Germanium-free silicate waveguide compositions for enhanced L-band and S-band emission and method for its manufacture

A method for manufacturing an optical fiber and the resulting article. The method including the steps of: providing a substrate tube; depositing high purity silica-based cladding layers on the inside of the tube; depositing a germanium-free core comprising a glass including silica, and oxides of Al, La, Er, and Tm; collapsing the substrate tube to form a preform; and drawing the preform to yield an optical fiber. A germanium-free co-doped silicate optical waveguide in accordance with the present invention includes a core material comprising silica, aluminum, lanthanum, erbium and thulium, wherein the concentration of Er is from 15 ppm to 3000 ppm; Al is from 0.5 mol% to 15 mol%; La is less than 2 mol%; and Tm is from 150 ppm to 10000 ppm. In an exemplary specific embodiment the concentration of Al is from 4 mol% to 10 mol%; and the concentration of Tm is from 150 ppm to 3000 ppm. The core may further include F. In an exemplary embodiment, the concentration of F is less than or equal to 6 mol%. The waveguide m