks here.

Combining Affordable Designs with Affordable Manufacturing

The main challenge of C-PON is the higher cost of coherent modulation and detection. Coherent technology requires more complex and expensive optics and digital signal processors (DSPs). Plenty of research is happening on simplifying these coherent designs for access networks. However, a first step towards making these optics more accessible is the 100ZR standard.

100ZR is currently a term for a short-reach (~80 km) coherent 100Gbps transceiver in a QSFP pluggable size. Targeted at the metro edge and enterprise applications that do not require 400ZR solutions, 100ZR provides a lower-cost, lower-power pluggable that also benefits from compatibility with the large installed base of 50 GHz and legacy 100 GHz multiplexer systems.

Another way to reduce the cost of PON technology is through the economics of scale, manufacturing pluggable transceiver devices at a high volume to drive down the cost per device. And with greater photonic integration, even more, devices can be produced on a single wafer. This economy-of-scale principle is the same behind electronics manufacturing, which must be applied to photonics.

Researchers at the Technical University of Eindhoven and the JePPIX consortium have modeled how this economy of scale principle would apply to photonics. If 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 tens of Euros. This must be the goal of the optical transceiver industry.

Figure 3: Modelling of photonic integrated chip (PIC) cost as a function of the aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost. Model and graph provided by Prof. Meint Smit, TU Eindhoven.

Takeaways

Integrated photonics and volume manufacturing will be vital for developing future passive optical networks. PONs will use more WDM-PON solutions for increased capacity, secure channels, and easier management through self-tuning algorithms.

Meanwhile, PONs are also moving into incorporating coherent technology. These coherent transceivers have been traditionally too expensive for end-user modems. Fortunately, more affordable coherent transceiver designs and standards manufactured at larger volumes can change this situation and decrease the cost per device.

Tags: 100G, 5G, 6G, access, access networks, aggregation, backhaul, capacity, coherent, DWDM, fronthaul, Integrated Photonics, LightCounting, live events, metro, midhaul, mobile, mobile access, mobile networks, network, optical networking, optical technology, photonic integrated chip, photonic integration, Photonics, PIC, PON, programmable photonic system-on-chip, solutions, technology, VR, WDM

Insights

September 7, 2022

How Many DWDM Channels Do You Really Need?

Optical fiber and dense wavelength division multiplex (DWDM) technology are moving towards the edges of…

Optical fiber and dense wavelength division multiplex (DWDM) technology are moving towards the edges of networks. In the case of new 5G networks, operators will need more fiber capacity to interconnect the increased density of cell sites, often requiring replacing legacy time-division multiplexing transmission with higher-capacity DWDM links. In the case of cable and other fixed access networks, new distributed access architectures like Remote PHY free up ports in cable operator headends to serve more bandwidth to more customers.

A report by Deloitte summarizes the reasons to expand the reach and capacity of optical access networks: “Extending fiber deeper into communities is a critical economic driver, promoting competition, increasing connectivity for the rural and underserved, and supporting densification for wireless.”

*Figure 1: Comparison between legacy and future deep fiber deployments in access networks. Yellow lines represent copper links, blue represents coaxial, and the green represents optical fiber.*

To achieve such a deep fiber deployment, operators look to DWDM solutions to expand their fiber capacity without the expensive laying of new fiber. DWDM technology has become more affordable than ever due to the availability of low-cost filters and SFP transceiver modules with greater photonic integration and manufacturing volumes. Furthermore, self-tuning technology has made the installation and maintenance of transceivers easier and more affordable.

Despite the advantages of DWDM solutions, their price still causes operators to second-guess whether the upgrade is worth it. For example, mobile fronthaul applications don’t require all 40, 80, or 100 channels of many existing tunable modules. Fortunately, operators can now choose between narrow- or full-band tunable solutions that offer a greater variety of wavelength channels to fit different budgets and network requirements.

Example: Fullband Tunables in Cable Networks

Let’s look at what happens when a fixed access network needs to migrate to a distributed access architecture like Remote PHY.

