Room temperature persistent spectral hole burning of Eu3+ ions doped in sol–gel derived glasses

The persistent spectral hole-burning (PSHB) phenomenon was investigated for Eu3+-ion-doped Al2O3–SiO2 glasses prepared by the sol–gel method. The efficiency of hole burning, burned at low temperature ∼77 K, was proportionally increased with the content of OH groups surrounding the Eu3+ ions. The proposed mechanism for hole burning is the optically activated rearrangement of the OH bonds surrounding the Eu3+ ions. The burned hole was thermally refilled and erased above ∼200 K. On the other hand, the glass irradiated with X-rays showed PSHB up to room temperature. It is considered that the hole is formed by electron transfer between the Eu3+ ions and the excited Eu3+ or defect centers. The lifetime of the hole was estimated as ∼1.5×105 s at 200 K.