Design of a high-transmission waveguide bend for Kagome photonic crystal lattice

In this paper, a 60° photonic crystal bending geometry for TM modes of a Kagome lattice is proposed. A two dimensional array of dielectric rods with an effective refractive index equal to 3.25 is used for this purpose. The proposed bending structure has a tapered topology which increases the transmission and decreases the reflection to the input waveguide. A bandwidth of 4 nm, where the central wavelength is at 1330 nm is obtained. Bandwidth is defined as the region where the transmission ratio is higher than 0.8 or equally 1 dB. The simulation is performed with the help of two numerical algorithms which are called finite difference time domain (FDTD) and plane wave expansion (PWE) methods.