A Defect Effect to Light Transmission through Acute Bending Coupled Cavity Waveguide in a Two-Dimensional Photonic Crystal

Light propagation through a coupled-defect waveguide with a 63.5° bend in a two-dimensional (2D) photonic crystal is investigated. The waveguide modes are non-degenerate monopole state and dipole defect state of a square lattice for two different branches. To increase the transmission in the bending waveguide, we propose a method to rotate the localized state by introducing a new type defect with a sheared square rod into coupled cavity. The higher coupling efficiency and transmission in the bending waveguide are obtained with proper shear shift.