SiDx's use of silicon photonics for blood testing
Part 4: Biosensor start-up, SiDx
A blood sample reveals much about a person’s health. But analysing the sample is complicated given its many constituents.
Identifying a user’s blood type is also non-trivial.
If a patient arriving at hospital needs a blood transfusion, the universal donor blood type, O negative, is administered. That’s because it takes too long – 45 minutes typically – to identify the patient’s blood type. This also explains the huge demand for O negative blood.
Identifying blood type promptly is what start-up SiDx set out to address with a platform based on a silicon photonics sensor. The resulting platform does more than just blood-type identification.
SiDx
The Seattle-based start-up was founded in 2017. By then, SiDx had a decade of research behind it, in silicon-photonics biosensors and the associated biochemistry.
SiDx had also started working with a blood centre in Seattle. Such centres source and sell blood to US hospitals.
“We were looking for an application that justified starting the company,” says Jonas Flueckiger, vice president of engineering at SiDx.
Flueckiger notes that silicon photonics is one of several ways to analyse biological materials. “It has advantages but there are alternatives,” he says. “You have to find an application where the advantages of silicon photonics can shine.”
Marketplace and challenges
Flueckiger splits the biosensor marketplace into three: centralised lab equipment, bedside and portable equipment, and home testing.
For centralised labs, what matters is the scale and the ability to perform parallel testing. Here, trained staff are required for sample preparation and operating the equipment.
The second category, bedside and portable systems, are compact and rugged platforms designed to deliver results quickly; SiDx’s testing system takes 12 minutes. Such platforms are newer and are the focus of SiDx and other silicon photonics biosensor start-ups.
“As for home tests, you don’t need a doctor’s office, you can do it yourself,” says Flueckiger.
But medical diagnostics is a challenging market to enter. “The biggest challenge is that it is very, very hard to bring something new into the medical space,” says Flueckiger.
Hospitals are conservative establishments with rigid protocols that have test systems that doctors trust.
“Even though you show your system will be better, more efficient, faster, and the patient will be better served, it is still very hard to make a case to replace existing technology in a hospital,” says Flueckiger.
A new biosensor system must show it saves money, almost as important as demonstrating improved performance. “If your device is better but it costs more, that is not enough,” says Flueckiger.
Even if a start-up develops a system comparable in price, it must displace existing processes. And that raises a series of questions. Who does the testing? Where do the test results go? And who delivers the news to the patient?
“It is a complex picture and it is not just about technology,” says Flueckiger.
Ring resonators
SiDx’s silicon photonics platform measures refractive index changes in light caused by blood sample components attaching to ‘receptors’ placed on the sensor’s surface.
Biochemistry is required to design the receptors for blood analysis and is a core expertise of SiDx.
SiDx uses a laser coupled to a ring resonator. When blood sample constituents attach to the receptors on the ring resonator’s surface, the wavelength at which the sensor resonates changes. This shift in refractive index is used to identify the constituents. (See diagram above.)
A key benefit of the ring resonator approach is its tiny size. Multiple sensors can be integrated into a compact area allowing tests to be performed in parallel. Or as Flueckiger puts it, there is an ability to ask more than one question.
SiDx says it uses ring resonators but it is not detailing its design.
Most emerging integrated-photonics biosensing companies use a laser and ring resonator to read refractive index changes.
One way of get readings is using a tunable laser but alternative designs are possible such as using a fixed laser and tuning the resonator.
That is possible, says Flueckiger, but in a multiplexed design where multiple ring resonators are used, the electrical input-output for all the resonators gets tricky.
“Even for a single test, a single marker, you will have a negative control, a positive control, usually one or two more to make sure you have what you think you have,” says Flueckiger. “With bodily fluids like blood, it is complex and includes stuff that can interfere.”
Silicon photonics also enables label-free detection.
Here, only receptors are used to catch a blood constituent of interest. There is no need for labels with fluorescent attachments designed to link to the constituent.
But labelling improves the probability of identifying what is being looked for. Blood is so complex a sample that doctors may not want label-free testing for just this reason, the risk that another biomarker gives a similar response to what is being sought.
SiDx says sample preparation is key here. Rather than simply squirting the blood sample into the device, additional steps are used such as dilution or separating red blood cells from the serum with testing performed on either. Reagents can also be added to remove all the cells’ membranes.
Such sample preparation steps before label-free testing are important and non-trivial. “Photonics, that is the easy part,” says Flueckiger.
The resulting biosensor comprises optics and biology. Yet it requires a shelf life of 6-12 months. Another reason why medical biosensor design – and the biochemistry in particular – is challenging.