A provider has a legacy access network with eight optical nodes, and each node services 500 customers. To give higher bandwidth capacity to these 500 customers, the provider wants to split each node into ten new nodes for fifty customers. Thus, the provider goes from having eight to eighty nodes. Each node requires the provider to assign a new DWDM channel, occupying more and more of the optical C-band. This network upgrade is an example that requires a fullband tunable module with coverage across the entire C-band to provide many DWDM channels with narrow (50 GHz) grid spacing.

Furthermore, using a fullband tunable module means that a single part number can handle all the necessary wavelengths for the network. In the past, network operators used fixed wavelength DWDM modules that must go into specific ports. For example, an SFP+ module with a C16 wavelength could only work with the C16 wavelength port of a DWDM multiplexer. However, tunable SFP+ modules can connect to any port of a DWDM multiplexer. This advantage means technicians no longer have to navigate a confusing sea of fixed modules with specific wavelengths; a single tunable module and part number will do the job.

Figure 2: Example of a point-to (multi-)point system with fullband tunable modules. Each of the 10G SFP+ modules is a full C-band tunable covering ITU channels 14 to 61. This link uses the different wavelengths for up-and downstream transmission, allowing for a full-duplex transmission across a single fiber and multiplexer.

Overall, fullband tunable modules will fit applications that need a large number of wavelength channels to maximize the capacity of fiber infrastructure. Metro transport or data center interconnects (DCIs) are good examples of applications with such requirements.

Example: Narrowband Tunables in Mobile Fronthaul

The transition to 5G and beyond will require a significant restructuring of mobile network architecture. 5G networks will use higher frequency bands, which require more cell sites and antennas to cover the same geographical areas as 4G. Existing antennas must upgrade to denser antenna arrays. These requirements will put more pressure on the existing fiber infrastructure, and mobile network operators are expected to deliver their 5G promises with relatively little expansion in their fiber infrastructure.

*Figure 3: Simplified diagram that shows and compares the building blocks of 4G (left) and 5G (right) access networks and the links between these blocks.*

DWDM solutions will be vital for mobile network operators to scale capacity without laying new fiber. However, operators often regard traditional fullband tunable modules as expensive for this application. Mobile fronthaul links don’t need anything close to the 40 or 80 DWDM channels of a fullband transceiver. It’s like having a cable subscription where you only watch 10 out of the 80 TV channels.

This issue led EFFECT Photonics to develop narrowband tunable modules with just nine channels. They offer a more affordable and moderate capacity expansion that better fits the needs of mobile fronthaul networks. These networks often feature nodes that aggregate two or three different cell sites, each with three antenna arrays (each antenna provides 120° coverage at the tower) with their unique wavelength channel. Therefore, these aggregation points often need six or nine different wavelength channels, but not the entire 80-100 channels of a typical fullband module.

With the narrowband tunable option, operators can reduce their part number inventory compared to grey transceivers while avoiding the cost of a fullband transceiver.

Synergizing with Self-Tuning Algorithms

The number of channels in a tunable module (up to 100 in the case of EFFECT Photonics fullband modules) can quickly become overwhelming for technicians in the field. There will be more records to examine, more programming for tuning equipment, more trucks to load with tuning equipment, and more verifications to do in the field. These tasks can take a couple of hours just for a single node. If there are hundreds of nodes to install or repair, the required hours of labor will quickly rack up into the thousands and the associated costs into hundreds of thousands.

*Figure 4: Short description and comparison of different approaches to DWDM tunable modules.*

Self-tuning allows technicians to treat DWDM tunable modules the same way they treat grey transceivers. There is no need for additional training for technicians to install the tunable module. There is no need to program tuning equipment or obsessively check the wavelength records and tables to avoid deployment errors on the field. Technicians only need to follow the typical cleaning and handling procedures, plug the transceiver, and the device will automatically scan and find the correct wavelength once plugged. This feature can save providers thousands of person-hours in their network installation and maintenance and reduce the probability of human errors, effectively reducing capital and operational expenditures.

Self-tuning algorithms make installing and maintaining narrowband and fullband tunable modules more straightforward and affordable for network deployment.

Takeaways

Fullband self-tuning modules will allow providers to deploy extensive fiber capacity upgrades more quickly than ever. However, in use cases such as mobile access networks where operators don’t need a wide array of DWDM channels, they can opt for narrowband solutions that are more affordable than their fullband alternatives. By combining fullband and narrowband solutions with self-tuning algorithms, operators can expand their networks in the most affordable and accessible ways for their budget and network requirements.

