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The tellurite glass 70TeO2-20WO3-10ZnO in different Tm3+-doping co ncentration were prepared. According to the absorption spectra,the Judd-Oflet strength parameters were calculated by using Judd-Ofelt theory. The spontaneous-emission probabilities,branch ratios and radiative lifetime of each level of Tm3＋ were given.The emission spectra of Tm3＋-doping in various concentrations were studied.The effective bandwidth and stimulated emission cross-section at the peak wavelength of the emission band were also investigated. Aft er comparing the spectral properties at various Tm3＋ concentra tions, we concluded that the luminescence intensity and effective bandwidth were maximum when the Tm3＋-doping concentration ranges from 0.8wt%—1wt%. The Tm3＋-doped tellurite glass is an ideal host for optical ampli fier working on S-band.

The intensity of upconversion emissions of rareearth ions is determined by the maximum phonon energy of glass host. In this paper the intensities of upconversion emissions in Yb3+/Er3+codoped germanatetellurite glas ses upon the excitation of 980nm laser diode were extremely enhanced by replacing PbO wit h Bi2O3 and increasing the size of alkalimetal ions. Rama n spectra show tha t the maximum phonon energies of the glass hosts investigated keep unchanged, wh ile the maximum phonon density decreases on substituting Bi2O3 for PbO and i ncreasing the size of alkalimetal ions. Based on the nonradiative decay rate, it is found that the maximum phonon density is the main reason for the enhanceme nt of upconversion emissions in Yb3+/Er3+codoped germana tetellurite glasses.

A new Er3+-doped tellurite glass has been studied. According to the a bsorp tion spectrum, Judd-Ofelt intensity parameters were determined and used to calcu late the radiation rates, fluorescent branch ratio and radiative lifetimes of Er 3+ in Er3+-doped tellurite glasses. The J-O parameters wer e o btained as follows, Ω2=479×10-20cm2,Ω 4=152×10 -20cm2,Ω6=070×10-20cm2. The stimulated emission cross-sections (σ e=1040×10-21cm2)， of the Er3+ io n 4I13/2→ 4I15/2 transition was calculated using the McCumber th eory. The FWHM(FWH M=655nm) of the 4I13/2→4I 15/2 emission and lifetimes of every level of Er3+ ion were measured and the lifetime of 4I1 3/2 level obtained is 399ms. The spectroscopic properties of Er3+ ion were compared with those in different glasses. These studies indicate that tellu rite glass is much more beneficial for optical fiber amplifiber to realize broad band and high gain amplification.