Blood testing and disease screening
Most people understand major blood types such as A, B, AB or O negative, says Flueckiger. But it is more complicated than that in that there are many subgroups. If they are assessed wrongly, it can prove harmful to a patient.
SiDx’s platform can perform blood typing and also Rhesus tests during pregnancy. Rhesus disease is caused by a certain mix of blood types between a pregnant mother and the unborn child.
SiDx sees blood typing as an entry to the market: to prove its technology before branching out. “Once you have blood typing and a sample, you can expand the test portfolio,” says Flueckiger.
The aim is to group tests in an offering that make sense. For example, testing for covid-19 but also testing for the common flu. Or, if a patient tests negative for covid-19, what else could it be? Testing that way and getting an answer avoids the need for a second test.
There are multiple ways to test for covid-19.
A PCR test looks for the DNA of the virus. Analysing a blood sample determines if a body’s immune response has developed antibodies to the virus. If so, it means the person has, or has had, covid-19. SiDx’s biosensor will also be able to test a person’s immune system after a vaccine and determine if a booster jab is needed.
SiDx’s system can detect DNA, but an issue is that DNA needs ‘amplification’; its levels are too small otherwise.
Using integrated photonics coupled with the right capture molecules on the surface allows what is captured to be detected. A DNA molecule is much smaller so other tricks are needed to measure it. As a result, antibodies are more commonly tested for because it is much easier, says Flueckiger.
Prospects
SiDx along with other silicon photonics biosensor companies such as Genalyte, SiPhox, Rockley Photonics and Antelope DX, all received recent funding rounds. SiDx has raised a total of $3 million in funding and $2 million in research funding.
Is this not a vote of confidence in what is a tough market to crack?
There is venture money but it is hard to come by, says Flueckiger. Developing a medical device takes time, a minimum of five years before getting somewhere. If a company starts from scratch, the development time is longer than what venture capitalists are happy with.
Companies pursuing blood testing also can expect greater scrutiny given the story of private company, Theranos, whose claims about developing a breakthrough blood analysis system proved false.
Venture capitalists recognise the potential of benchtop devices but their concern is making money and how quickly a start-up can multiply their investment.
“Unless you can show hockey-stick growth, it’s a tough sell,” says Flueckiger. “These are long-term investments, not like a software company.”
That said, the covid-19 pandemic has helped. People now understand the important role such diagnostic equipment can play. They recognise how long it takes and that if money is thrown at the problem, device development can be accelerated.
Despite the challenges, Flueckiger is upbeat. “We have made lots of progress,” he says. “We have proven to ourselves that our technology works.” SiDx says there are developments that bring its platform closer to market that it cannot disclose at present.
The coronavirus pandemic also provided the company with a motivational boost to launch a product that is far easier to use.
SiDx did consider shifting its focus to address covid-19 testing but the pandemic occurred a year too early. “If it happened now, we would be in a lot better position to turn around very quickly with limited money and have a test ready,” says Flueckiger.
SiDx says that its conversations with investors generate excitement but they want proof of a return.
“You go into this knowing you have a long runway – the next five years will be hard – and then there is the question of whether you will be successful or not,” says Flueckiger.
imec’s research work to advance biosensors
Part 3: Biosensor developments
- Pol Van Dorpe discusses the institute’s use of photonics and silicon to develop new designs for medical diagnostics.
- imec has designed a breathalyser that detects the coronavirus with the accuracy of a polymerase chain reaction (PCR) test, a claimed world first.
Optics and photonics are advancing medical diagnostics in two notable ways.
The technologies are helping to shrink diagnostic systems to create new types of medical devices.
“Going from big lab equipment to something much smaller is a clear trend,” says Pol Van Dorpe, a Fellow at imec, the Belgium R&D nanoelectronics and nanotechnology institute.
Photonics and silicon also benefit central labs by creating more powerful test instruments. More functionality and detectors can be integrated in a given area enabling multiple tests in parallel, a technique dubbed multiplexing.
imec’s biosensor work and espertise
imec began its biosensor research in the 1990s, investigating electrical and surface plasmon-based devices. In more recent years, it has added the development of custom biosensor chips for companies.
As examples, imec worked with Panasonic to develop a chip for PCR, a testing technique now known to the public due to covid-19. The R&D institute also worked with Genalyte, a pioneering silicon photonics medical diagnostics company that uses optical waveguides, ring resonators, and a tunable laser for its multiplexing biosensor product.
imec has also developed in-house expertise across several disciplines needed for biosensor development.
Several groups at imec cover photonics, with Van Dorpe heading the group addressing biophotonics and single-molecule electrical devices.
Another group addresses biochemistry and surface chemistry used to coat and activate a sensor’s surface so that receptors can be attached. Receptors are biochemical materials that enable the sensor to trap and detect materials.
