OFC 2018 focuses on higher-speed optical networks

15 Mar 2018

Week-long communications expo relocates to San Diego, expecting more than 15,000 attendees.

Relocated this year from 2017's Los Angeles to the San Diego Convention Center, OFC 2018 (the Optical Fiber Communications Conference) is this week giving attendees the opportunity to explore the latest in optical communications innovation, data-center connectivity, 5G network upgrades and cloud computing technology.

This year’s conference and exhibition features more than 15,000 attendees, 700-plus exhibiting companies (including Cisco, Coherent, Coriant, Emcore, Lumentum and more), plenary speakers aplenty, and innumerable invited speakers, tutorials, panels and short courses focused on optical technologies.

The OFC 2018 Media Center features many conference product releases and technical and exhibitor announcements.

Speakers are offering different perspectives on current hot topics around the optical communications field, including:

• John C. Doyle, Jean-Lou Chameau Professor of Control and Dynamical Systems, Electrical Engineer, and BioEngineering, California Institute of Technology (Caltech) delivering an address on “Universal Laws and Architectures in Complex Networks.”
• Marcus Weldon, President, Nokia Bell Labs will give a talk on “The Future of Dynamic Deterministic Networking”; and
• Chengliang Zhang, Vice President, China Telecom Beijing Research Institute, will give a plenary talk on “Optical Networking in the Cloud and 5G Era” — Zhang’s talk will present the recent optical network evolution of China Telecom and other major Chinese network operators.

Study compares 400G optical transceivers in data centres

Also being presented at this year’s OFC conference is the work by an international research team from Greece, Luxemburg and Spain, who have analyzed the cost and power usage of different 400G transceivers. The results include predictions of each transceiver’s likely cost reduction trend over the next five years, using a mathematical model.

"The 400G-transceiver market is one of the fastest evolving markets, and our study showed 400G transceivers provide more significant benefits compared to current generation transceivers in terms of cost and power consumption,” said Theodoros Rokkas, primary author of the paper and a scientist working at Athens Information Technology, Greece, in the framework of EU R&D project DIMENSION, and inCITES Consulting.

“We believe our analysis and evaluation can provide some insights and guidelines for device manufacturers and users regarding the best choice of 400G transceivers and the optimal transceiver-installation approach that can be applied in different Data Centers. Next-generation optical transceivers such as 400G, 800G or even 1.6T interconnects promise to use less power and be less expensive, smarter and smaller.”

Cost-benefit analysis

To estimate the total cost of 400G devices, Rokkas and his colleagues broke the cost into three discrete parts: the cost of manufacturing the Photonic Engine — a system that uses photonic devices as the main component of an optical transceiver; the cost of purchasing the electronics, including digital signal processing chips; and the cost for the optical and mechanical packaging of the transceiver module.

They calculated the relative cost of several 400G transceivers based on the cost of a reference 100G transceiver. The total area of the chip, size of the wafer, number of devices, number of optical coupling connections and total achieved yield determined the difference in cost.

Similarly, to calculate the total power consumption of each of the transceivers, the researchers considered the power consumption of the three discrete parts separately. They also predicted the price evolution over the next five years using the extended learning curve model, a widely used mathematical function that estimates the future price of components used in telecommunication networks. According to Rokkas, the trend over time in device cost reduction is primarily due to technology maturity, and is predicted for the first time.

Rokkas concluded, “The five types of 400G transceivers we studied are all possible standard options that were examined by the IEEE P802.3bs technical group. The analysis revealed that 400G transceivers with a lower number of laser sources and higher Baud rate, i.e. data transmission rate, are superior than other transceiver types in terms of scaling, cost and power consumption. We expect this advantage to be more prevalent in the case of next generation transceivers (800G or 1.6T).”

High capacity fiber transmission

A new type of off-line signal transmission mechanism, experimentally demonstrated just a few years ago, has come on-line as a real-time bidirectional transmission system. At this week's OFC, a research team from Nokia is presenting the bi-directional transmission of 78 interleaved, 400 gigabit per second channels with a 31.2 terabit per second fiber capacity.

At twice the 200 Gb/s standard rate found in most applications, the C-band signals are transmitted over a single, 90-kilometer-long single-mode fiber. The developers say that such a high transmission capacity and rate “would offer a particularly attractive capacity bump to current data center interconnections, where nearby data centers are coupled together to form a single, larger center.”

“So far, three different companies have demonstrated a real-time 400 Gb/s transponder over the last three years, but we are the only ones reporting 400 Gb/s with such high spectral efficiency,” said Thierry Zami, who is presenting the team’s work. “The spectral efficiency allows us to provide quite a large fiber capacity. So, in this case we claim 31.2 Tb/s, but in practice, without the limitations in terms of number of loading channels in our lab, we could have reached about 38 Tb/s over whole C band. This is really one of the innovative points.”