A method of making a microstructured optical fiber including loading the core and cladding materials of the fiber with hydrogen and deuterium at a loading temperature； annealing the fiber at a selected temperature Tanneal； pumping the fiber with radiation； and reducing the temperature of the fiber and storing the fiber at the reduced temperature before the step of pumping the fiber； and wherein the method allows the hydrogen and the deuterium to become bound to the core material and the cladding material.
