Spectroscopic characterization and 3-micrometer CW laser operation of erbium(3+):gadolinium(3) gallium(5) oxygen(12) and erbium(3+):yttrium(3) scandium(2) gallium(3) oxygen(12)

The spectroscopic and 3-{dollar}mu{dollar}m laser properties of {dollar}rm Ersp{lcub}3+{rcub}{lcub}:{rcub}Gdsb3Gasb5Osb{lcub}12{rcub}{dollar} and {dollar}rm Ersp{lcub}3+{rcub}{lcub}:{rcub}Ysb3Scsb2Gasb3Osb{lcub}12{rcub}{dollar} are investigated. The Judd-Ofelt Theory is applied to calculate radiative lifetimes, branching ratios, and radiative quantum efficiencies. The results reveal radiative lifetimes significantly longer than those actually observed for the {dollar}rmsp4Isb{lcub}11/2{rcub}, sp4Isb{lcub}9/2{rcub}{dollar}, and {dollar}rmsp4Ssb{lcub}3/2{rcub}{dollar} states, which indicate that strong quenching processes operate in these media. Radiative quantum efficiencies of 24% and 32% are observed from the {dollar}rmsp4Isb{lcub}11/2{rcub}{dollar} state for GGG and YSGG, respectively.; The role of upconversion is examined in an experiment in which the luminescence which occurs from the {dollar}rmsp4Ssb{lcub}3/2{rcub}{dollar} and {dollar}rmsp4Isb{lcub}9/1{rcub}{dollar} states following chopped, cw pumping is analyzed in two time domains: that resulting from direct excitation and that resulting following upconversion-induced excitation. The ratio of upconversion-induced luminescence to pump-induced luminscence is quantified and applied to a simplified rate model, from which values of the {dollar}rmsp4Isb{lcub}13/2{rcub}{dollar} and {dollar}rmsp4Isb{lcub}11/2{rcub}{dollar} upconversion coefficients, {dollar}alphasb1{dollar} and {dollar}alphasb2{dollar}, are calculated. The calculated {dollar}alphasb1{dollar} is typically larger than the calculated {dollar}alphasb2{dollar}, which partially explains the mechanism by which cw laser oscillation occurs.; The 3-{dollar}mu{dollar}m laser properties of Er:GGG and Er:YSGG are investigated using monolithic laser resonators. The lasers are pumped directly into the {dollar}rmsp4Isb{lcub}11/2{rcub}{dollar} upper state near 0.97 {dollar}mu{dollar}m by either a Ti:sapphire or InGaAs diode laser. Greater than 0.5-W of 2.79-{dollar}mu{dollar}m laser emission and nearly 0.3-W of 2.82-{dollar}mu{dollar}m emission are observed from diode-pumped Er:YSGG and Er:GGG, respectively. The efficiencies and properties of the two host materials are typically very similar, yet YSGG categorically operates more efficiently than GGG.; The spectral and spatial characteristics of the emission are also observed. The lasers typically operate on four or five longitudinal modes. Tunable, single-frequency emission is demonstrated from Er:YAG at 2.94-{dollar}mu{dollar}m. TEM{dollar}sb{lcub}00{rcub}{dollar}-mode operation from GGG and YSGG is observed under Ti:sapphire-pumped conditions; multimode operation is observed from the diode-pumped system.