RF Over Fiber: A New Era in Data Center Efficiency

Recommendable! Better ML & AI requires better cables in the data center.

"Summary

• In data-center terms, scaling out involves linking computers, while scaling up packs more GPUs into a computer, challenging copper’s physical limits.
• Copper cables face a phenomenon at high data rates that necessitate wider wires and more power, complicating a data center’s dense connections.
• Point2 and AttoTude propose radio-based cables, offering longer reach, lower power consumption, and narrower cables than copper, without the cost and complexity of optics.
• Startups aim to directly integrate radio cables with GPUs, easing cooling needs and enhancing data-center efficiency.

...

In data-center terms, scaling out means increasing how many AI computers you can link together to tackle a big problem in chunks.

Scaling up, on the other hand, means jamming as many GPUs as possible into each of those computers, linking them so that they act like a single gigantic GPU, and allowing them to do bigger pieces of a problem faster.

The two domains rely on two different physical connections.

Scaling out mostly relies on photonic chips and optical fiber, which together can sling data hundreds or thousands of meters.

Scaling up, which results in networks that are roughly 10 times as dense, is the domain of much simpler and less costly technology—copper cables that often span no more than a meter or two. ...

Later this year, Point2 will begin manufacturing the chips behind a 1.6-terabit-per-second cable consisting of eight slender polymer waveguides, each capable of carrying 448 gigabits per second using two frequencies, 90 gigahertz and 225 GHz. At each end of the waveguide are plug-in modules that turn electronic bits into modulated radio waves and back again. AttoTude is planning essentially the same thing, but at terahertz frequencies and with a different kind of svelte, flexible cable."

RF Over Fiber: A New Era in Data Center Efficiency - IEEE Spectrum "Radio and terahertz links could be better, faster, and cheaper"

Point2’s cables are made up of eight e-Tube fibers, each carrying more than 200 gigabits of data per second.Point2 Technology

 A 1.6-terabit-per-second e-Tube cable has half the area of a 32-gauge copper cable and has up to 20 times the reach. Point2 Technology

Nvidia’s GB200 NVL72 rack-scale computer relies on many copper cables to link its 72 processors together. Lot's of cables!