Tunable reducibility of Brillouin zone and bandgap width in elliptical nanowire arrays

Rotating elliptical nanowire arrays as two-dimensional photonic crystals has been proposed and studied in this Letter.The analysis of the four lowest energy bands and the first bandgap width of some examples illustrates that the rotation and configuration of the primitive cell can have effects on the reducibility of the Brillouin zone.As the central element’s orientation changes,the irreducible Brillouin zone could be expanded to the whole first Brillouin zone.Special attention has been paid to the nanowire arrays with adjacent elements perpendicular to each other,and the irreducible Brillouin zone unexpectedly retracted back to the 1/8 of the first Brillouin zone though the symmetry of elements is lower than that of the square lattice.Meanwhile,the first bandgap width of the perpendicular array can be adjusted by the rotation of each primitive element.