OFC 2023 show preview
- Sunday, March 5 marks the start of the Optical Fiber Communication (OFC) conference in San Diego, California
- The three General Chairs – Ramon Casellas, Chris Cole, and Ming-Jun Li – discuss the upcoming conference
OFC 2023 will be a show of multiple themes. That, at least, is the view of the team overseeing and coordinating this year’s conference and exhibition.
General Chair Ming-Jun Li of Corning who is also the recipient of the 2023 John Tyndall Award (see profiles, bottom), begins by highlighting the 1,000 paper submissions, suggesting that OFC has returned to pre-pandemic levels.
Ramon Casellas, another General Chair, highlights this year’s emphasis on the social aspects of technology. “We are trying not to forget what we are doing and why we are doing it,” he says.
Casellas highlights the OFC’s Plenary Session speakers (see section, below), an invited talk by Professor Dimitra Simeonidou of the University of Bristol, entitled: Human-Centric Networking and the Road to 6G, and a special event on sustainability.
This year’s OFC has received more submissions on quantum communications totaling 66 papers.
In the past, papers on quantum communications were submitted across OFC’s tracks addressing networking, subsystems and systems, and devices. However, evaluating them was challenging given that only some reviewers are quantum experts, says Chris Cole, the third General Chair. Now, OFC has a subcommittee dedicated to quantum.
Another first is OFCnet, a production network that will run during the show.
Themes and topics
Machine learning is one notable topic this year. The subject is familiar at OFC, says Casellas, but people are discussing it more.
Casellas highlights one session at OFC 2021 that addressed machine learning for optics and optics for machine learning. “It showed the duality of how you can use photonic components to do machine learning and apply machine learning to optimise networking,” says Casellas.
This year there will be additional aspects of machine learning for networks, transmission, and operations, says Casellas.
Other General Chair highlighted subjects include point-to-multipoint coherent transmission, non-terrestrial and satellite networks, and optical switching and how its benefits networking in the data centre.
Google, for example, is presenting a paper detailing its use of optical switching in its data centres, something the hyperscaler disclosed at the ACM Sigcomm conference in August 2022.
There is also more interest in fibre sensors used in communications networks.
“We see an increasing trend because now if you want smart networks, you need sensors everywhere,” says Li.
“That is another theme that goes across all the tracks, which is a non-traditional optical fibre communication area that we’ve been embracing,” adds Cole.
As examples, Cole cites lidar, radio over fibre, free-space communications, microwave fibre sensing, and optical processing.
OFC has had contributions in these areas, he says, but now these topics have dedicated subcommittee titles.
Plenary session
This year’s three Plenary Session speakers are:
- Patricia Obo-Nai, CEO of Vodafone Ghana, who will discuss Harnessing Digitalization for Effective Social Change,
- Jayshree V. Ullal, president and CEO of Arista Networks, addressing The Road to Petascale Cloud Networking,
- and Wendell P. Weeks, chairman and CEO of Corning, whose talk is entitled Capacity to Transform.
“We thought that having someone who could explain how technology improves society would be very positive,” says Casellas. “I’m proud to have someone who can talk on the benefits of digitisation from the point of view of society, in addition to more technical topics.”
Li highlights how OFC celebrated the 50th anniversary of low-loss fibre two years ago and that last year, OFC celebrated the year of glass, displaying information on panels.
Corning has played an important role in both technologies. “Having a speaker [Wendell Weeks] from a glass company talking about both will be interesting to the OFC audience,” says Li.
Cole highlights the third speaker, Jayshree Ullal, the CEO of Arista. The successful networking player is one of the companies competing in what he describes as a very tough field.
Rump session
This year’s Rump Session tackles silicon photonics, a session moderated by Daniel Kuchta of IBM TJ Watson Research Center and Michael Hochberg of Luminous Computing.
Cole says silicon photonics has received tremendous attention, and the Rump Session is asking some tough questions: “Is silicon photonics for real now? Is it just one of the guys in the toolbox? Or is it being sunsetted or supplemented?”
Cole expects a lively session, not just challenging conventional thinking but having people representing exciting alternatives which are commercially successful alongside silicon photonics.
Show interests
The Chairs also highlight their interests and what they hope to learn from the show.
For Li, it is high-density fibre and cable trends.
Work on space division multiplexing (SDM) – multicore and multimode – fibre has been an OFC topic for over 15 years. One question Li has is whether systems will use SDM.
“It looks like multicore fibre is close, but we want to learn more from customers,” says Li.
Another interest is an alternative development of reduced coating diameter fibres that promise greater cable density. “I always think this is probably the short-term solution, but we’ll see what people think,” says Li.
AI drives interest in fibre density and latency issues in the data centre. Low latency is attracting interest in hollow-core fibre. Microsoft acquired Lumenisity, a UK hollow core fibre specialist, late last year.
Li is keen to learn more about quantum communications. “We want to understand, from a fibre component point of view, what to do in this area.”
