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Blue up-conversion fluorescence from the Tm 3+ : 1 G 4 → 3 H 6 (480 nm) transition has been observed from calcium aluminate glass codoped with Tm 3+ /Nd 3+ , The mechanism for the up-conversion process consists of a two-photon process. An excitation beam with a wavelength of 791 nm first excites Tm 3+ to the 3 H 4 level, where Tm 3+ again absorbs the 1060 nm emission from Nd 3+ : 4 F 3/2 → 4 I 11/2 to attain the Tm 3+ : 1 G 4 level. Lifetime and intensity variations with compositions suggest the presence of an efficient energy transfer from Nd 3+ to Tm 3+ , The highest 480 nm emission intensity has been obtained from the glass with 0.1 mol% of Nd 2 O 3 and 0.2 mol % of Tm 2 O 3 .

Emission properties of 2.0 μm fluorescence and the energy transfer between Ho3+ and Tm3+ in 57PbO·25Bi2O3·18Ga2O3 (mol%) glass codoped with Ho3+ and Tm3+ were investigated. Cross-relaxation rates in Tm3+ increased approximately 5 times when the Tm2O3 concentration was increased from 1.0 to 1.5 wt%. Coefficients of the forward Tm3+→ Ho3+ energy transfer were about 15 times larger than those of the Tm3+← Ho3+ backward transfer. Analysis of the energy transfer and gain spectra indicated that the highest gain at the 2.0 μm wavelength region could be achieved from the glass with 1.5 wt% of Tm2O3 and 0.3 wt% of Ho2O3.

Ge–Ga–As–S glasses were investigated to develop efficient host materials for the Er 3+ :2.7 μm fiber lasers. Ge30Ga1As9S60 and Ge30Ga2As6S62 (all in at.%) glasses show good thermal stability and high rare-earth solubility up to 0.3 mol%. Mid-infrared emission with a peak wavelength of 2.76 μm and bandwidth of ∼120 nm was observed in Er3+- and Er3+/Tm3+-doped Ge30Ga2As6S62 glasses. Codoping of Tm3+ significantly reduced the lifetime of the Er 3+ : 4 I 13/2 level due to the energy transfer of Er 3+ : 4 I 13/2 → Tm 3+ : 3 F 4 . Thus, the population inversion between the 4 I 11/2 and 4 I 13/2 levels in Er3+ became possible. In Er3+-doped glasses, the rate of cross-relaxation for the 4 I 11/2 level was approximately 11 times faster than that for the 4 I 13/2 level.

Ge 25 Ga 5 S 70 (at.%) glasses doped with Tm 3+ and Ho 3+ were prepared and their emission characteristics were evaluated with an emphasis on the 2.02 μm fluorescence from Ho 3+ : 5 I 7 5 I → 8 transition. With constant Ho 3+ concentration, intensities of 2.02 μm emission through the excitation of Tm 3+ at 798 nm increased with Tm 3+ content which indicates efficient energy transfer from Tm 3+ to Ho 3+ . Rates of energy transfer also increased with Ho 3+ concentration but competed against the upconversion phenomenon both in Tm 3+ and Ho 3+ .

XPS Ols spectra were recorded for glasses in the binary PbO-Ga2O3 and ternary PbO-Bi2O3-Ga2O3 systems. Large shoulders with chemical shifts of 1.4 to 1.9 eV were observed in the Ols spectra recorded from PbO-Ga2O3 glasses. These shoulders were attributed to the presence of nonbridging oxygens in the structure. The shoulders indicated that, contrary to previous results, PbO was a network modifier as well as a charge compensator and network former. The addition of Bi2O3 reduced the number of nonbridging oxygens and, therefore, it was classified as an intermediate. Ga2O3 seemed to form GaO4− tetrahedra, constituting the backbone of the network structure. Glasses in the PbOBi2O3-Ga2O3 system had their IR cutoff edges located at 7 μm with glass transition temperatures in the range of 320° to 400°C.

(CdAs2−xGex)0.8I0.2 (where x = 0.0–0.4) infrared transmitting glasses were prepared and the effect of Ge on their properties was investigated. The glass-transition temperature, Tg, of these iodide glasses is as high as 300°C which is considerably higher than that of existing iodide glasses. These glasses exhibited a relatively good chemical durability against water and nitric acid. The density and crystallization phenomenon indirectly suggested that the maximum Ge solubility is less than x = 0.2. These new thermally stable glasses show infrared transmittance up to 17 μm which offers a potential for future mid-infrared applications.