Measurements of the electrical and optical properties of gallium
infiltrated into 3D photonic crystals will be presented. These
metallic photonic crystals have been fabricated by filling artificial
silica opals having a lattice period 300 nm by pure (99.999%) gallium
under high pressure (1 kbar) at high temperature (1000 C). Temperature
dependence of dc-electrical conductivity was measured from 100
to 300 K. Data on optical reflectivity have been obtained in
the wavelength range between 0.3 to 50 microns. Comparison of
the experimental data with theoretical predictions will be
discussed.