ABSTRACT
Andreas Tu¨nnermann and Holger Zellmer Fibre lasers are based on silica fibres consisting of a rare-earth-doped core with a refractice index n1,
generally surrounded by a pure silica-glass cladding of refractive index n2 < n1, so that waveguiding occurs due to total internal reflection on the interface between core and cladding (see chapter A6 and B4.1). The fibre core serves both as active medium and as waveguide for the pump light and the generated laser light. Due to the long interaction length of pump and laser light the fibre design offers high gain and efficiency [24].
