Analysis of Direct Coupling between Conventional Dielectric Waveguide and Photonic Crystal Waveguide

Abstract

Direct coupling of optical power from a conventional dielectric waveguide to a photonic crystal waveguide is analyzed by the finite-difference time-domain (FDTD) method in this work. It is well known that the coupling efficiency is dependent on the wavelength, the structural parameters of waveguides, the small gap between the waveguides, and so on. And we find out that the wavepacket curve of the coupling efficiency decreases as the gap increases. The coupling-efficiency curve has two oscillatory periods. The wave packet is resulting from the Fabry-Perot resonances within the gaps between the facet of the conventional optical waveguide and the distinct-layer pillars in the photonic crystal waveguide.