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Comment by contron | Hacker News Reader

I feel the same way about how fiber optics can create bandwidth by just slicing up the spectrum for different channels of data (my rudimentary understanding anyway). I like how even after all this time we find new and clever ways to work with light.

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Even more wild than spectrum slicing is polarisation encoding multiple data streams on the same wavelength.

Is that something in practice (and does it have a name?)? (The thought tickled my brain as QAM/PSK but for light...ish)

Radio is just low frequency light, so all of the same encoding methods apply as-is.

I meant it makes sense! I just never considered it and it's a nifty thought

QAM can absolutely be used in fiber optics communication. Encoding and decoding systems are complicated (I won’t pretend to understand it), but it exists.

Example of a research paper using it: https://www.researchgate.net/publication/290224766_Investiga...

And then doing amplification on that light without converting it back to electrical signals.

fiber optics doesn't slice up anything. it's just a pathway for light to travel.

Wavelength-division multiplexing[1]... it's what they use with fiber-to-the-home to get bidirectional signals with a single strand of fiber. Or the big-boy version is DWDM which ISPs use to stuff dozens of customers on a single strand.

You might also be interested in https://phys.org/news/2026-11-air-holes-silicon-wafers-flat....

[1] https://en.wikipedia.org/wiki/Wavelength-division_multiplexi...

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