Lifetime extending and performance improvements of optical fibers via loading

A method of making a microstructured optical fiber having a core comprising a core material comprising hydrogen and/or deuterium bound to the core material and a cladding comprising a cladding material, where at least a part of the core comprises silica or doped silica and the core having a Germanium content of less than 0.001 at %, where the microstructured optical fiber is a nonlinear fiber in that the microstructured fiber can guide light for at least a range of wavelengths λmin to λmax and for a mode field diameter (MFD) of the fundamental mode over at least a part of the range, the fraction (MFD)/λ is less than or equal to 5, the method comprising the steps of

• loading the core material and the cladding material with hydrogen and deuterium at loading temperature equal to or more than 120° C.;
• annealing the fiber at temperature Tanneal of more than 80° C. for a period of more than 1 hour;
• pumping the fiber for a period of more than 12 hours with radiation having an average power of 1 W or more and a peak power density within the fiber equal to or higher than 100 W/μm2;
• reducing the temperature of the fiber and storing the fiber at the reduced temperature for a period of time 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.