Defect centers and room temperature persistent spectral hole burning in X-ray irradiated Eu3+-doped glass

We have investigated the room temperature persistent spectral hole burning of X-ray irradiated Eu3+-doped Al2O3SiO2 glass, prepared by heating at 1000°C and then glasses. The sol–gel-derived Eu3+-doped glass heated in air at 800°C and irradiated with X-ray exhibits the hole spectra at room temperature, while on the other hand no hole is formed in the glass heated at 1000°C. We can attribute these differences to the different formation of the defect centers by the X-ray irradiation. The formation of the activated Eu3+ ions together with the oxygen defect centers plays an important role on the room temperature hole burning. The lifetime of the burnt hole is estimated to be ∼1.5×105 s at 200 K.