Yb31/Er31-codoped Na2O-Al2O3-GeO2-PbO-PbF2 glasses that are suitable for use in fiber lasers, amplifiers, and waveguide devices have been fabricated and characterized. The density, refractive indices, optical absorptions, Judd-Ofelt parameters, and spontaneous-transition probabilities of the glasses have been measured and calculated. Intense and broad 1.53-mm infrared fluorescence and visible upconversion luminescence were observed under 976-nm diode laser excitation. For the 1.53-mm emission band, the full widths at the halfmaximum increase and the peak wavelengths are blueshifted with an increase of PbF2. The stimulatedemission cross sections were calculated from the measured-absorption cross section according to the McCumber theory. The monotonically reduced emission cross section arises from the decreased refractive indices of glasses and the increased linewidth of the infrared fluorescence spectrum. For the upconversion emissions centered at 524, 547, and 660nm, the emission intensity changes remarkably with PbF2 contents from 0 to 15mol%. The quadratic dependence of the green and red emissions on excitation power indicates that a twophoton absorption process occurs under the 976-nm excitation. The relatively long lifetimes of the Er31 4S3/2 and 4F9/2 levels for the NAGF3 glass gives rise to a much more intense upconversion emission.

Er3+-doped 50SiO2-(502x) PbO-xPbF glasses were prepared. The effect of PbF content on refractive indices, densities, absorptionspectra, the Judd-Ofelt parameters Ωt (t52,4,6), fluorescence spectra and the lifetimes of I level of Er in 50SiO2-(502x) PbO-t13-2xPbF glasses were investigated, and the stimulated emission cross-section was calculated from McCumber theory. With increasing PbF2 content in the glass composition, the V parameter, fluorescence full width at half maximum (FWHM) and lifetimes of I level of Ω6 Er increase, while refractive indices and densities decrease. Compared with other glass hosts, the gain bandwidth properties of 31 Er-doped 50SiO2-50PbF glass is close to those of tellurite and bismuth glasses, and has an advantage over those of silicate, phosphateand germante glasses. The broad and flat → emission of Er around 1.55mm can be used as host material for potential broadband optical amplifier in the wavelength-division-multiplexing (WDM) network system.

We report the ultraviolet laser-induced absorption spectra and refractive index changes in bismuth-based silicate glass. A positive maximum refractive index change of 6×10−4 has been observed in bismuth-based silicate glass upon exposure to a pulsed 248nm KrF excimer laser. It is also seen that the changes in the absorbance and refractive index are strongly dependent on glass melting onditions.

Er3+-doped heavy metal oxyfluoride germanate glass suitable for developing potential optical amplifiers and upconversion lasers has been fabricated and characterized. Under 975nm excitation, intense and broad 1533nm infrared fluorescence and visible upconversion fluorescence were observed. For 1533nm emission band, the full width at half maximum (FWHM) is 57nm, the fluorescence lifetime is 5.7ms, and the quantum efficiency is-100%. Efficient 529, 551, and 657nm upconversion emissions correspond to the transitions 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2, respectively. Raman spectrum indicates the important role of fluoride ions in the formation of glass network. The dependence of upconversion intensities on excitation power involves two-photon absorption processes for the three emission bands. The possible upconversion mechanisms are discussed based on the energy matching conditions and the quadratic dependence on excitation power.