Tags: 100G, 5G, 6G, access, access networks, aggregation, backhaul, capacity, coherent, DWDM, fronthaul, Integrated Photonics, LightCounting, live events, metro, midhaul, mobile, mobile access, mobile networks, network, optical networking, optical technology, photonic integrated chip, photonic integration, Photonics, PIC, PON, programmable photonic system-on-chip, solutions, technology, VR, WDM

Technologies and trends and their impact

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September 1, 2022

Scaling Up Live Event Coverage with 5G Technology

Everyone who has attended a major venue or event, such as a football stadium or…

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August 24, 2022

What’s Inside a Coherent DSP?

Coherent transmission has become a fundamental component of optical networks to address situations where direct…

Coherent transmission has become a fundamental component of optical networks to address situations where direct detect technology cannot provide the required capacity and reach.

While direct detect transmission only uses the amplitude of the light signal, coherent optical transmission manipulates three different light properties: amplitude, phase, and polarization. These additional degrees of modulation allow for faster optical signals without compromising the transmission distance. Furthermore, coherent technology enables capacity upgrades without replacing the expensive physical fiber infrastructure on the ground.

The digital signal processor (DSP) is the electronic heart of coherent transmission systems. The fundamental function of the DSP is encoding the electronic digital data into the amplitude, phase, and polarization of the light signal and decoding said data when the signal is received. The DSP does much more than that, though: it compensates for impairments in the fiber, performs analog-to-digital conversions (and vice versa), corrects errors, encrypts data, and monitors performance. And recently, DSPs are taking on more advanced functions such as probabilistic constellation shaping or dynamic bandwidth allocation, which enable improved reach and performance.

Given its vital role in coherent optical transmission, we at EFFECT Photonics want to provide an explainer of what goes on inside the DSP chip of our optical transceivers.

There’s More to a DSP Than You Think…

Even though we colloquially call the chip a “DSP”, it is an electronic engine that performs much more than just signal processing. Some of the different functions of this electronic engine (diagram below) are:

*Figure 1: Layout of the electronic engine used in a coherent optical transceiver, including the sequence the signal follows when processed by the engine.*

Analog Processing: This engine segment focuses on converting signals between analog and digital formats. Digital data is composed of discrete values like 0s and 1s, but transmitting it through a coherent optical system requires converting it into an analog signal with continuous values. Meanwhile, a light signal received on the opposite end requires conversion from analog into digital format.
Digital Signal Processing: This is the actual digital processing. As explained previously, this block encodes the digital data into the different properties of a light signal. It also decodes this data when the light signal is received.
Forward Error Correction (FEC): FEC makes the coherent link much more tolerant to noise than a direct detect system and enables much longer reach and higher capacity. Thanks to FEC, coherent links can handle bit error rates that are literally a million times higher than a typical direct detect link. FEC algorithms allow the electronic engine to enhance the link performance without changing the hardware. This enhancement is analogous to imaging cameras: image processing algorithms allow the lenses inside your phone camera to produce a higher-quality image.

Figure 2: Simplified diagram of a network link with forward error correction (FEC). The FEC encoder adds a series of redundant bits (called overhead) to the transmitted data stream. The receiver can use this overhead to check for errors without asking the transmitter to resend the data.

Framer: While a typical electric signal sent through a network uses the Ethernet frame format, the optical signal uses the Optical Transport Network (OTN) format. The framer block performs this conversion. We should note that an increasingly popular solution in communication systems is to send Ethernet frames directly over the optical signal (a solution called optical Ethernet). However, many legacy optical communication systems still use the OTN format, so electronic engines should always have the option to convert between OTN and Ethernet frames.
Glue Logic: This block consists of the electronic circuitry needed to interface all the different blocks of the electronic engine. This includes the microprocessor that drives the electronic engine and the serializer-deserializer (SERDES) circuit. Since coherent systems only have four channels, the SERDES circuit converts parallel data streams into a single serial stream that can be transmitted over one of these channels. The opposite conversion (serial-to-parallel) occurs when the signal is received.

