Ultra-fast optical switching can save overloaded data centers





Ultra-fast optical switching can save overloaded data centers

An illustration of photonically integrated platforms enabling ultra-fast optical circuit switching for data centers. Credit: Aqeel Ahmed/EPFL

EPFL and Microsoft Research scientists demonstrated ultra-fast optical circuit switching using a chip-based soliton comb laser and a fully passive diffraction grating. This particular architecture could enable an energy-efficient optical data center to meet huge data bandwidth requirements in the future.

Services from all hyperscale cloud providers such as Microsoft are powered by huge data centers that employ hundreds of thousands of servers, whose performance is highly dependent on the quality of the network between them. Current data center networks include multiple layers of electrical packet switches interconnected via optical fibers. These systems require electrical-to-optical conversion, which increases overhead and power. To make matters worse, the growing data rates resulting from applications such as AI and data analytics could coexist with the slowdown of Moore’s Law, making it extremely difficult to efficiently run current network architectures that rely on electrical chips. bowls.

Optical Circuit Switches (OCS) are emerging as an exciting option for overcoming bandwidth and scaling issues in data centers. One particularly promising OCS architecture is wavelength switching, connecting different servers with different colors (wavelengths) of light, leading to a flatter network architecture and reducing the need for electrical switches and optical transceivers. Switching different wavelengths of light and routing signals to destination servers is done by a switching element, for example a glass prism through which different wavelengths can be separated by dispersion.

Although OCS technologies are commercially available today, they are extremely slow, meaning they cannot cope with the ever-expanding data center applications while properly utilizing network resources to reduce overhead and improve power consumption.

In a new article published in nature communication, research teams led by Professor Tobias J. Kippenberg of EPFL and by Dr. Hitesh Ballani of Microsoft Research Cambridge successfully demonstrated ultra-fast OCD for data centers using chip-based optics. The research teams have been working together since 2018 as part of the Microsoft Swiss Joint Research Center.

In the proposed architecture, optical microcombs act as a multi-wavelength source providing coherent carriers. Optical amplifiers and waveguide gratings in an array based on semiconductor materials switch and separate or combine the different colors of light.

Optical microcombs, developed by Kippenberg’s group, provide hundreds of equally spaced carriers suitable for many applications. The microcomb sources are generated by nonlinear frequency conversion using a chip-scale silicon nitride microresonator, which offers unique advantages in power and size over the laser arrays conventionally used as multi-wavelength sources.

Silicon nitride microresonators are fabricated using the photonic damascene process, a CMOS-compatible, ultra-low propagation loss technique, which is extremely crucial to create energy-efficient microcomb sources.

The chip-scale indium phosphide-based optical amplifiers, manufactured using commercial foundries, switch between different light colors on sub-nanosecond timescales. This ultra-fast switching between different microcomb carriers is important to meet the performance demands of modern and future data center applications.

A system-level proof-of-concept demonstration showed that packet-by-packet switching data transmission can be achieved and thus has the potential to meet the requirements of data center applications. Finally, the researchers present a unique architecture that uses a central comb system to improve energy efficiency and reduce complexity.

“Soliton microcombs have been used in many important system-level applications since their discovery in 2014, such as LiDAR, long-range data transfer, and optical coherence tomography,” Kippenberg says. “The potential use of microcombs in data centers to meet future bandwidth requirements and reduce power consumption further consolidates the importance of this platform for scientific and technology applications.”

“We were intrigued by the enormous potential of optical microcombs, so it was exciting to work with the EPFL team on applying their industry-leading silicon nitride microcombs technology to potentially future-proof our data center networks,” said Ballani. . “While there is still a long way to go before we can scale our architecture, the rapidly improving performance of microcombs and other on-chip optical devices means the performance gains could be even greater.” Paolo Costa, a co-author with Microsoft Research, added that “this collaboration is a very good example of how we are reshaping the future of our networks from the ground up, both developing and leveraging advanced optical technologies with our academic partners.”


Scalable production of integrated optical frequency combs


More information:
Arslan Sajid Raja et al, Ultra-fast optical circuit switching for data centers using integrated soliton microcombs, nature communication (2021). DOI: 10.1038/s41467-021-25841-8

Provided by Ecole Polytechnique Federale de Lausanne

Quote: Ultrafast optical switching could save overloaded data centers (2021, October 15) retrieved October 15, 2021 from https://phys.org/news/2021-10-ultrafast-optical-overwhelmed-datacenters.html

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