ANTONY SAVVAS REDESIGNING LASERS
The Chalmers researchers have now succeeded in designing these chips with optimised circuits. Per Larsson-Edefors, professor in computer engineering at the Department of Computer Science and Engineering at Chalmers, said, “Our measurements show that the energy consumption of our refined chips is around ten times less than conventional error-correcting chips.” Among the new designs, the researchers have also demonstrated the advantages of using “optical frequency combs” instead of having separate laser transmitters for each frequency channel. An optical frequency comb emits light at all wavelengths simultaneously, making the transmitter “very frequency-stable”. This makes reception of the signals much easier, and thus more energy efficient. Energy savings can also be made through controlling fibre optic communications at the network level. By mathematically modelling the energy consumption in different network resources, data traffic can be controlled and directed so that the resources are “utilised optimally”. This is especially valuable if traffic varies over time, as is the case in most networks. For this, the researchers developed an optimisation algorithm which can reduce network energy consumption “by up to 70%”. Chalmers says the new technologies do not come with any performance sacrifice, “potentially making the internet of the future considerably more energy-efficient”. 5G The gradual roll-out of 5G mobile networks is encouraging wide-scale testing in the optical networking field, with Nokia Bell Lab’s work just one example. Its researchers set a world record this year for the highest single carrier bit rate of 1.52 terabits per second over 80km of standard single mode fibre. The record was established by employing a new 128 Gigasample/second converter enabling the generation of signals at 128 Gbaud. What was achieved was the equivalent of simultaneously streaming 1.5m YouTube videos, which is four times the market’s current state-of-the-art solution of 400 Gigabits per second. The effort, said Nokia Bell Labs, will strengthen the ability to develop networks for the 5G era that meet the ever-growing data, capacity and latency demands of industrial Internet of Things (IIoT) and consumer applications. Marcus Weldon, Nokia CTO
networks that can underpin the next industrial revolution.” The company also set a new data rate world record for directly modulated lasers (DMLs), which are crucially important for low-cost, high-speed applications such as data centre connections. The DML team achieved a data rate beyond 400 Gbit/s for links of up to 15km. DATA CENTRES Speaking of data centres, ADVA is currently leading a three-year project to create the “market’s most advanced optical transceiver chiplets”, with the PEARLS consortium using quantum dot technology to integrate lasers onto electro-photonic silicon chips. The chiplets being developed will be key to “tackling urgent bandwidth needs” by enhancing density, flexibility and efficiency in data centre interconnect (DCI) networks, said ADVA. The project, entitled Photonic Embedding of Active Region Laser chips in Silicon (PEARLS), aims to integrate quantum-dot lasers onto silicon-based electro-photonic integrated circuits (ePICs). By combining silicon photonics, BiCMOS electronics and lasers on a single chip, the size and cost of optical transceivers can be “dramatically reduced”, ADVA says. The three-year effort, funded by Germany’s Federal Ministry for Education and Research, involves a consortium comprising ADVA, FormFactor, Fraunhofer
(ICE6) technology, the trial sought to demonstrate how the cost per bit in telecoms networks could continue to be driven down. The ICE6 system uses a 7nm process node DSP/ASIC, a “highly integrated” InP photonic integrated circuit (PIC), high-performance analogue electronics and advanced packaging. The trial showed how network
operators can “rapidly and cost-effectively” address the increasing capacity
demands of new services such as 5G, enhanced broadband and cloud-based
business services,”
Parthi Kandappan, CTO, Infinera
Infinera said. Parthi Kandappan, chief
technology officer at Infinera, added, “The success of this trial proves our ability to transmit 800G high-baud-rate signals across significant distances, which will be instrumental in driving down network costs.” MAKING THE INTERNET MORE ENERGY EFFICIENT Power efficiency is very important when it comes to redesigning lasers for both delivering smooth and cost-effective operations and supporting sustainability. Researchers at Chalmers university recently completed a five-year research project looking at how to make fibre optic communications more energy efficient. Chalmers said supporting current digital lifestyles over the internet was “completely unsustainable” without changes. At the current rate of internet energy use, it said, if no energy efficiency gains were made, “within ten years the internet alone would consume more electricity than is currently being generated worldwide”. Peter Andrekson, professor of photonics at the Department of Microtechnology and Nanoscience at Chalmers, said, “The challenge lies in meeting the inevitable demand for capacity and performance while keeping costs at a reasonable level and minimising the environmental impact.” Chalmers researchers identified the biggest energy drains in today’s fibre optic
IZM, IHP, IHP Solutions, Sicoya, Technion and the University of Kassel in Germany. Jörg-Peter Elbers, senior vice president of advanced technology at ADVA, said, “We’re taking integration and compact design to new levels. By squeezing more technology
onto a single chip than ever before,
we’re creating a platform for
miniaturised optical transceivers able to deliver the space and bandwidth density needed for tomorrow’s DCI networks.”
Jörg-Peter Elbers, SVP, advanced technology, ADVA
He added, “PEARLS not only paves the way for a new generation of intra-data centre transceivers, but also facilitates more compact and cost-effective integrated coherent transmitter-receiver optical sub-assemblies (IC-TROSAs) for inter-data centre applications.” These projects and developments illustrate that the design of lasers and the components and modules around them will continue to be a movable wave for many years to come, supporting the evolving needs of applications, different networks and the web and cloud ecosystem.
systems. With this knowledge they then designed and built a concept for a system for data transmission which consumes as little energy as possible. Optimising the components of the system against each other resulted in “significant” energy savings. Some of the most energy- intensive components
and president of Nokia Bell Labs, said, “We are pushing the envelope and redefining the limits of what’s
are error-correction data chips, which are used in optical systems to compensate for noise and interference.
possible. This optical research is proof of even faster and more robust
Marcus Weldon, Nokia CTO & president, Nokia Bell Labs
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| ISSUE 22 | Q4 2020
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