We must highlight that each of these blocks has its own specialized circuitry and algorithms, so each is a separate piece of intellectual property. Therefore, developing the entire electronic engine requires ownership or access to each of these intellectual properties.

So What’s Inside the Actual DSP Block?

Having clarified first all the different parts of a transceiver’s electronic engine, we can now talk more specifically about the actual DSP block that encodes/decodes the data and compensates for distortions and impairments in the optical fiber. We will describe some of the critical functions of the DSP in the order in which they happen during signal transmission. Receiving the signal would require these functions to occur in the opposite order, as shown in the diagram below.

*Figure 3. Layout of the digital signal processing blocks and the sequence followed by the signal when transmitted and received.*

Signal Mapping: This is where the encoding/decoding magic happens. The DSP maps the data signal into the different phases of the light signal—the in-phase components and the quadrature components—and the two different polarizations (x- and y- polarizations). When receiving the signal, the DSP will perform the inverse process, taking the information from the phase and polarization and mapping it into a stream of bits. The whole process of encoding and decoding data into different phases of light is known as quadrature modulation. Explaining quadrature modulation in detail goes beyond the scope of this article, so if you want to know more about it, please read the following article.
Pilot Signal Insertion: The pilot signal is transmitted over the communication systems to estimate the status of the transmission path. It makes it easier (and thus more energy-efficient) for the receiver end to decode data from the phase and polarization of the light signal.
Adaptive Equalization: This function happens when receiving the signal. The fiber channel adds several distortions to the light signal (more on that later) that change the signal’s frequency spectrum from what was initially intended. Just as with an audio equalizer, the purpose of this equalizer is to change specific frequencies of the signal to compensate for the distortions and bring the signal spectrum back to what was initially intended.

*Figure 4: How the equalizer in a communication systems work. The example in this figure is an equalizer for RF coaxial transmission (not optical), but the principle is the same. Source:* *Broadband Library*

Dispersion and Nonlinear Compensation: This function happens when receiving the signal. The quality of the light signal degrades when traveling through an optical fiber by a process called dispersion. The same phenomenon happens when a prism splits white light into several colors. The fiber also adds other distortions due to nonlinear optical effects. These effects get worse as the input power of the light signal increases, leading to a trade-off. You might want more power to transmit over longer distances, but the nonlinear distortions also become larger, which beats the point of using more power. The DSP performs several operations on the light signal that try to offset these dispersion and nonlinear distortions.
Spectrum Shaping: Communication systems must be efficient in all senses, so they must transmit as much signal as possible within a limited number of frequencies. Spectrum shaping is a process that uses a digital filter to narrow down the signal to the smallest possible frequency bandwidth and achieve this efficiency.

When transmitting, the signal goes through the digital-to-analog conversion after this whole DSP sequence. When receiving the signal, it goes through the inverse analog-to-digital conversation and then through the DSP sequence.

Recent Advances and Challenges in DSPs

This is an oversimplification, but we can broadly classify the two critical areas of improvement for DSPs into two categories.

Transmission Reach and Efficiency

The entire field of communication technology can arguably be summarized with a single question: how can we transmit more information into a single frequency-limited signal over the longest possible distance?

DSP developers have many tools in their kit to answer this question. For example, they can transmit more data using more states in their quadrature-amplitude modulation process. The simplest kind of QAM (4-QAM) uses four different states (usually called constellation points), combining two different intensity levels and two different phases of light.

By using more intensity levels and phases, more bits can be transmitted in one go. State-of-the-art commercially available 400ZR transceivers typically use 16-QAM, with sixteen different constellation points that arise from combining four different intensity levels and four phases. However, this increased transmission capacity comes at a price: a signal with more modulation orders is more susceptible to noise and distortions. That’s why these transceivers can transmit 400Gbps over 100km but not over 1000km.

One of the most remarkable recent advances in DSPs to increase the reach of light signals is probabilistic constellation shaping (PCS). In the typical 16-QAM modulation used in coherent transceivers, each constellation point has the same probability of being used. This is inefficient since the outer constellation points that require more power have the same probability as the inner constellation points that require lower power.

