Effects of liquid crystal infiltration on metallic photonic crystals

The effects of liquid crystal (LC) infiltration on the photonic band gaps (PBGs) of two-dimensional (213) metallic photonic crystals (PCs)are investigated by theoretical calculation. Contrary to the LC-infiltrated dielectric photonic crystals, the infiltration of LCs into 2D metallic PCs is found to enlarge PBGs and create another PBGs in a frequency range higher than that of the original PBG. The change of refractive index due to the phase transition of LCs affects both edges of PBGs so that the positions of PBGs show rather large temperature dependence near the phase transition temperature. Thus metallic PCs infiltrated with LCs can overcome the drawbacks of LC infiltration in dielectric PCs, i.e., the band gap narrowing and weak tunabilty of band gap. The usefulness of LC infiltration in the implementation of 2D or 3D tunable metallic photonic crystals is also discussed.