Optical absorption and magnetic circular dichroism spectra of neodymium doped fluorozirconate (ZBLAN) glass

Abstract

The optical absorption and magnetic circular dichroism (MCD) spectra of 1% Nd3+ doped fluorozirconate (ZBLAN) glass are reported. The glass composition is 53 mol% ZrF4, 20 mol% BaF2, 20 mol% NaF, 3 mol% AlF3, 3 mol% LaF3 and 1 mol% NdF3. An analysis of the intensity of the absorption spectrum is done in the framework of the Judd-Ofelt theory. The Judd-Ofelt intensity parameters are Ω2 = 1.76(±0.22) × 10−20 cm2, Ω4 = 3.08(±0.30) × 10−20 cm2 and Ω6 = 3.67(± 0.32) × 10−20 cm2. This parameter set is compared with those for Nd3+ in other vitreous matrices. The small value of the Ω2 parameter can be related to the high ionicity (= low covalency) between the neodymium cation and fluoride anions and/or to a relatively high symmetry of the local surrounding of the neodymium ion. Correlation between the intensity parameters and the size of the modifier is not possible because, in fluoride glasses, the lanthanide ions are intermediate elements and can be both in and out the network positions. It is emphasized that one should not correlate too much physical properties to only three phenomenological parameters. The spectral features of the MCD spectra are described qualitatively. The MCD signals show a strong temperature dependence. A negative A-term is found for the 2P12 → 4I92 transition at room temperature. The ratios C0D of the Faraday parameter C0 to the dipole strength D are reported.