Until now industry focus has been on quantum key distribution (QKD), but Li wants to learn about other applications of quantum in telecoms.
The bandwidth challenge facing datacom is Cole’s interest.
As the Rump Session shows, there has been an explosion of technologies to address data challenges, particularly in the data centre. “So I’m looking forward to continuing to see all the great ideas and all the different directions,” says Cole.
Another show interest for Cole is start-ups in components, subsystems and systems, and networking.
At Optica’s Executive Forum, held on Monday, March 6, a session is dedicated to start-ups. Casellas is looking forward to the talks on optical network automation.
Much work has applied machine learning to optical transmission and amplifier optimisation. Casellas wants to see how reinforcement learning is applied to optical network controllers. Telemetry and its use for network monitoring are another of his interests.
“Maybe because I’m an academic and idealistic, but I like everything related to disaggregation and the opening of interfaces,” says Casellas, who too wants to learn more about quantum.
“I have a basic understanding of this, but maybe it is hard to get into something new,” says Casellas. Non-terrestrial and satellite networks are other topics of interest.
Cole concludes with a big-picture view of photonics.
“It’s a great time to be in optics,” he says. “We’re seeing an explosion of creativity in different areas to solve problems.”
Ramon Casellas works at the Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) research institution in Barcelona, Spain. His research focuses on networks – particularly the control plane, operations and management – rather than optical systems and devices.
Ming-Jun Li is a Corporate Fellow at Corning where he has that worked for 32 years.
Li is also this year’s winner of the John Tyndall Award, presented by Optica and the IEEE Photonics Society. The award is for Li’s ‘seminal contributions to advances in optical fibre technology.’
“It was a surprise to me and a great honour,” says Li. “The work is not only for myself but for many people working with me at Corning; I cannot achieve without working with meaningful colleagues.”
Chris Cole is a consultant whose background is in datacom optics. He will be representing the company, Coherent, at OFC.
BT’s first quantum key distribution network
The trial of a commercial quantum-secured metro network has started in London.
The BT network enables customers to send data securely between sites by first sending encryption keys over optical fibre using a technique known as quantum key distribution (QKD).
The attraction of QKD is that any attempt to eavesdrop and intercept the keys being sent is discernable at the receiver.
The network uses QKD equipment and key management software from Toshiba while the trial also involves EY, the professional services company.
EY is using BT’s network to connect two of its London sites and will showcase the merits of QKD to its customers.
London’s quantum network
BT has been trialling QKD for data security for several years. It had announced a QKD trial in Bristol in the U.K. that uses a point-to-point system linking two businesses.
BT and Toshiba announced last October that they were expanding their QKD work to create a metro network. This is the London network that is now being trialled with customers.
Building a quantum-secure network is a different proposition from creating point-to-point links.
“You can’t build a network with millions of separate point-to-point links,” says Professor Andrew Lord, BT’s head of optical network research. “At some point, you have to do some network efficiency otherwise you just can’t afford to build it.”
BT says quantum security may start with bespoke point-to-point links required by early customers but to scale a secure quantum network, a common pipe is needed to carry all of the traffic for customers using the service. BT’s commercial quantum network, which it claims is a world-first, does just that.
“We’ve got nodes in London, three of them, and we will have quantum services coming into them from different directions,” says Lord.
Not only do the physical resources need to be shared but there are management issues regarding the keys. “How does the key management share out those resources to where they’re needed; potentially even dynamically?” says Lord.
He describes the London metro network as QKD nodes with links between them.
One node connects Canary Wharf, London‘s financial district. Another node is in the centre of London for mainstream businesses while the third node is in Slough to serve the data centre community.
“We’re looking at everything really,” says Lord. “But we’d love to engage the data centre side, the financial side – those two are really interesting to us.”
Customers’ requirements will also differ; one might want a quantum-protected Ethernet service while another may only want the network to provide them with keys.
“We have a kind of heterogeneous network that we’re starting to build here, where each customer is likely to be slightly different,” says Lord.
QKD and post-quantum algorithms
QKD uses physics principles to secure data but cryptographic techniques also being developed are based on clever maths to make data secure, even against powerful future quantum computers.
Such quantum-resistant public-key cryptographic techniques are being evaluated and standardised by the US National Institute of Standards and Technology (NIST).
BT says it plans to also use such quantum-resistant techniques and are part of its security roadmap.
“We need to look at both the NIST algorithms and the key QKD ones,” says Lord. “Both need to be developed and to be understood in a commercial environment.“
Lord points out that the encryption products that will come out of the NIST work are not yet available. BT also has plenty of fibre, he says, which can be used not just for data transmission but also for security.
He also points out that the maths-based techniques will likely become available as freeware. “You could, if you have the skills, implement them yourself completely freely,” says Lord. “So the guys that make crypto kits using these maths techniques, how do they make money?”
Also, can a user be sure that those protocols are secure? “How do you know that there isn’t a backdoor into those algorithms?” says Lord. “There’s always this niggling doubt.”