A further team covers microfluidics used to deliver liquid samples to the sensor or to mix solutions precisely.
Semiconductor process steps are used to create high-aspect-ratio structures that implement microfluidic structures. Such structures can also be used to sort cells, known as cytometry.
“There are many sensor types, and each has its own fluidic needs,” says Van Dorpe.
Spin-offs
imec has also spun off several biosensor companies.
One, miDiagnostics, raised $16.5 million in funding in 2020. miDiagnostics has a nanofluidic processor (nFP) that performs diagnostic tests on fluids guided through the system using capillary forces. The liquids can be redirected and can even have their flow reversed.
The nFP is configurable depending on the application. It combines nanofluidic processing and PCR for processing biomarkers: from cells and proteins to nucleic acids and small molecules.
Indigo is another spin-off that is developing a glucose monitoring system. A photonics sensor is embedded under the skin and communicates the user’s blood sugar level to a smartphone.
Market trends
The biosensor market is complex. Many actors – labs, doctors and users – in healthcare must be convinced before adopting a biosensor device. For a device to be successful, it must add value compared to existing equipment. Cost is also key as is the use-case and ease of use.
Portable equipment that delivers results promptly so that medical staff can make quick decisions is one example. Others include identifying if a patient has suffered a heart attack or bacterial infections such as sepsis, or enabling a doctor’s office to determine if a patient has a bacterial or viral infection. But no doctor will have 20 devices in their office, each performing a specific test, he says.
Such biosensor devices could also have played a key role during the current coronavirus pandemic.
“I can tell you we were working with companies and if they were several years ahead in their roadmaps, much of this would have been a lot easier,” says Van Dorpe.
Antigen-based quick tests for covid exist but people don’t trust them completely due to their limited sensitivity. It is also still not known when people become contagious. “If you take a nasal swab but are already recovering then you may not be as contagious,” says Van Dorpe.
imec has developed a coronavirus breathalyser. Blowing into a filter, aerosols and small droplets from a person’s lungs are collected. A 5-minute PCR analysis unit delivers a result, informing the person if their breath is infectious.
The goal is to use such systems at airports and large events, but it doesn’t guarantee that a person won’t get sick. “You could have been infected the previous day,” says Van Dorpe.
In clinical trials with UZ Leuven, the university hospital of Leuven, the system has tested viral RNA in exhaled air with high sensitivity.
“Our chip technology can detect quickly the virus particles with the same accuracy as classical PCR tests,” says Van Dorpe. “We are the first in the world to demonstrate this.”
imec is undertaking more clinical trials while improving the test’s robustness and ease of use. “We are discussing the commercialisation of our technology with different parties,” he says.
Biosensor technologies
imec’s toolbox of technologies include silicon nitride optical waveguides, beam splitters, filters, spectrometers, and in-plane and out-of-plane lenses.
imec can deposit waveguides on CMOS and has exploited the technique with CMOS image sensors that have many detectors. “We can use commercial image-sensor wafers and deposit the waveguide technology and use those pixels as detectors,” says Van Dorpe.
Established diagnostic techniques used in medical labs include ELISA, a reference technique to detect proteins, and PCR that tests for nucleic acid detection (DNA/ RNA).
The importance of both lab techniques will not change anytime soon, says Van Dorpe.
One reason why ELISA and PCR are so established is that they use ‘amplification’ to detect minute amounts of the material being tested for – the analyte – in complex samples.
For amplification, another label is used in addition to the receptors. The analyte is attached to an antibody within the label, and it is this second label that provides greater testing sensitivity. This, however, requires sample preparation by trained staff.
In contrast, newer biosensors technologies such as surface plasmon resonance (SPR) and silicon photonics use a label-free approach that does away with the second analyte-label stage.
But the label-free sensor is less sensitive; the technique measures when something attaches to the receptors but it can’t distinguish what it measures.
Van Dorpe stresses that amplification is chemistry-related and so it can be used with silicon photonics or SPR.
It is the overall diagnostic system that determines sensitivity, the combination of the transduction process and the chemistry, says Van Dorpe.
SPR and silicon photonics
SPR and silicon photonics biosensors work by measuring changes in light caused by passing a sample over the sensor which causes molecules to attach to the surface.
An SPR system comprises a laser, a prism attached to a gold surface, and a detector. Light is shone through the prism and is reflected from the gold layer before being detected. At a certain incident angle, the light causes electron resonance on the gold surface causing the reflected light intensity to dip.
Attaching biochemical receptors to the gold surface tailored to the analyte causes a shift in resonance angle and the angle change is a measure of the analyte’s presence.
