A birefringent reflector from a 1D anisotropic photonic crystal

We demonstrate theoretically that a one-dimensional anisotropic photonic crystal can exhibit an absolute photonic band gap in which the propagation of light is prohibited for all polarizations and for a given incidence plane. Our structure is formed by the combination of a simple finite superlattice, composed of two alternating birefringent biaxial layers, with a cladding layer. The latter is made of the same material as one of the layers constituting the perfect superlattice, but with different orientation and thickness. We discuss whether the birefringence of the layers has a significant impact on the reflection gap. We have found that for reasonable values of structure parameters an absolute band gap can be obtained. Green's function method is used to derive the necessary expressions for our calculation. The effect of different parameters, namely, the orientation of the layers, the filling fraction, etc, is investigated to achieve a birefringent reflector.