研究了Yb3+/Er3+共掺锗碲酸盐玻璃在980nmLD抽运下的上转换发光光谱，发现随着碱金属离子半径的增大，上转换发光强度明显增强。基质玻璃的Raman光谱显示：玻璃的最大声子能量并不随碱金属氧化物之间的取代而发生变化，表明最大声子能量并不是锗碲玻璃上转换发光强度增大的原因。从玻璃无辐射跃迁的角度分析表明：最大能量声子密度的降低是影响Yb3+/Er3+共掺锗碲玻璃上转换发光强度增大的主要原因。

In order to elucidate the short-rang order structure in the ternary system Na2O-(3-x) SiO2-xGeO2 we employ in this study a quantitative description to determine the molar ratios of Na2O to SiO2 (RSi) and Na2O to GeO2 (RGe) in sodium germanosilicates. The calculated results show that the sodium oxide has no preference for the silicate or the germanate part of the network and there are the same short-rang order units in various Na2O-(3-x) SiO2-xGeO2 glasses. The Raman spectra also confirm the calculated results.

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.

Yb3+-Er3+ co-doped Na2O-GeO2-PbO glass suitable for developing optical fiber lasers and amplifiers has been fabricated. The energy transfer efficiency from Yb3+ to Er3+ was investigated in the glasses with different Yb3+-Er3+ concentration ratios and the maximum energy transfer efficiency was found to be 67% at the Yb3+-Er3+ concentration ratio of 5:1. Subsequently, the studies of upconversion emissions in the visible range were performed. An intense green together with a relatively weak red emission was observed under the excitation of 976nm diode laser. The quadratic dependence of the green emission on excitation power indicates that a two-photon absorption process occurs under a 976nm excitation. However, for the red emission the slope of log-log plot of integrated intensity versus pump power declines with increasing Yb3+ ions content, indicating it is not resulted from a biphotonic process.

The spectroscopic properties of Er3+-doped lead oxyfluorosilicate glasses were analyzed with Judd-Ofelt and McCumber theories. The obtained data suggest that the fluorescence full width at half maximum (FWHM) is related to the X6 parameter, the larger the X6 parameter, and the broader the FWHM. The results showed that Er3+-doped 45SiO2-5Bi2O3-50PbF2 glass had the broadest FWHM (64nm) and large stimulated emission cross-section (0.73×10-20cm2) in these glass samples. Compared with other glass hosts, the gain bandwidth properties of Er3+-doped 45SiO2-5Bi2O3-50PbF2 glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses. The results suggest that Er3+-doped 45SiO2-5Bi2O3-50PbF2 glass can be used as potential host material for developing broadband optical amplifiers in wavelength-division-multiplexingnetwork system.

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.

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.

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.

Upconversion luminescence characteristics of a multi-rare-earth-doped 0.05K2O-0.1ZnO-0.1BaO-0.2PbO-0.2GeO2-0.35TeO2 glass have been investigated under 976nm excitation for potential use in full colour displays.Two luminescence ions, Er3+ and Tm3+, were used as blue, green and red emitters to control the colour of the emitted light. Sensitizer ions, Yb3+, were used to increase the upconversion emission intensity. With the substitution of Er3+ for Tm3+, the intensities of the blue, green and 657nm upconversion emissions simultaneously increase.

In this article, we present a study of a new glass system: lead-germanium-tellurite glasses in the form of 0.05K2O-0.1ZnO-0.1BaO-0.2PbO-xGeO2-(0.55-x) TeO2 with x 0.1, 0.2, 0.3, 0.4, 0.5, and 0.55. Differential temperature analysis of this glass system shows that increasing GeO2 content raises the glass transition temperature (Tg) and suppresses the crystallization tendency in a large temperature range from Tg to the glass melting temperature. The maximum vibrational frequency is intermediate between germanate and fluoride glasses, in the range of 750cm-1 to 820cm-1. Subsequently, Optical absorption, photoluminescence, and upconversion fluorescence were measured for Yb3+, Er3+ co-doped lead-tellurium-germanate glasses. It was found that the full width at half-maximum of the luorescence spectrum at 1534nm decreases and the measured radiative lifetime increases with the replacement of TeO2 by GeO2. Excitation at 976nm into the glass system leads to an intense green emission and a relatively weak red emission. With the addition of GeO2, the increase of red fluorescence and the decrease of green emission in intensity are due to the increase of nonradiative transition rates between the 4S3-2 and 4F9-2 states of Er3+ions. The quadratic dependence of the green and red emissions on excitation power indicates that two-photon absorption process occurs in this glass system excited at 976nm.