In contrast, silicon photonic designs measure refractive index changes in the light caused by analytes attached to receptors on the sensor’s surface. Two sensor designs are used: a laser with either a Mach-Zehnder interferometer (MZI) or a ring resonator.
“Everything that changes the refractive index causes a signal,” says Van Dorpe.
imec’s biosensor developments
imec’s work with Genalyte a decade ago involved a biosensor that used a tunable laser and ring-resonator sensors.
More recently, the R&D institute has developed technologies not reflected in the silicon photonics designs used by biosensor start-ups such as Genalyte, SiDx, Antelope DX and SiPhox.
imec’s biosensor technologies have been developed to be less sensitive to non-specific binding. What is measured is fluorescence that occurs with the binding to the analyte.
“In blood or more complicated samples, there is a lot of stuff [besides what is being tested for],” says Van Dorpe.
One technology imec has developed performs rapid ELISA-style testing without needing the repeated wash stages required with ELISA systems.
ELISA uses an antibody receptor to detect the tested-for material while a second antibody uses an enzyme that produces colour. And it is the colour that is measured. In effect, both antibodies detect the analyte but the second, with its fluorescent label, helps determine how much analyte has bound.
With standard ELISA testing, repeated wash steps are required to remove what has not bound to the receptors and labels. These wash stages lengthen the testing time.
imec’s sensor is sensitive in the region very close to the surface. Measuring the fluorescence near the surface determines its build-up over time (see diagram).
The cleverness of the sensor is that the larger the concentration, the faster the surface fills up, reflected in the rate of change of fluorescence over time.
“You don’t need to wait until everything has stabilised to determine the concentration,” says Van Dorpe. “You can wait, say 2 minutes, measure the slope of the signal and that gives you a direct measure of the concentration.”
The design can be used with blood samples, to measure protein production or proteins that shouldn’t be there.
The sensor allows the real-time measurement of biomarkers, and no wash stages are needed. It also enables a controlled process for the biological production of vaccines or cancer therapy.
The key here is that using waveguides and integrated photonics allows localised sensing.
“Also with waveguide technology, because you route light on a chip, you can address a lot of [sensing] sites at the same time,” says Van Dorpe. “That allows you to measure a lot of spots, what is called multiplexing.”
These are the advantages of integrated photonics: the ability to test in parallel and the precise quantification of concentrations, he says.
imec has developed a second fluorescence technique – called super-critical angled fluorescence – closely related to the first but that does away with the waveguide.
As with the first technique, two antibodies are used, one with a fluorescent label.
By exciting the fluorescent label, light is produced in all directions. If a high-angle beam is used, the light at the surface interface refracts within a critical angle.
A fluorescent molecule close to the surface – less than a wavelength away – emits light into a silicon-oxide material. This helps distinguish molecules far from the surface compared to closer ones.
imec’s compact system filters out fluorescence from labels floating further away while measuring those nearby. This is like what happens with the waveguide of the first technique, where it is routed to the detector. But here the detector is situated underneath to measure the fluorescence. The technique delivers rapid results.
The two imec techniques deliver selective sensing that doesn’t rely on refractive index changes or mass. With the latter techniques, all the signals are picked up: everything that binds, wanted and unwanted materials.
The imec techniques are not perfect. There is some degree of auto-fluorescence but it is low. Also, some antibodies with the label will bind to the surface but that is much smaller than the proteins, says Van Dorpe.
Cytometry
imec is working with Sarcura, a cell therapy firm, on a high-throughput cytometry solution for cell separation. Here photonic integration is used along with a microfluidic solution to measure the cells.
A standard cytometer has a flow of cells and a bank of lasers at multiple wavelengths typically. As the cells pass, they scatter the focused light from the lasers. The scattering is measured while the cells also fluoresce since they are labelled. This allows for cell categorisation.
With cell therapy for cancer treatment, immune cells are grown and need analysing. Another use is identifying tumour cells in the blood.
“There are lots of applications where you want to pick out specific cells, label them, look at their properties and classify,” he says.
Traditional equipment used for these tasks is large and complex, requiring skilled staff.
What silicon photonics and microfluidics allow is the bringing of cells to the channel and, with waveguides, illuminate them and detect them.
The result, says Van Dorpe, is a high-throughput design with many adjacent channels.
Silicon photonics' second wave
Two concentric circles drawn in chalk are shown on-screen. So Professor Roel Baets open his plenary talk at the European Conference on Integrated Optics (ECIO) 2020, asking the online audience what is being shown.
Professor Roel Baets
Suggestions come flooding in: the cross-section of an optical fibre, a silicon wafer, a ring resonator optical component and - the correct answer - a doughnut.
The image is from the front cover of Doughnut Economics: Seven Ways to Think Like a 21st-Century Economist by Kate Raworth, a UK professor of economics.
