Anisotropic effects in circular photonic crystals

We analyze accurately in this work the form birefringence effects in circular photonic crystals at optical frequencies. As in dielectric multilayered structures which behave as negative uniaxial crystals the dielectric concentric circular patterns admit two preferred propagation directions defined by an extraordinary and an ordinary refractive index representing two field polarizations. The model is obtained through the geometrical synthesis of the wave front propagation inside the anisotropic structure. The model is applied to Si/SiO₂ dielectric rings photonic crystal which behaves as a Bragg reflector, and to GaAs photonic crystal resonator with cylindrical air holes. The theory is validated by analytical, numerical and experimental results, and can be extended to circular microwave photonic crystals.