*Figure 5: Comparison of conventional 16-QAM and a 16-QAM that uses probabilistic constellation shaping (PCS). Original diagram source:* *Infinera*.

PCS uses the low-power inner constellation points more frequently, and the outer constellation points less frequently, as shown in Figure 5. This feature provides many benefits, including improved tolerance to distortions and easier system optimization to specific bit transmission requirements. If you want to know more about it, please read the explainers here and here.

Energy Efficiency

Increases in transmission reach and efficiency must be balanced with power consumption and thermal management. Energy efficiency is the biggest obstacle in the roadmap to scale high-speed coherent transceivers into Terabit speeds.

Over the last two decades, power ratings for pluggable modules have increased as we moved from direct detection to more power-hungry coherent transmission: from 2W for SFP modules to 3.5 W for QSFP modules and now to 14W for QSSFP-DD and 21.1W for OSFP form factors. Rockley Photonics researchers estimate that a future electronic switch filled with 800G modules would draw around 1 kW of power just for the optical modules.

Figure 6: 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 valid for various DSP-based modules, both IM-DD and coherent. Source: *R. Nagarajan et al., IEEE JLT (2021)*

Around 50% of a coherent transceiver’s power consumption goes into the DSP chip. Scaling to higher bandwidths leads to even more losses and energy consumption from the DSP chip, and its radiofrequency (RF) interconnects with the optical engine. DSP chips must therefore be adaptable and smart, using the least amount of energy to encode/decode information. You can learn more about this subject in one of our previous articles. The interconnects with the optical engine are another area that can see further optimization, and we discuss these improvements in our article about optoelectronic co-design.

Takeaways

In summary, DSPs are the heart of coherent communication systems. They not only encode/decode data into the three properties of a light signal (amplitude, phase, polarization) but also handle error correction, analog-digital conversation, Ethernet framing, and compensation of dispersion and nonlinear distortion. And with every passing generation, they are assigned more advanced functions such as probabilistic constellation shaping.

There are still many challenges ahead to improve DSPs and make them transmit even more bits in more energy-efficient ways. Now that EFFECT Photonics has incorporated talent and intellectual property from Viasat’s Coherent DSP team, we hope to contribute to this ongoing research and development and make transceivers faster and more sustainable than ever.

Tags: 100G, 5G, 6G, access, access networks, aggregation, backhaul, capacity, coherent, DWDM, fronthaul, Integrated Photonics, live events, metro, midhaul, mobile, mobile access, mobile networks, network, optical networking, optical technology, photonic integrated chip, photonic integration, Photonics, PIC, PON, programmable photonic system-on-chip, solutions, technology, VR, WDM

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August 10, 2022

The Next Bright Lights of Eindhoven

Paris may be the more well-known City of Light, but we may argue that Eindhoven…

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July 14, 2022

Photonic System-on-Chip is the Future

Before 2020, Apple made its computer processors with discrete components. In other words, electronic components…

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 different chips produced losses and incompatibilities that made the device less efficient. After 2020, starting with Apple’s M1 processor, they now fully integrate all components on a single chip, avoiding losses and incompatibilities.

Apple’s fully integrated processor consumes a third of the power and lower costs than their older processors while still providing similar performance. EFFECT Photonics does something similar to what Apple did, but with optical components instead of electronic components. By integrating all the optical components (lasers, detectors, modulators, etc.) in a single system on a chip, we can minimize the losses and make the device more efficient. This approach is what we call photonic System-on-Chip (SoC).

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. Testing is another aspect that becomes more efficient and scalable when manufacturing at the wafer level.

When faults are found earlier in the testing process, fewer resources and energy are spent processing defective chips. Ideally, testing should happen not only on the final, packaged transceiver but in the earlier stages of photonic SoC fabrication, such as measuring after wafer processing or cutting the wafer into smaller dies. Full photonic integration 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 time, and cost and is more energy-efficient and sustainable.

Figure 2: Package vs. die level testing. Manufacturers can find faults earlier by testing at the die level, avoiding wasting packaging materials.

