The spectroscopic properties of Er3+ -doped and Yb3+, Er3+-codoped sodium- and alumino-silicate glasses, potential planar optical waveguide amplifier materials for 1.55 μm, are investigated. With the exception of 4I13/2, multiphonon relaxation is dominant for all Er3+ excited-state multiplets, allowing efficient population of the emitting 4I13/2 state by 4I11/2 excitation around 980 nm. In both glasses, multiphonon relaxation from 4I13/2 is negligible up to 678 K, and the respective 300 K absolute quantum yields are ~0.9 for 0.05 mol% Er3+-doped samples under low-power 4I11/2 excitation. OH− impurities are able to efficiently quench 4I13/2 excitation. Absolute 4I13/2 (Er3+) and 2F5/2 (Yb3+) quantum yields are used to predict an optimum Yb3+, Er3+ concentration range for sensitization. Yb3+ codotation strongly enhances pump-light absorption and increases 4I13/2 population by almost two orders of magnitude in some samples. Relative 2H11/2/4S3/2 upconversion luminescence intensities are shown to be a sensitive measure for the substantial internal sample heating observed in Yb3+ codoped glasses.
© 1996 Optical Society of AmericaPDF Article