undefined | Better HN

0 pointscycomanic10mo ago0 comments

Phase variations will not introduce any issues here, they most certainly are talking about intensity modulation. You can't really (easily) do coherent modulation using incoherent light sources like leds.

SNR is obviously an issue for any communication system, however fiber attenuation is orders of magnitude lower than coax.

The bigger issues in this case would be mode-dispersion, considering that they are going through "imaging" fibres, i.e. different spatial components of the light walking off to each other causing temporal spread of the pulses until they overlap and you can't distinguish 1's and 0's.

0 comments

abdullahkhalids10mo ago

Mode dispersion is frequency dependent phase changes.

cycomanicOP10mo ago

That's chromatic dispersion, mode dispersion is spatial "path" dependent phase changes. Vibration is actually somewhat more relevant because if it wasn't for that we could theoretically undo mode dispersion (we would need phase information though).

That said all of that is irrelevant to what the previous speaker said, vibration induced phase variation as an impairment. Thats just not an issue, vibrations are way too slow to impair optical comms signals.

mycall10mo ago

How do the gravity wave optical paths solve the vibration issues? Couldn't TSMC do something similar?

j / k navigate · click thread line to collapse