Search

The optical absorption and magnetic circular dichroism (MCD) spectra of 1% Nd 3+ doped fluorozirconate (ZBLAN) glass are reported. The glass composition is 53 mol% ZrF 4 , 20 mol% BaF 2 , 20 mol% NaF, 3 mol% AlF 3 , 3 mol% LaF 3 and 1 mol% NdF 3 . 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 Ω 2 = 1.76(±0.22) × 10 −20 cm 2 , Ω 4 = 3.08(±0.30) × 10 −20 cm 2 and Ω 6 = 3.67(± 0.32) × 10 −20 cm 2 . This parameter set is compared with those for Nd 3+ in other vitreous matrices. The small value of the Ω 2 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 2 P 1 2 → 4 I 9 2 transition at room temperature. The ratios C 0 D of the Faraday parameter C 0 to the dipole strength D are reported.

Optical absorption and magnetic circular dichroism (MCD) spectra of 1% Pr3+ doped ZBLAN fluorozirconate glass have been recorded at several temperatures between 4.2 K and room-temperature. The dipole strengths of the 4f–4f transitions are parametrized in terms of three phenomenological Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6). The method of moments was used to extract the Faraday parameters from the MCD spectra. While the room-temperature MCD spectra are dominated by A-terms (which have the shape of the first derivative of an absorption curve), C-terms become more important at lower temperature. The temperature dependence of the 3P0←3H4 transition is a typical example. The temperature dependent change of the MCD spectrum can be explained by the differential thermal population of the Zeeman levels from which absorption of left and right circularly polarized light takes place.