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Connecting with OFC 2018

Tuesday, April 17, 2018 | by Rudy Montgelas



Connecting with OFC 2018

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You probably remember, from a CTD that I did last year, that “The OFC (Optical Fiber Communications) conference is the largest fiber optics and optical communications technical conference in the world, drawing many of the top optical scientists, companies and experts in the field of optics and optical communications”.1 OFC is co-sponsored by the IEEE communications Society, the IEEE Photonics Society and the Optical Society of America (OSA) every year. The San Diego Convention Center housed over 15,500 attendees, with more than 850 peer reviewed technical sessions presented at the conference this year.  And, in addition to the technical sessions, there was a large trade show floor with over 700 exhibitors showing the latest developments in transceivers, fiber cables, connectors and other communications products for hyperscale data centers, outside plant, cellular systems, R&D laboratories and optical component manufacturing.

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While out in San Diego this March for OFC 2018, I was fortunate enough to avoid the third Nor’easter, that had hit the coast.  I was just in time to see and hear about the latest developments in fiber and laser optical communications at OFC.  It amazes me to see the advancements and technical achievements that can emerge from this industry in just one year.

The Plenary:

OFC starts off the week with speakers from key companies and educational institutions performing groundbreaking research in optical communications, and their top award, the John Tyndall award, is presented each year to a significant contributor to the optics field.
This year’s plenary featured an enlightening talk by Marcus Weldon, President of Nokia Bell Labs, USA on “The future of deterministic dynamic networking (and the new value equation).”2 He also indicated that the current wireless network has just about exhausted available spectrum and that there is a “rise of small cells” to promote connectivity”.  Also, when regarding the desire to obtain low network latency over longer and longer distances, we need to consider the speed of light network limitations at 100km distances with 100ms latencies.2

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Martin Birk, from AT&T Labs, presented Peter Winzer with the Tyndall award this year for his research work at Nokia Bell Labs in the field of coherent optical communications for networks.  Coherent detection is emerging as a contending solution to direct detection for high speed optical networks in data centers as well as long haul networks, as I’ll describe a bit later in the CTD.

Chengliang Zhang presented his views on how China Telcom’s next generation directions for wireless and how high speed/low latency optical telecommunication networks fit in China’s fast growing communications marketplace.3

The session wrapped up with professor John Doyle describing his research in applying knowledge of biological neural processes and human brain functions to describing how those concepts apply for deriving mathematical “universal laws and architectures” for communications networks in terms of speeds, scalability and performance.4

Coherent versus Direct Detect Detection

A big discussion, at OFC 2018, was the cost effectiveness of using what’s known as coherent communications, versus the traditional direct optical, or “Direct Detect” method of communication.  What? Radio over Fiber? – “Come in, Berlin?” … --- … ! That’s right folks!  The electromagnetic spectrum of light can support huge amounts of transmitted information through its phase, amplitude and polarization.  By “tuning” a local oscillator laser’s phase, amplitude and polarization, at the receiver, to the received signal itself, large amounts of high bandwidth information can be transmitted and detected through a coherent optical link.  What this means is that transceivers could take a rapid turn toward coherent photonic integrated circuits as bandwidth increases, because more and more optical and electronic signal processing can be integrated into the chip itself.

As communications systems become more complex, and, in order to support 400Gbps into terabit speeds, digital signal processing, forward error correction (FEC) and other advanced communication technologies, such as pulsed amplitude modulation (PAM) and quadrature amplitude modulation (QAM), are being applied to sophisticated communications hardware with wavelength division multiplexing (WDM) and coherent communications, to offer cost effective solutions for high speed/low latency communication channels.5 The need for more speed is going to keep growing as more and more IoT gizmos, hungry for data processing from the core, are added to the networkEdge. In fact, the data center switches themselves are migrating to higher and higher I/O capabilities:

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The 400 Giggle”

The large IT services companies, that need high-performing data center capability, such as Google, Facebook and Microsoft are looking to the low cost and power, high performance, 400 Gigabit fiber optic connection component manufacturers for better and better products.  The “humor” at the conference between these service companies and the transceiver device manufacturers, such as Finisar and Intel, seemed to be: “Twice the performance at half the cost”. In other words, the target for the next generation 400 Gbs transceivers is for the device manufacturers to make them available at half the cost with twice the transmission capability, and, with lower power consumption as well.Those are some of the reasons why the COBO was formed.6

COBO and Silicon Photonic Integrated Circuits (PICs)

The consortium for on-board optics, or COBO, was formed from a group of companies interested in developing optimized packaging and cooling solutions for the optics.6 This includes not only the transceiver optical and electrical connectors, but also the device packaging, so that photonic integrated chips (PICs) with optimized cooling heat sinks can be utilized to reduce device power consumption and improve signal integrity. A 2.4 Tbps experimental PIC module presented at the conference, is a good example of this, where 4 x 600 Gbps optical circuits are created on a single chip.   The large hyperscales also discussed the use of optimized heatsink packaging at the front of the transceiver modules and optimized electrical power and signal connectors within the device packaging.