The author discusses how continual economic growth is out of kilter with the planet’s well-being and details alternative approaches. The “doughnut” represents a sweet-spot region ensuring sustainable growth.
Baets applied the book’s thinking to his plenary talk on the topic of silicon photonics research.
Research perspective
Baets’ research work focusses on the use of silicon photonics for applications other than telecom and datacom.
High-speed transceivers for telecom and datacom continue to drive silicon photonics, creating mature platforms and funding the technology’s development.
The two industries will also continue to drive silicon photonics for the coming decade but the picture is set to change. “There is huge potential for other markets; sensing, life sciences and medical being some of them,” he says.
Baets is director of the multidisciplinary Centre for Nano- and Biophotonics at Ghent University in Belgium. His research group comprises 90 staff, split between Ghent University and imec, the renowned R&D centre. “We are sort of a hybrid unit, part university and part imec,” he says.
His focus on the next wave of silicon photonics is partly due to a long-standing interest in biomedical engineering and because high-speed transceiver research is now mainstream.
“I have a big appetite to do something less evolutionary and more groundbreaking,” he says.
Applying the technology to do something helpful appeals to him: “Diagnosing diseases or for therapy of diseases, I feel that is more relevant.”
Background
Baets received the 2020 John Tyndall Award from The Optical Society (OSA) and the IEEE Photonics Society. The award is for his “seminal research in silicon photonics and for driving the foundry model in this field.”
Baets read electrical engineering at Ghent University where he also earned a masters degree. He gained a second masters at Stanford University in California.
“It sounds redundant but I had the privilege of doing a lot of things in terms of subjects that I hadn’t been able to do at Ghent so it was wonderful,” says Baets.
It was at Stanford that Baets pursued his interest in biomedical engineering. He also ‘fell in love’ with photonics after he met and worked with Joseph Goodman, whom he describes as the father of Fourier optics and statistical optics.
That set the course of his photonics research, while his interest in biomedical engineering remained. “And it [biomedical engineering] has popped up in recent years in combination with photonics,” he says.
Foundry model
Baets compares the progress of silicon photonics with that of the chip industry several decades ago.
In the 1970s, universities undertaking integrated circuit research had clean rooms but the growing sophistication of chip-making meant it became too costly.
“Universities and research groups had to give up having their own fabrication facilities for research,” he says.
The same happened within the chip industry, with few chip firms able to afford clean rooms resulting in the advent of foundries.
Even the semiconductor titan Intel, which built its fortune by leading the chip industry in CMOS process technology, is now considering foundries to make its chips.
A similar model is now playing out with integrated photonics.
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“I believe the field of silicon photonics is at a pivotal point of change and acceleration.”
“The microelectronics fab is an extremely expensive infrastructure,” says Baets. “Maintaining the process flow for certain platforms that enable you to combine [optical] functions on-chip takes quite a bit of diligence and therefore cost.”
This is why creating ‘open’ mechanisms whereby interested parties can gain access to such technology is so important.
“Even if you don’t have a fab in your backyard, there are places you can go to,” says Baets. “That was the essence behind starting ePIXfab.”
Baets helped found ePIXfab, the first global multi-project wafer service for silicon photonics, in 2006.
The idea of multi-project wafers is to aggregate photonic designs from many different users into one mask set before passing a wafer run through a fab. “Multi-project wafers is a cost-sharing process that is well established in electronics,” he says.
Platforms
The Kate Raworth book on sustainable growth was an eye-opener to many people, says Baets, given the topic was addressed by an economist rather than a climate-change scientist.
“Growth is important but there are other dimensions, and you need to find a sweet spot,” he says. “I couldn’t resist using this for my ECIO talk as a metaphor for the field of silicon photonics.”
Silicon photonics is at a turning point, he says, and it will be interesting to see how the field develops over the next five to ten years in terms of finding a way to create mature platforms serving different applications and markets.
The term platform refers to the entire chain of processes that happen in a microelectronics fab, starting with plain wafers and ending with diced chips.
When Baets talks about mature platforms he is referring to a standardised process flow where the basic components are well defined and where a user has some freedom in how the optical functions are connected. It should also be “open access”, similar to CMOS chip foundries.
The technology used for chip-making - the wafer-level processes and the infrastructure - is hugely expensive yet what it produces - the chips - are ‘insanely cheap’, says Baets
“Because of these special boundary conditions, you have to be careful in the research directions you choose,” he says. ”It doesn’t make sense to embark in a direction where it is hard to imagine how it would fit into a sustainable platform.“
This is the essence of his plenary talk.
For example, several places around the world have created a process flow that combines silicon nitride optical waveguides with standard silicon ones. This has only happened in the last couple of years.
