Improved transmission for 60 degree waveguide bend in 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 hexagonal array of dielectric rods with a refractive index n_eff =3.25 is used for this purpose. The proposed bending structure uses a tapered geometry which increases the transmission and decreases the reflected light in the waveguide. Bandwidth is defined as the region where the transmission ratio is higher than 0.5 and equals to 20nm where the central wavelength is at 1330nm. The normalized transmission before and after adding rods in the bending is estimated to be 32% and 78%, also for reflection of light wave before and after tapering to be 68% and 23%. 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.