Effect of windmill-like-shaped defect on TM photonic band gaps of two-dimensional square-lattice photonic crystals

Abstract

A novel windmill-like-shaped defect was introduced in two-dimensional square-lattice photonic crystals consisting of circular dielectric rods. The photonic band gap (PBG) and defect modes were numerically analyzed using the plane wave expansion method. We studied the influence of the translation distance and the rotation angle of defect on the photonic band gap. The results show that the symmetry of defect may affect the width of PBG. The transverse magnetic (TM) band-gap first increases and then decreases with increased translation distance. For a translation distance of 0.66a, the width of TM band-gap reached it’s widest value of 0.05057 (ωa/2πc). Additionally, we studied the influence of the rotation angle of the defect on the TM band-gap with a fixed translation distance of 0.66a. We discovered that square-lattice photonic crystals with a rotated windmill-like-shaped defect can generate a larger photonic band gap, and the largest width can reach up to 0.05307 (ωa/2πc) with a rotated angle of 10°.

Keywords

• Windmill-like-shaped defect
• Photonic crystal
• Plane wave expansion method
• Symmetry of defect
• TM Photon band gap