“It is a beautiful example of how you can extend the richness of a platform to another level, thereby serving many new applications and customers,” he says.
Meanwhile, a current focus of academic research concerns ways to add III-V lasers to the silica substrate, what he describes as the Holy Grail of silicon photonics.
Baets stresses that there is huge potential for many different applications in the coming years but that it will only happen if real-world products can be made in places that have mature, open-access platforms.
“This is not entirely trivial as it is expensive to establish such platforms,” he says.
There is also this dream of creating a unified platform that can do everything. But Baets says such a generic platform is unrealistic given the overall range of wavelengths used, for datacom, telecom and the longer wavelengths of infra-red.
“You cannot expect one platform to serve all of these,” says Baets. ”But, equally, if there is too much fragmentation, things will not turn out well,” he says.
Baets is aware of at least 20-30 start-up companies developing silicon photonics products, not for datacom or telecom.
In his plenary talk he listed such applications as neuromorphic computing, quantum computing, virtual reality – augmented reality, environmental sensing such as for gas using mid-infrared, critical infrastructure monitoring, and a variery of medical applications such as biosensors, cardiovascular monitoring, glucose monitoring neurophotonics and optical coherence tomography.
Not all these players will be successful but he does expect silicon photonics chips to be made in volumes that will eclipse telecom and datacom in the next five years or so.
But that brings us back to the issue of platforms. “Can they [designers] do things with the existing platforms or do they need a platform that goes a step further - or three steps further?” he says. “And then that question of a unified platform comes up again.”
Training
Baets is dedicating part of his time to address the issue of training in silicon photonics.
“There is a shortage of people with the skills to do silicon photonics,” he says.
Silicon foundries are full of people that understand electronics devices and there is a need for people that understand photonic devices, which are different.
People are also needed with application skills.
“If you think of medical devices, there is a vast distance between expertise in medical-device companies and expertise in the field of silicon photonics,” says Baets. “So there is a need for a lot of bridging work to make people aware of the potential of photonics in general and silicon photonics in particular.”
This is a role ePIXfab has embraced with training activities to address this need.
Research goals
What would Baets like to witness given another decade of uninterrupted research work?
“It is all about impact,” he says. “You would want to see research work turned into something that, at the end of the day, helps people.”
He has great respect for curiosity-driven research. “Curiosity-driven research is like art,” he says. “It is something that is beautiful if done by people with the right skills and is something that society can afford.”
But he is less attracted to conceptual beauty and more to things that prove helpful: “This whole field is about things that help people, whether that is the internet or a medical device.”
Meanwhile, there is COVID-19 to contend with.
As we complete the interview, Baets has a follow-on online meeting with his students.
And the previous evening he attended his first live concert since the start of the COVID-19 lockdown, given by Belgium jazz pianist, Jef Neve. “It was a privilege and it was very enjoyable,” he says.
Classical music is a passion of Baets and in his youth, he played the piano.
“The number of times I now touch the piano is limited but I have some ambition to take it up again,” he says.
Further Information:
Kim Roberts, 2019 John Tyndall Award winner, click here
Windstream to add ICE6 as it stirs its optical network
Windstream has sent an 800-gigabit optical signal between the US cities of Phoenix and San Diego. The operator used Infinera’s Groove modular chassis fitted with its latest ICE6 infinite capacity engine for the trial.
Infinera reported in March sending an 800-gigabit signal 950km with another operator but this is the first time a customer, Windstream, is openly discussing a trial and the technology.
The bulk of Windstream’s traffic is sent using 100-gigabit wavelengths. Moving to 800-gigabit will reduce its optical transport costs.
Windstream will also be able to cram more digital traffic down its fibre. It sends 12 terabits and that could grow to 40 terabits.
Motivation
Windstream provides residential broadband, business and wholesale services in the US.
“We operate a national footprint for wholesale and enterprise services,” says Art Nichols, vice president of architecture and technology at Windstream. “The optical focus is for wholesale and enterprise.”
Art Nichols
The communications service provider has 160,000 miles of fibre, 3,700 points-of-presence (PoPs) and operates in 840 cities. “We are continually looking to expand that,” says Nichols. “Picking up new PoPs, on-ramps and landing spots to jump onto the long-haul network.”
If Windstream’s traffic is predominantly at 100-gigabit, it also has 200-gigabit wavelengths and introduced recently 400-gigabit signals. In April Windstream and Infinera trialled Gigabit Ethernet (GbE) client-side services using LR8 modules.
Windstream is interested in adopting 800-gigabit wavelengths to reduce transport costs. “To try to draw as much efficiency as you can, using as few lasers as you can, to push down the cost-per-bit,” says Nichols.
