Thermal Stability of Type II Modifications by IR Femtosecond Laser in Highly-Doped Aluminosilicate Glass Optical Fibers

Mastering thermal stability of fiber Bragg gratings (FBGs) in the high temperature regime (>800 °C) have drawn considerable attention for sensing applications. Most components (such as FBGs) fabricated to operate at high temperatures are inscribed into conventional fibers and can usually survive for a short amount of time (few 10’s hours) at temperatures beyond 1000 °C. Therefore, there is a need to develop novel solutions to go beyond these limitations, which ultimately are set by the intrinsic nature of the major glass component (GeO 2 -SiO 2 ). In this context, we investigate the effect of Al 2 O 3 incorporation into the fiber core on the thermal stability of imprinted Type II structures by fs-laser [1] . Aluminosilicate fibers were fabricated using the molten core method. Two fibers labelled High-AS and Low-AS, with a maximum concentration of 51.5 mol% Al 2 O 3 and 42.5 mol% Al 2 O 3 were investigated together with SMF28 for comparison.