Room Temperature Persistent Spectral Hole-Burning in Sol-Gel-Derived Glasses Doped with Eu3+ Ions

Persistent spectral hole burning was investigated for the Eu³⁺ ions-doped glasses prepared by a sol-gel method. For the glasses containing OH bonds, persistent spectral hole is burned by the laser-induced rearrangement of the OH bonds surrounding the Eu³⁺ ions, which is thermally unstable to erase up to 200 K. On the other hand, the Eu³⁺-doped Al₂O₃-SiO₂ glasses which are heated under H₂ gas or irradiated with X-ray exhibit room temperature PSHB. The depth of the burnt hole increases as the Al₂O₃ content increases. The hole-formation could be explained by a model of the excitation of the Eu³⁺ ions and subsequent electron transfer with the excited Eu³⁺]^– or oxygen-defect centers in the Al—O bonds. The burnt holes are more stable compared with those burned by the rearrangement of the OH bonds.