Tunable refraction effects in two-dimensional photonic crystals utilizing liquid crystals.

Tunable refraction effects in two-dimensional photonic crystals utilizing liquid crystals are theoretically demonstrated. Due to liquid crystals with anisotropies, the incident light propagates in photonic crystals at refractive angles different from those in photonic crystals composed of isotropic materials. Moreover, refractive angles can be changed by rotating the directors of liquid crystals. Tunable refraction effects are also discussed for the light with two kinds of frequencies: one is a frequency at the edge of a band gap, and the other is a frequency a little far from the edge of a band gap.