It's currently impractical to get optical waveguides to perform comparable to the state of the art for electronics. Optical waveguides are the equivalent of a wire on a chip.

Intel 4 "fin and minimum metal pitch of 30 nm" https://en.wikipedia.org/wiki/5_nm_process - keep in mind, the actual channel is about half that. 15 nm photons are at the extreme end of UV, which is hard enough. But what really kills photonics miniaturization is the diffraction limit. The photons scatter in every direction.

https://www.quora.com/Why-is-semiconductor-technology-not-sh...