Fabrication and properties of gallium metallic photonic crystals

Gallium metallic photonic crystals with 100% filling factor have been fabricated via infiltration of liquid gallium into opals of 300-nm silica spheres using a novel high pressure–high temperature technique. The electrical resistance of the Ga-opal crystals was measured at temperatures from 10 to 280K. The data obtained show that Ga-opal crystals are metallic network with slightly smaller temperature coefficient of resistivity than that for bulk gallium. Optical reflectivity of bulk gallium, plain opal and several Ga-opal crystals were measured at photon energies from 0.3 to 6eV. A pronounced photonic stop band in the visible spectral range was found in both the plain and Ga infiltrated opals. The reflectivity spectra also show increase in reflectivity below 0.6eV; which we interpret as a significantly lower effective plasma frequency of the metallic mesh in the infiltrated opal compare to the plasma frequency in the pure metal.