Disordered laser gain media: Er 3+ doped CaGdAlO 4 and Ca 3Ga 2Ge 4O 14

Abstract

We report on the optical spectroscopy of trivalent erbium ions doped into compositionally disordered oxide host materials, CaGdAlO 4 and Ca 3Ga 2Ge 3O 14. In either material, averaged spectral linewidths of close to 40 cm −1 are measured to be concentration independent up to 5 mol% of the dopant ion. For laser excitation resonant with the 4I 15/2→ 4F 9/2 and 4I 13/2→ 4F 5/2 and 4F 3/2 transitions, intense blue and green upconversion fluorescence is observed. Dips in the upconversion excitation spectra are attributable to radiative energy transfer (or self-absorption) which is known to enhance energy storage and upconversion.