The propagation modes of 2D photonic crystal waveguide used in coupling between conventional dielectric waveguides

We studied the propagation modes of a two-dimensional photonic crystal waveguide and a problem of coupling between conventional dielectric waveguides, using the Fourier series expansion method combined with the absorbing boundary condition of a perfectly matched layer (PML). It is expected to explain the reason of the coupling efficiency between the photonic crystal waveguide and conventional dielectric waveguides.