[sounds]

Ok, poor question on my part, but a great answer. Thanks! Yes, wavelength-division multiplexing can expand the capacity of a single strand.

I meant, packet switching.

Switching packets of photons would be done by transitioning from transparent to opaque/inverted polarity/shifted wavelength/etc.

I'm way out of my depth here but an interferometer seems like one method that current research is looking at to accomplish that. What do you think looks the most promising?

[mstresh]

Yes, an interferometer is certainly a very common method to perform switching. What ultimately gets used will depend on the technology/material system. Silica-on-silicon and silicon photonics-based switches will likely use Mach-Zehnder interferometers. MEMS switches currently use movable mirrors or gratings.