Software defined networking (SDN), NVF and AI

Software defined networking (SDN) and Network Function Virtualization (NVF) are developing approaches to adding software control and monitoring for both short and long-haul network connections, especially as they become more complex and difficult to manage.  Network function virtualization uses the technologies of IT virtualization to virtualize entire classes of network node functions into building blocks that may connect or be chained together to create communication services.   Rather than requiring custom hardware devices for each network function, NFV operates with Virtualized Network Functions, or VNFs, on virtual machines that run different software modules and processes. This is done on top of the standard high-volume servers, switches, storage devices, and the cloud computing infrastructure within the data center.

A “disaggregated and fully open” networking solution, was one of the key drivers behind Facebook’s Open Compute Systems (OCP) project.  In addition, Facebook feels that artificial intelligence (AI) and Machine Learning (ML), combined with neural network (ONNX- Open Neural Net Exchange), and network telemetry, are going to be the best approach for their predictive network failure and network integrity requirements.

PoN and PoL

Passive Optical Network (PoN) and Passive Optical LAN (PoL) systems are being used to bring high speed low latency communications to subscribers and end users. PoNs and PoLs employ bi-directional communications over single mode fibers for cost effective subscriber service connections, from the OLT at the core, to the ONT at the subscriber.  The demand for single mode PLC optical splitter devices, a key PoN/PoL component, is significantly increasing according to a recent report.Next generation passive optical networks and LANs are gaining interest for building network subscriber drops.  In addition, the need for higher bandwidths over longer distance singlemode fiber connections is also increasing, which is why many of the cellular companies are looking at beefing-up both their front-haul, as well as their back-haul networks with PoN-based systems (See the chart below):8

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WI-Fi, Li-Fi and Visible Light Communications (VLC)

Cellular companies, such as Verizon and China Telecom, are looking at future solutions for the wireless networks, with 100 and 400Gig connections out to “small cells” that support local metro subscriber connections to mobile cellular devices and the 5G network. They are also looking toward higher speed singlemode PoN systems (From 10Gbps, even out to 200Gbps) over very long distances (20km to 650km) for connecting the upcoming 5G network to an ever-increasing number of subscribers with accelerating IoT mobile device demands.

Li-Fi communication uses the infrared optical spectrum to provide a full duplex connection between remote devices and Li-Fi wireless transceiver access points in the ceiling or around a room.  Sometimes these systems might also use the overhead visible LED lights themselves (VLC) as the data transceivers for line-of-sight, two-way optical data transmission.

Fraunhofer presented some of their research work in Germany with BMW on a multiple receiver light-based Li-Fi communications system combined with a robotic arm at a BMW assembly plant. 

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Fraunhofer also demonstrated an infrared LED based office communications system using multiple light path detectors and sources to assure uninterrupted PC video communication in an office environment at high data rates, as well as developing a multi-user Li-Fi office device.Basic Li-Fi systems are line of sight. However, by placing multiple receivers in the office area, Fraunhofer showed how they could avoid signal interruption from light blockages in their optical system.  They indicated that they could get up to 800Mbps for small spot sizes but reported challenges with larger coverage at higher data rates.  A group from Italy also presented a Li-Fi experiment employing a 200 Mbps optical system with no lens for a 1m2  radius “hot spot”, and they also guaranteed that they could achieve a 100 Mbps link over a 3m2 radius10

Robotics at the cross-connect

Robotics and data center interconnectivity has been combined, using robotic cross-connect “switches” to mechanically make physical connections inside a cabinet.  A robotic arm picks, cleans, routes and plugs in the mated pair patch cord connections from 1.6mm LC patch cords located inside a high-density cross-connect panel.  Telescent, Calient and East Point Communication Technology were some of the companies that had robotic LC duplex fiber connector systems on the OFC show floor, as well as others that employed different optical path switching technologies such as MEMs micro mirror elements.

The End….

If you’ve read through all this, you’re probably worn out from all the alphabet soup and technical gibberish I’ve thrown at you.  But, I hope that some of this has been helpful and might possible spark some further interest.
Until next time, I look forward to sharing another CTD with you.

References and further reading:

1 Connecting the Dots, “Connecting with OFC 2017” R. Montgelas 4-5-2017
2 “The future of deterministic dynamic networking (and the new value equation).”, Marcus Weldon, OFC 2018 Plenary Session, March 11, 2018
3 “Chengliang Zhang,””, OFC 2018 Plenary Session, March 11, 2018
4 John C. Doyle””, OFC 2018 Plenary Session, March 11, 2018
5 Connecting the Dots (CTD), “Boosting Fiber Optic links” R. Montgelas 4-27-2016
6 COBO website url: http://onboardoptics.org/
7 “Global PLC splitter consumption reaches nearly 33 million units: ElectroniCast”, March 29, 2018
8 Source: Ovum, TMT Intelligence, Copyright Informa PLC
9 “Use cases for Optical Wireless Communications”, D. Schulz, Fraunhofer, OFC 2018
10 “230 Mbp/s Real-time Optical Wireless Transmission in Non-Directed Line-of Sight Configuration”, G.Cossu, A. Messa, W. Ali, A. Sturniolo, Scuola Superiore Sant’Anna, Pizza, Italy