Hybrid multicore photonic-crystal fiber for in-phase supermode selection.

We examine a hybrid multicore photonic-crystal fiber, where the cores are separated by high-index solid rods and the microstructure cladding is built on a hexagonal lattice of air holes in silica. Antiresonant reflection from high-index solid rods is shown to assist the field confinement in the cores of such a fiber. When the cores are doped with a laser-active material, the maximum gain is achieved for the in-phase supermode, which translates into a high-quality Gaussian-like beam profile in the far field.