Spatially Flat In-Phase Supermode in Multicore Hybrid Photonic Crystal Fiber

We propose a novel hybrid multicore photonic crystal fiber in which the air holes between the cores are replaced with high-index rods. Using coupled mode theory and finite element method, we demonstrate that a spatially flat in-phase supermode can be achieved at the resonant wavelengths without mode shaping. Such a design is more robust to perturbations.