Band gap engineering in 2D photonic crystals: the influence of element shape and rotational angle

The influence of the element shape and rotational angle on the band gap structure of 2D photonic crystals is investigated. Elements of triangular and hexagonal shape, organised in triangular lattices, are considered. Generally, for elements having a regular polygon shape, the lowest band gaps calculated are found to correspond to those for equivalent circular elements with a smaller material fraction. The size and location of the band gaps are strongly affected by decreasing the structural symmetry, through changing the element shape, its rotational angle relative to the lattice, or a combination of the two. This allows absolute band gap engineering. Example geometries show large absolute band gaps.