The operator is experiencing traffic growth at a 20-30 per cent compound annual growth rate that is eroding its revenue-per-bit.
Weekly traffic has also jumped a further 20 per cent during the COVID-19 pandemic. Video traffic is the main driver, with peak traffic hours starting earlier in the day and continuing into the evenings.
Sending more data on a wavelength reduces cost-per-bit and improves revenue-per-bit figures.
In addition to sending a 800-gigabit signal over 730km, the operator sent a 700-gigabit signal 1,460km. The two spans are representative of Windstream’s network.
“Eight hundred gigabits is an easier multiple - better to fit two 400GbE clients - but 700 gigabits has tons of applications,” says Nichols. “We are predominantly filling 100-gigabit orders today so being able to multiplex them is advantageous.”
Another reason to embrace the new technology is to fulfill wholesale orders in days not months. “The ability to turn around multi-terabit orders from webscale customers,” says Nichols. “That is increasingly expected of us.”
One reason order fulfilment is faster is that the programming interfaces of the equipment are exposed, allowing Windstream to connect its management software. “We instantiate services in a short turnaround,” says Nichols.
ICE6 technology
Infinera’s ICE6 uses a 1.6-terabit photonics integrated circuit (PIC) and its 7nm CMOS FlexCoherent 6 digital signal processor (DSP). The 1.6 terabits is achieved using two wavelengths, each able to carry up to 800 gigabits of traffic.
The ICE6 uses several techniques to achieve its optical performance. One is Nyquist sub-carriers where data is encoded onto several sub-carriers rather than modulating all the data onto a single carrier.
The benefit of sub-carriers is that high data rates are achieved despite the symbol rate of each sub-carrier being much lower. The lower symbol rate means the optical transmission is more tolerant to non-linear channel impairments. Sub-carriers also have sharper edges so can be squeezed together enabling more data in a given slice of spectrum.
Infinera also applies probabilistic constellation shaping to each sub-carrier, enabling just the right amount of data to be placed on each one.
The FlexCoherent 6 DSP also uses soft-decision forward-error correction (SD-FEC) gain sharing. The chip can redistribute processing to the optical channel that needs it the most.
Some of the strength of the stronger signal can be cashed in to strengthen the weaker one, extending its reach or potentially allowing more bits to be sent by enabling a higher modulation scheme to be used.
Windstream cannot quantify the cost-per-bit advantage using the ICE6. “We don’t have finalised pricing,” says Nichols. But he says the latest coherent technology has significantly better spectral efficiency.
Spectral efficiency can be increased in two ways, says Rob Shore, Infinera’s senior vice president of marketing.
One is to increase the modulation scheme and the other is to close the link and maintain the high modulation over longer spans. If the link can’t be closed, lowering the modulation scheme is required which reduces the bits carried and the spectral efficiency.
Windstream will be able to increase capacity per fibre by as much as 70 per cent compared to the earlier generation 400-gigabit coherent technology and by as much as 35 per cent compared to 600-gigabit coherent.
A total of 42.4 terabits can be sent over a fibre using 800-gigabit wavelengths, says Shore, but the symbol rate needs to be reduced to 84 gigabaud shortening the overall reach.
Trial learnings
The rate-reach performance of the ICE6 was central to the trial but what Windstream sought to answer was how the ICE6 would perform across its network.
“We paid really close attention to margins and noise isolation as indicators as to how it would work across the network,” says Nichols. “The exciting thing is that it is extremely applicable.”
Windstream is also upbeat about the technology’s optical performance.
“We have a fair amount of information as to what the latest optical engines are capable of,” says Nichols. “This trial gave us a good view of how the ICE6 performs and it turns out it has advantages in terms of rate-reach performance.”
Ciena, Huawei and Infinera all have 800-gigabit coherent technology. Nokia recently unveiled its PSE-V family of coherent devices that does not implement 800-gigabit wavelengths.
Michael Genovese, a financial analyst at MKM Partners, puts the ICE6 on a par with Ciena’s WaveLogic 5 that is already shipping to over 12 customers.
“We expect 800 gigabit to be a large and long cycle," says Genovese in a recent research note. “We think most of the important internet content providers, telcos and subsea consortia will adopt a duel-vendor strategy, benefitting Ciena and Infinera over time.”
Windstream will adopt Infinera’s ICE6 technology in the first half of 2021. First customers to adopt the ICE6 will be the internet content providers later this year.
Optical supply chain set to withstand the COVID-19 crisis
The optical supply chain will not experience any lasting damage as a result of the COVID-19 pandemic. So argues LightCounting in a research note.
The market research company notes how the experience of the Coronavirus pandemic has highlighted the many benefits of the digital economy.
