[tremon]

Yes, signal (non-)interference is a big upside to optical communication. Photon streams don't interact even when passing through the same waveguide, so you can superimpose many bits/streams/connections in the same transmission channel at the same time (using varying wavelengths or polarisation), and two optical channels running side-by-side don't exert a magnetic force on each other either.

The main upside for optical processing (photonics) is in signal switching then, as in this case. Having to receive the multitude of optical signals, converting them to electrical, doing the signal routing and processing in the electrical domain, then converting back to optical for transmission is a lot of busywork.