Photonic lanterns: a study of light propagation in multimode to single-mode converters

The "photonic lantern," an optical fibre device that has emerged from the field of astrophotonics, allows for a single-mode photonic function to take place within a multimode fibre. We study and evaluate the modal behaviour of photonic lanterns as well as the conditions for achieving low-loss between a multimode fibre and a "near-diffraction limited" single-mode system. We also present an intuitive analogy of the modal electromagnetic propagation behaviour along the photonic lantern transition in terms of the Kronig-Penney model in Quantum Mechanics.