Room temperature persistent spectral hole burning in x-ray irradiated Eu3+-doped borate glasses

Irradiation of x-rays has induced room-temperature persistent spectral hole burning (PSHB) in Eu3+-doped borate glasses melted under an inert atmosphere. Defects were formed by x-ray irradiation and these defects, especially electron trapping centers near rare-earth ions in glasses, were responsible for the PSHB. Electrons were released from these defects upon irradiation of a burning light. Photoreduction of Eu3+ to Eu2+ by trapping these electrons resulted in the formation of persistent spectral holes.