Tunable complete photonic band gaps of two-dimensional photonic crystals with intrinsic semiconductor rods

We show, from the theoretical calculation, that the two-dimensional (2D) photonic crystals constructed with the square rods of intrinsic semiconductor in the air can exhibit a complete photonic band gap common to s- and p-polarized waves in the THz range. This complete band gap is easily tunable by using the temperature dependence of plasma frequency of intrinsic semiconductors. Thus the 2D photonic crystals constructed with the intrinsic semiconductor rods can be applied to the thermal switches, thermal sensors, and the tunable filters operating in THz range.