Disordered laser gain media: Er3+ doped CaGdAlO4 and Ca3Ga2Ge4O14

We report on the optical spectroscopy of trivalent erbium ions doped into c ompositionally disordered oxide host materials, CaGdAlO4 and Ca3Ga2Ge3O14. 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. Fo r laser excitation resonant with the I-4(15/2) --> F-4(9/2) and I-4(13/2) - -> F-4(5/2) and F-4(3/2) transitions, intense blue and green upconversion f luorescence is observed. Dips in the upconversion excitation spectra are at tributable to radiative energy transfer (or self-absorption) which is known to enhance energy storage and upconversion. (C) 2000 Elsevier Science B.V. All rights reserved.