Hacker News Reader

Comment by bigcat12345678 | Hacker News Reader

I think silicon photonics are for directly connecting chips on board with other peripherals, in order to save energy and speed of light.

View on HN

Nope; at this point copper is cheaper up to ~3m and optical is for longer links.

I don't think they meant cost, I think they mean like replacing your PCI bus with optical interfaces.

It's not less energy and it's not cheaper; the only advantage is distance.

What about reducing interference? Optics would be better right?

That's true when you compare electrical vs optical links for NICs in datacenters. But this is about Silcon Photonics, which changes the equation significantly. e.g. it can be used for on-chip optical interconnects.

The silicon real estate being used for interconnect fabric PHIs is becoming significant and, unlike compute, do not scale well with node shrinks. On-die photonics means you can cut out a big chunk of your PHIs and avoid the the latency of going to NICs. The PIUMA architecture even used on-die switches to avoid having to use external switches.

https://www.tomshardware.com/news/intel-demoes-8-core-528-th...

Signal integrity is easier with no EMI nor impedance matching needed. These issues get worse as the frequency increases (which is one of the things used to increase throughput).

Umm, are the connections done at a dust free factory or can people connect devices to optical ports like they would for a thumb drive?

Should be a mostly solved problem already. Well, hopefully as optical transceivers are already a standard thing in the networking world.

Optical interconnects are one solution, though bulky. Fusion splicing fibers is another, but does not have the same cleanliness requirements as chip manufacturing; it's often done outdoors today.

Reply on news.ycombinator.com