Optimization of bandwidth in 60° photonic crystal waveguide bends

A systematic scheme utilizing 2D and 3D finite-difference time-domain calculations to design 60° photonic crystal waveguide bends is presented. The method results in an improved transmission bandwidth from 70 to 160 nm in 2D simulations, and from 50 to 100 nm in 3D simulations. The design principles involve displacements and enlargements of selected holes in the bend regions.