For example, EFFECT Photonics reaps these benefits in its production processes. 100% of electrical testing on the photonic SoCs happens at the wafer level, and our unique integration technology allows for 90% of optical testing on the wafer. The real-world applications of SoCs are practically limitless and priceless. Electronic SoCs are used in most, if not all, portable devices, such as smartphones, cameras, tablets, and other wireless technologies. SoCs are also frequently used in equipment involved in the Internet of Things, embedded systems, and, of course, photonics. Data center interconnects are an excellent example of an application that benefits from a photonic SoC approach. As DCIs demand higher performance and reach, it’s no longer sufficient to have a solution that integrates just some parts of a system.

That is why EFFECT Photonics’ business strategy aims to solve the interconnect challenges through a holistic photonic SoC approach that understands the interdependence of system elements. By combining the photonic SoC with highly optimized packaging with cost-effective electronics, we are building a high production volume platform that can meet the demands of the datacom sector.

Tags: DWDM, Integrated Photonics, network, optical networking, optical technology, photonic integrated chip, photonic integration, photonic system-on-chip, PIC, solutions, technology

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July 7, 2022

The Growth of Business Ethernet Services

The increasing use of data and fiercely price-conscious and multimedia-hungry business subscribers can limit revenue…

The increasing use of data and fiercely price-conscious and multimedia-hungry business subscribers can limit revenue opportunities for the network provider industry. Providers must therefore look elsewhere to grow their customer base, open new revenue streams, and boost margins. So how can they adapt their business strategies and achieve growth objectives?

Just as operators scale up high-capacity data center interconnects to cope with these needs, providers can add Ethernet services for high-capacity services. These can offer a differentiated and competitive service to corporate customers, ranging from 1G to 100G and beyond. Not only will Ethernet services add a cost-effective alternative to existing services, but they also ensure business Ethernet offerings are set up to complement wide area networks and hybrid network services.

According to Ovum, the global enterprise Ethernet services market will grow at 10.7% CAGR, exceeding $70bn by 2020 (Ovum’s Ethernet Services Forecast, Sep 2015), and is now the de facto wide-area network data connectivity technology. Ethernet will be a significant portion of the data service market driven by enthusiasm for higher bandwidth services. This growth will continue as we adopt more cloud-based applications and enterprises embrace digital transformation. Business Ethernet solutions can be further boosted with tunable DWDM transceivers.

Towards Carrier Ethernet

With applications and data volumes exploding in organizations of all types and sizes, there is an increasing need for 1GbE+ connections, with 10GbE+ connectivity for company headquarters and even 100GbE+ connections for data center connectivity. Specifically, demand is being driven by the proliferation of bandwidth-hungry applications. An MRI scan, for example, can be a 300GB file, which would take around 7 hours to download over a 100Mbps connection. Over a 10GbE link, that time falls to just 4 minutes and 28 seconds on a 100GbE link – this can be the difference between life and death when a consultant needs to make a time-critical decision on how to treat their patient best.

Enterprises know all about cost-containment and budget constraints. Virtual private networks (VPNs) based on legacy MPLS protocols have their place when delivering wide-area connectivity. These VPNs can offer any-to-any connectivity and scale to thousands of sites – but, at the higher speeds needed for high-bandwidth applications, they can be significantly more expensive than business Ethernet to deploy and maintain.

In addition, the MPLS routers needed for IP VPN have acquired more and more protocols and complexity over the last few decades. The cost of implementing all of these protocols, and securing them against attack, has driven leading service providers to demand a radically more straightforward way of building networks.

With business Ethernet, the network infrastructure and management can be unified under Ethernet protocol, making the network easier to plan, deploy and manage at scale. This means fewer routers, more remotely programmable services, and fewer truck rolls resulting in a lower cost per bit than comparable VPN solutions. These savings scale across 1GbE, 10GbE, and 100GbE connections with less CAPEX investment, helping to increase the predictability of delivery costs over time. WDM solutions can further boost this capacity.

Towards a Coherent Upgrade with 100ZR

Almost every organization uses the cloud in some capacity, whether for development and test resources or software-as-a-service applications. While the cost and flexibility of the cloud are compelling, many IT executives overlook the importance of fast, high-bandwidth wide-area connectivity to make cloud-based applications work as they should.

