Coupling and decoupling of electromagnetic waves in parallel 2D photonic crystal waveguides

The behavior of two nearby straight photonic crystal waveguides is analyzed. It is shown that the two guides, considered as a single system, may realize a very efficient wavelength selective directional coupler, that may be used as a channel interleaver in a WDM communications system. In addition, we also show that, by properly designing the geometry of the dielectric region between the guide cores, waveguide decoupling can be obtained. Necessary conditions for this feature to be obtained are analytically derived, and an electromagnetic explanation of the decoupling process is given.