High pressure H ₂ loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO ₂ doped optical fibres

High pressure ‘hydrogen loading’ has been used to sensitise standard singlemode fibres, resulting in the largest reported UV induced index changes for low GeO2 fibres. Grating bandwidths of 4 nm and peak Δns of 5.9 × 10−3 have been reproducibly achieved. Substantial index changes have also been achieved by rapidly heating H2 loaded fibres of various compositions.