Application of coupled-mode formalism to the analysis of holey photonic crystals

Coupled Mode Theory (CMT) is a well-established formalism, which is widely used in the computation of the optical characteristics of photonic devices, matching the model of array of parallel waveguides [1]-[6]. In particular, it is applicable to 2D photonic crystal devices (i.e. arrays of coupled waveguides / phased laser arrays), in which light propagates along the optical axis of the component. So far, CMT applications were limited to devices, in which the refractive index of the core of a solitary element is higher than that of the clad. Thus, photonic devices, based on periodic arrays of holes and utilizing gap guidance mechanism or combination of total internal reflection and gap guidance (e.g. majority of photonic crystal fibers (PCF), several kinds of modern thresholdless lasers [7]-[8]), were unavailable for CMT analysis. In this work, we show, the best of our knowledge for the first time, how the coupled-mode formalism can be applied to holey photonic crystal devices.