Photonic computation is never going to make sense as an alternative to electrical computation.
Among other reasons, you can create an electronic transistor in silicon by using an electrical signal to open and close a gate.
You can't really do this with light, light beams just pass through each other. And the kind of light-carrying media that can be affected by the presence of a control beam respond much slower and less effectively than doped silicon responds to voltage.
This! And optical waveguides are big, and they need to be spaced apart to avoid interference. Speed of light is limiting for such large circuits to be fast.
Among other reasons, you can create an electronic transistor in silicon by using an electrical signal to open and close a gate.
You can't really do this with light, light beams just pass through each other. And the kind of light-carrying media that can be affected by the presence of a control beam respond much slower and less effectively than doped silicon responds to voltage.