An electronic device may be provided with imaging modules or communications modules. Imaging modules and communications modules may be improved with the use of plasmonic light collectors. Plasmonic light collectors exploit the interaction between incoming light and plasmons in the plasmonic light collector to redirect the path of the incoming light. Plasmonic light collectors may be used to form lenses for image pixels in an imaging module or to form light pipes or lenses for use in injecting optical communications into a fiber optic cable. Plasmonic lenses may be formed by lithography of metallic surfaces, by implantation or by stacking and patterning of layers of materials having different dielectric properties. Plasmonic image pixels may be smaller and more efficient than conventional image pixels. Plasmonic light guides may have significantly less signal loss than conventional lenses and light guides.