These needs might require businesses with huge traffic loads to upgrade to 25G, 100G, or even 400G speeds. These capacity needs would require coherent technology. Fortunately, advances in electronic and photonic integration have miniaturized coherent line card transponders into pluggable modules the size of a large USB stick.

Many of these business applications will require links between 25 Gbps and 100 Gbps that span several tens of kilometers to connect to the network provider’s headend. For these sites, the 400ZR pluggables that have become mainstream in datacom applications are not cost-effective when utilization is so low. This is where 100ZR technology comes into play.

100ZR is currently a marketing term for a short-reach (~80 km) coherent 100Gbps in a QSFP pluggable. Targeted at the metro edge and enterprise applications that do not require 400Gbps, 100ZR provides a lower-cost, lower-power pluggable that also benefits from compatibility with the large installed base of 50 GHz and legacy 100 GHz DWDM/ROADM line systems.

Self-Tuning Makes Management Easier

Businesses that need to aggregate many sites and branches into their networks will likely require tunable transceiver solutions to interconnect them. The number of available channels in tunable modules can quickly become overwhelming for technicians in the field. There will be more records to examine, more programming for tuning equipment, more trucks to load with tuning equipment, and more verifications to do in the field. These tasks can take a couple of hours just for a single node. If there are hundreds of nodes to install or repair, the required hours of labor will quickly rack up into the thousands and the associated costs into hundreds of thousands. Self-tuning modules significantly overcome these issues and make network deployment and maintenance more straightforward and affordable.

Self-tuning allows technicians to treat DWDM tunable modules the same way they would grey transceivers. There is no need for additional training for technicians to install the tunable module. There is no need to program tuning equipment. There is no need to obsessively check the wavelength records and tables to avoid deployment errors on the field. Technicians only need to follow the typical cleaning and handling procedures, plug the transceiver, and the device will automatically scan and find the correct wavelength once plugged. This feature can save providers thousands of person-hours in their network installation and maintenance and reduce the probability of human errors, effectively reducing capital and operational expenditures (OPEX).

Takeaways

With business Ethernet, one can set up super-fast connections for customers and connect their locations and end-users with any cloud-based services they use. Business Ethernet solutions can be further boosted with tunable DWDM transceivers. If business future-proof their networks with upgrades like 100ZR transceivers, they can scale up connectivity seamlessly to ensure that applications always provide an excellent end-user experience. That connectivity is never a limiting factor for customers’ cloud strategies. As the business sector seeks to upgrade to greater capacity and easier management, tunable and coherent transceivers will be vital in addressing their needs.

Tags: 5G, access, aggregation, backhaul, capacity, DWDM, fronthaul, Integrated Photonics, LightCounting, metro, midhaul, mobile, mobile access, network, optical networking, optical technology, photonic integrated chip, photonic integration, PIC, PON, programmable photonic system-on-chip, solutions, technology

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External and Integrated Lasers: What’s the Difference?

What are the key requirements for a laser in coherent systems?

The Promise of Multi-Laser Arrays

Takeaways

From World-Class Labs to the Real World

From the Mill to High Tech: The Story of Maynard

What’s the most exciting thing about joining EFFECT Photonics?

What key technology challenges must be solved by DSP designers to thrive in the next 5 to 10 years?

How do you think the DSP can be more tightly integrated with the PIC?

What are the challenges and opportunities of designing DSPs for Indium phosphide instead of silicon?

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The Advantages of WDM PONs

The Possibility of Coherent Access

Combining Affordable Designs with Affordable Manufacturing

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Example: Fullband Tunables in Cable Networks

Example: Narrowband Tunables in Mobile Fronthaul

Synergizing with Self-Tuning Algorithms

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A Higher Bandwidth Experience

New Ways of Interaction

Strengthening the Transport Network

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There’s More to a DSP Than You Think…

So What’s Inside the Actual DSP Block?

Recent Advances and Challenges in DSPs

Transmission Reach and Efficiency

Energy Efficiency

Takeaways

From Matches to the Light Bulb Factory

From ASML and Photonics Research to Philips

Bringing Photonics into the Real World from the Lab

Towards Carrier Ethernet

Towards a Coherent Upgrade with 100ZR

Self-Tuning Makes Management Easier

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