And the jolt the world is experiencing will if anything, strengthen it.
“All kind of things are happening as a result of the pandemic,” says John Lively, principal analyst at LightCounting and author of the research note. “Telecommuting, telelearning and telemedicine have all been used before, but never on a scale like this.”
Pandemic toll
Given how governments have shut down activities to contain the spread of the virus, it comes as no surprise the severity with which the world’s economy has been hit during the first quarter of 2020.
LightCounting cites startling figures concerning the world’s two largest economies.
Some 6.6 million Americans filed unemployment claims in the week ending April 1st, double the previous record that was set just a week earlier. And up to 47 million jobs could be lost, a third of the total US workforce, according to the US Federal Reserve Bank.
Meanwhile, in China, the gross domestic product (GDP) in the first quarter is expected to plummet 9 per cent, the first decline in three decades.
Looking more closely at the telecom and datacom industries, LightCounting highlights four developments that overall give cause for optimism.
Returning to work
First, China is returning to work. LightCounting cites figures from China that claim that factories are now staffed at 80-90 per cent of their full production levels. However, figures published by the American Chamber of Commerce in China are less rosy. Of the 120 member companies it surveyed, a quarter said all their staff continued to work from home (as of March 13th).
Talking to Chinese optical component companies, LightCounting says each firm has gone through a process with their local governments to reopen such as meeting the various hygiene protocols and ensuring a suitable distance between staff.
The second development is notable growth in network traffic as a result of people working from home and families being in lockdown.
The growth in the use of the videoconferencing tool, Zoom, is well documented, but strong growth has been witnessed elsewhere. Microsoft’s Teams collaboration application reached 44 million daily users, up 12 million in a week, while the use of its Windows Virtual Desktop has tripled.
In turn, AT&T and Verizon have reported double-digit growth in viewers of their TV and streaming demand content, while Netflix, YouTube and Disney have cut by a quarter their streaming video quality in Europe to lessen the network burden.
Spending on infrastructure by the operators, the third pointer highlighted by LightCounting, promises encouraging growth. The main three Chinese operators plan to increase their 5G spending in 2020. China Mobile, for example, is spending 100 billion yuan on 5G infrastructure, 4x what it spent on 5G in 2019.
Lastly, telecom equipment and component sales are expected to be down in the first quarter, with five companies – Ciena, Infinera, Lumentum, II-VI and NeoPhotonics – issuing guidance warnings.
These range from Ciena which lowered its previous guidance by 3 per cent to NeoPhotonics which expects a 10 per cent drop in the first quarter.
The responses of Chinese optical component players range from not expecting sales to be hit at all to a 15 per cent decline in 2020. LightCounting also noted that companies with sales predominantly outside China were more worried about demand in the coming two quarters.
Punctuated Equilibrium
LightCounting cites a concept coined by Stephen J. Gould, the late evolutionary biologist, of punctuated equilibrium which argues that species do not evolve at a constant rate. Rather, they experience long periods of stability followed by rapid bursts of change due to significant disturbances in their environment.
“The same applies to societies and economies,” says Lively.
This explains why LightCounting believes the coronavirus of 2020-21 will accelerate trends that promote the digital economy.
Lively cites the tens of millions of US students and adult workers now operating from home. “Once the genie is out of the bottle it may prove difficult to put back,” says Lively who, as an analyst, has worked from home for over two decades.
In turn, the need for social hygiene and new habits such as touch-free shopping will boost adoption of digital wallet technology.
Current events also highlight the importance of broadband and the disparity in the quality of service being delivered, especially in rural areas. This too will cause change.
The hyperscalers – Alphabet (Google), Amazon, Apple, Facebook and Microsoft – are well-positioned to weather the storm, being providers of the hubs of the digital economy and having deep pockets. Malls and other brick-and-mortar retailers, in contrast, will suffer greatly.
Lively stresses that it is early days and that the analysis is speculative. It also assumes that massive damage won’t be done to huge swathes of the global economy.
But he is confident that the optical industry will not be badly damaged, and nowhere near the scale of the bursting of the dotcom bubble in 2000 that then crashed the optical industry.
“The oversupply of bandwidth [which developed during the dotcom boom] resulted in a drastic cutback in demand, and that hit our industry directly,” he says. Revenues shrank 30 per cent in 2001 and 30 per cent again in 2002.
“It took years to recover and many companies went out of business including hundreds of start-ups,” says Lively. “But the big players remain, even if some have changed their names.”
Current events will not be as severe as two decades ago since the epic oversupply of bandwidth directly impacted the optical industry, says Lively.
He also ends on a positive note: “It is difficult to think of another industry we would rather be in as we ride this storm.”