Decoupling and asymmetric coupling in triple-core photonic crystal fibers

Abstract
We systematically investigate the intercore coupling in triple-core photonic crystal fibers (PCFs). Coupled-mode equations are developed and solved analytically in the linear approximation. We derive the eigenmodes in triple-core PCFs, in particular we model the decoupling mode and test its stability against perturbations. The coupling coefficients and the coupling length are determined experimentally and found to agree extremely well with the calculated results. We describe the propagation of light in triple-core PCFs for different launching conditions.