Magneto-optical and magnetic resonance studies of erbium-doped glasses.

摘要

We have used the magneto-optical techniques of magnetic circular dichroism (MCD), saturated magnetic circular dichroism (SMCD) and optically-detected magnetic resonance (ODMR) to study the local environment of erbium ions in optical glasses. The optical glass series (with erbium concentration noted in 1020 ions/cm3) under study were: aluminosilicates (12.8, 4.7, 0.53), alkali phosphates (15.9, 7.96, 5.57, 3.01, 0.43) and fluorosilicates (9.96, 2.58, 0.83).; Ground state spectroscopic splitting factors, or g-factors ( g), were measured for each host glass using the three techniques. MCD showed no trend in the Faraday C₀/ D₀ parameter (equal to g) within measurement uncertainty for the aluminosilicate and fluorosilicate hosts. The alkali phosphate showed a slight trend, with g-factor increasing with erbium concentration. Measured magnitudes of C₀/D₀ were comparable to other literature reports.; The technique of SMCD monitors the MCD spectral amplitude at a constant wavenumber and temperature while scanning the magnetic field strength to measure the paramagnetic saturation curve of the erbium-doped sample. The aluminosilicate glass had a g-factor of 5.2 at low concentration decreasing to 3.8 at high concentration. The alkali phosphate measured g = 5.8 for low concentration and 7.3 at high concentration. The fluorosilicate measured a constant g-factor within uncertainty for all erbium concentrations, g ∼ 5.5. The results of the SMCD experiment correlated with EXAFS results (coordination number) on the same samples.; ODMR experiments were not successful, as reliable, repeatable electron paramagnetic resonance spectra could not be measured. We concluded that the SMCD technique shows the most promise as it demonstrated enhanced sensitivity to local environment changes as erbium concentration increased in a glass, compared to other more typical structural probes.