A co-doped silicate optical waveguide having a core including silica, and oxides of aluminum, germanium, erbium and thulium. The composition concentrations are: Er from 15 ppm to 3000 ppm; Al from 0.5 mol % to 12 mol %; Tm from 15 ppm to 10000 ppm; and Ge from 1 mol % to 20 mol %. In a specific embodiment, the concentration of Er is from 150 ppm to 1500 ppm; Al is from 2 mol % to 8 mol %; and Tm is from 15 ppm to 3000 ppm. A boron-less cladding surrounds the core.