Mid-infrared emissions and multiphonon relaxation in Dy3+-doped chalcohalide glasses

Effects of Br addition into Ge25Ga10S65 glasses on the mid-infrared emissio ns and multiphonon relaxation of Dy3+ were investigated. Measured lifetimes of three energy levels emitting the infrared fluorescences increased with the addition of Br. Temperature-dependence of the multiphonon relaxation ra tes (W-mp = 1/tau(m) - 1/tau(R) at low concentration of Dy3+) showed the do minance of 5-phonon relaxation process at 375 cm(-1) vibration associated w ith the asymmetric stretching of GeS4 tetrahedra. A decrease in the multiph onon relaxation rates with Br addition is associated with an increase of th e width of the F-6(11/2)-H-6(9/2) manifolds of Dy3+. It resulted in thermal depopulation of the lowest Stark component and thereby, decreased the mult iphonon relaxation rates in Br-containing glasses. (C) 1999 Elsevier Scienc e B.V. All rights reserved.