Spectral photosensitivity and holographic performance of europium-doped fluorophosphate glass

Spectral investigation of europium-doped flourophosphate glass shows photosensitivity in the range of 244 nm to 351 nm. Holographic investigations of the dependence of the achievable refractive-index changes indicate a strong impact of the doping concentration. The refractive-index changes increase with europium concentrations up to 1.0×10²⁰ Eu/cm³; for higher doping levels the effect becomes smaller. Based on these results, refractive-index changes in excess of 10^-3 for optimized material and holographic recording are predicted. About 23% of the initially recorded holographic grating decay in a double-exponential way with time constants of 7 h and 240 h, but the other 77% of the primary refractive-index changes are persistent. The spatial resolution of this material is better than 1 m. PACS 42.40.Lx; 42.40.Pa; 42.70.Ln