Photonic crystals (PCs) have many potential applications because of their ability to control light-wave propagation. We have investigated the tunable bandgap in a three-dimensional anisotropic photonic crystal structures modulated by a nematic liquid crystal. The PC structure composed of an anisotropic dielectric sphere in the liquid crystal medium is studied by solving Maxwell's equations using the plane wave expansion method. The photonic band structures are found to exhibit partial bandgaps for the simple-cubic lattices. Numerical simulations show that the bandgaps can be continuously tuned in simple-cubic lattices consisting of anisotropic dielectric spheres by infiltrating nematic liquid crystals. We analyzed the variations of bandgap by considering various modulation of electric field. Such a mechanism of bandgap adjustment should open up a new application for designing components in photonic integrated circuits.
