Fluorescence and persistent spectral hole burning of Eu3+ in Ge–Ga–S–KBr glasses

Fluorescence and efficient persistent spectral hole burning of Eu3+ at 77 K were observed in chalcohalide glasses. The depth of the hole was approximately 30% after a burning process of 1 min with 50 mW power, and it was completely erased with Ar+ laser irradiation. The hole survived room temperature heat treatment and showed good thermal stability. The hole-burning mechanism was most probably the photo-reduction of Eu3+→Eu2+. Fluorescence from Eu3+ decreased with increasing temperature and disappeared at the temperature above ∼130 K.