High Temperature Performance of Femtosecond Laser Written FBGs

High temperature fibre Bragg gratings (FBGs) are essential for certain harsh environment sensing applications. Unlike traditional UV-written type I FBGs, femtosecond laser written silica FBGs can offer higher thermal stability>1000 °C [1], [2]. Here, we investigate different fs-laser FBG inscription parameters to not only achieve high temperature stability, but also explore the FBG structural and spectral changes in the less-well studied extreme temperature (1300 °C) softening and failure regime, including by tapering the heated FBGs.