The range of light wavelengths that can reasonably be used for computation is in the hundreds (or thousands) of nanometers. Even the most optimistic approaches

The range of light wavelengths that can reasonably be used for computation is in the hundreds (or thousands) of nanometers. Even the most optimistic approaches for confining such light to small areas, plasmonics, can only realistically give you something like a 10-fold size reduction, putting you at tens of nanometers. The transistors and wires in advanced process nodes have been smaller than that for quite some time, now. Moore's Law is about density. Photon gates cannot compete with electron gates in terms of density.