Simplified computation of Photonic Crystal Multimode Interference devices using TD-beam-propagation method

In this paper, two-dimensional Photonic Crystal Multi-Mode Interference devices having square/triangular lattice patterns of periodic air holes in a planar dielectric slab are numerically considered. Firstly, the dispersion properties of 2D photonic crystal structures are computed by using the plane wave expansion method. With numerical computation and simulation by Alternating Direct Implicit-based time domain beam propagation method, EM wave propagation and field distribution in the (N×N) MMI devices using the photonic crystal structure are discussed. A good equivalent model with 2D PhC structure is applied to analyze the designed structures on the basis of multimode interference effect and self-imaging principle in the MM-wave range.