Photochromic behaviour of thulium-doped silica optical fibres

The first observation of the photochromic effect in thulium-doped silica fibres has been presented. The fact that the particular transmissive state is permanently recorded at room temperature in these doped silica glass fibres may find useful memory applications. Also, the possibilities of making rearrangeable absorptive gratings in the bulk material or fibre look interesting.