The influence of structural/shape anisotropy in 2-D photonic crystals

Using the finite-difference time-domain method, photonic bandgaps and defect modes in two-dimensional photonic crystals based on “triangular cylinders” are simulated. Compared with the circular cross-section rods, there is a structural/shape anisotropy in triangular cross-section based cylinders. When all cylinders are rotated for different angles along clockwise or counter-clockwise, a small shift at the high band-edge is observed even if the filling fraction did not change. When defect is introduced in photonic crystals, the defect modes can be adjusted by rotation of cylinders which are in the neighborhood of the defect. All results show that the structural/shape anisotropy of cylinders can be used to adjust the photonic bandgap and defect modes.