FDTD Simulation of Wave Propagating in Waveguide-Crossings at Large Angle

The study of waveguide-crossings is important in the design of integrated optic (IO) components and in the integration of IO circuits. Authors of [2] have employed the beam propagating method (BPM) in the analysis of "Δn" and "2Δn” type passive crossings at small angles (θ n. The BPM neglects reflection and simulates wave propagation in a forward sense, thus it cannot analyze structures with large geometry and material discontinuities or in situation when reflections add up coherently.