Artificial immune system optimisation of complete bandgap of bidimensional anisotropic photonic crystals

The artificial immune system (AIS) and the finite element method (FEM) have been used to solve the inverse problem involving the search and the optimisation of the complete photonic bandgap (PBG) of photonic crystal structures with two dimensions periodicity. Triangular lattices composed of silicon (isotropic material) and air and square and triangular lattices composed of tellurium (anisotropic material) and air, have been considered for the validation and analysis of this study, respectively. The PBGs were calculated along the edges of the first Brillouin zone to reduce the high computational effort for this kind of problem. Absolute midgap ratio PBGs of 17.14 and 24.41% have been obtained, for the square and triangular lattices, between the transversal electric TE₁₂ and the transversal magnetic TM₃₄ modes with anisotropic materials, respectively, and 18% for the triangular lattice, between the TE₁₂ and the TM₂₃ modes with isotropic materials.