Photonics in Data Centers

Many of the world's largest data centers, including those of Amazon, Google, and Microsoft, are located in cold climates like Alaska to reduce cooling energy needs. Microsoft even submerged a small data center underwater to use the sea as a natural coolant.

?Data centers consume about 200 terawatt-hours (TWh) of electricity annually, more than some countries' total energy use. These facilities are extremely energy-intensive, using 10 to 50 times more energy per floor space than typical commercial buildings, accounting for approximately 2% of the total U.S. energy consumption.

Photonics offers two main advantages: very high bandwidth densities—multiple terabits per millimeter—and energy efficiency, enabling data transmission at energies below a picojoule per bit over hundreds of meters or kilometers.

Bandwidth: Moving data electrically is limited due to significant loss at high bandwidths, requiring exponentially more power to move increasing amounts of data. Switching to the optical domain offers better energy efficiency, allowing data to be moved with much lower energy consumption per bit over distances. Unlike electrons, photons, which are bosons, do not interact with each other, enabling higher bandwidths within each wire and pin on a chip.

Electrical systems often suffer from crosstalk and interference due to dense packing. In contrast, optical data can be modulated on different wavelengths, co-propagating within the same fiber or waveguide without interference. This allows for much higher bandwidth per unit area and length.

Low power consumption: Chips can now process data faster than signals can be transmitted in and out, creating a bottleneck due to the need for optical-to-electronic signal conversion. Co-Packaged Optics integrates the optical interface with the switch chip, reducing the distance from inches to millimeters and cutting power consumption by up to 30% in a 51.2 Tb/s switch. Google reported that optical switches reduced electrical usage by over 30%, with lower costs and improved uptime.

Integrated photonics offers numerous advantages for data centers, including high bandwidth, low latency, energy efficiency, compact design, and improved signal integrity. Optical signals, immune to electromagnetic interference, transmit data faster than electrical signals, efficiently managing the vast data volumes in data centers. Integrated photonics also enables the miniaturization of components on a single chip, saving space and enhancing scalability. However, challenges remain, such as integrating with existing electronic infrastructure and managing the manufacturing costs of photonic components. Advances in manufacturing are gradually addressing these issues.

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Ref:

[1] https://medium.com/groveventures/silicon-photonics-revolutionizing-data-centers-at-the-speed-of-light-5a7e25ac335f

[2] https://research.google/pubs/jupiter-evolving-transforming-googles-datacenter-network-via-optical-circuit-switches-and-software-defined-networking/

[3] https://www.globalsmt.net/articles-and-papers/the-future-of-photonics-optics-in-data-centers/