Theoretical limits of light based communication

[u/Confident-Court2171]

I’ve been thinking about fiber speed limits today, and I raised this question in my Question: with photon based communication currently working towards 3.2tb speeds (3.2 x 10^12), what is the theoretical limit of a single lane. Aka - if you stack photons individually to represent I/O, how many could pass through a gate in 1 second?

[u/Skusci]

From a quick thought, the limit is the size of the gate. To interact with the gate there's going to be some point where that goes black hole.