BT says the post-quantum techniques are valuable and their use does not preclude using QKD.
Satellite QKD
Satellites can also be used for QKD.
Indeed, BT has an agreement with UK start-up Arqit which is developing satellite QKD technology whereby BT has exclusive rights to distribute and market quantum keys in the UK and to UK multinationals.
BT says satellite and fibre will both play a role, the question is how much of each will be used.
“They work well together but the fibre is not going to go across oceans, it’s going to be very difficult to do that,” says Lord. “And satellite does that very well.”
However, satellite QKD will struggle to provide dense coverage.
“If you think of a low earth orbit satellite coming overhead, it’s only gonna be able to lock onto to one ground station at a time, and then it’s gone somewhere else around the world,” says Lord. More satellites can be added but that is expensive.
He expects that a small number of satellite-based ground stations will be used to pick up keys at strategic points. Regional key distribution will then be used, based on fibre, with a reach of up to 100km.
“You can see a way in which satellite the fibre solutions come together,” says Lord, the exact balance being determined by economics.
Hollow-core fibre
BT says hollow-core fibre is also attractive for QKD since the hollowness of the optical fibre’s core avoids unwanted interaction between data transmissions and the QKD.
With hollow-core, light carrying regular data doesn’t interact with the quantum light operating at a different wavelength whereas it does for standard fibre that has a solid glass core.
“The glass itself is a mechanism that gets any photons talking to each other and that’s not good,” says Lord. “Particularly, it causes Raman scattering, a nonlinear process in glass, where light, if it’s got enough power, creates a lot of different wavelengths.”
In experiments using standard fibre carrying classical and quantum data, BT has had to turn down the power of the data signal to avoid the Raman effect and ensure the quantum path works.
Classical data generate noise photons that get into the quantum channel and that can’t be avoided. Moreover, filtering doesn’t work because the photons can’t be distinguished. It means the resulting noise stops the QKD system from working.
In contrast, with hollow-core fibre, there is no Raman effect and the classical data signal’s power can be ramped to normal transmission levels.
Another often-cited benefit of hollow-core fibre is its low latency performance. But for QKD that is not an issue: the keys are distributed first and the encryption may happen seconds or even minutes later.
But hollow-core fibre doesn’t just offer low latency, it offers tightly-controlled latency. With standard fibre the latency ‘wiggles around’ a lot due to the temperature of the fibre and pressure. But with a hollow core, such jitter is 20x less and this can be exploited when sending photons.
“As time goes on with the building of quantum networks, timing is going to become increasingly important because you want to know when your photons are due to arrive,” says Lord.
If a photon is expected, the detector can be opened just before its arrival. Detectors are sensitive and the longer they are open, the more likely they are to take in unwanted light.
“Once they’ve taken something in that’s rubbish, you have to reset them and start again,” he says. “And you have to tidy it all up before you can get ready for the next one. This is how these things work.“
The longer that detector can be kept closed, the better it performs when it is opened. It also means a higher key rate becomes possible.
“Ultimately, you’re going to need much better synchronisation and much better predictability in the fibre,” says Lord. “That’s another reason why I like hollow-core fibre for QKD.”
Quantum networks
“People focussed on just trying to build a QKD service, miss the point; that’s not going to be enough in itself,” says Lord. “This is a much longer journey towards building quantum networks.”
BT sees building quantum small-scale QKD networks as the first step towards something much bigger. And it is not just BT. There is the Innovate UK programme in the UK. There are also key European, US and China initiatives.
“All of these big nation-states and continents are heading towards a kind of Stage I, building a QKD link or a QKD network but that will take them to bigger things such as building a quantum network where you are now distributing quantum things.”
This will also include connecting quantum computers.
Lord says different types of quantum computers are emerging and no one yet knows which one is going to win. He believes all will be employed for different kinds of use cases.
“In the future, there will be a broad range of geographically scattered quantum computing resources, as well as classical compute resources,” says Lord. “That is a future internet.”
To connect such quantum computers, quantum information will need to be exchanged between them.
Lord says BT is working with quantum computing experts in the UK to determine what the capabilities of quantum computers are and what they are good at solving. It is classifying quantum computing capabilities into the different categories and matching them with problems BT has.
“In some cases, there’s a good match, in some cases, there isn’t,” says Lord. “So we try to extrapolate from that to say, well, what would our customers want to do with these and it’s a work in progress.”
Lord says it is still early days concerning quantum computing. But he expects quantum resources to sit alongside classical computing with quantum computers being used as required.
“Customers probably won’t use it for very long; maybe buying a few seconds on a quantum computer might be enough for them to run the algorithm that they need,” he says. In effect, quantum computing will eventually be another accelerator alongside classical computing.
”You already can buy time by the second on things like D-Wave Systems’ quantum computers, and you may think, well, how is that useful?” says Lord. “But you can do an awful lot in that time on a quantum computer.”
Lord already spends a third of his working week on quantum.
“It’s such a big growing subject, we need to invest time in it,” says Lord.
