This paper reports that upconversion phenomenon exists in Tm3+-doped tellurite glass by pumping with both 793nm and 1064nm lasers. Strong 785nm two-photon upconversion fluorescence of 1G4 → 3H5 transition and weak three-photon upconversion 710nm, 677nm, fluorescence pumped by 793 nm Ti:Al2O3 laser has been observed firstly in Tm3+-doped tellurite glass. Upconversion has also been observed under excitation at 1064nm.
The upconversion emission spectra of Er3+ single doped and Er3+/Yb3+ codoped tellurite glasses with 974nm excitation were measured, the upconversion mechanism and the influence of Yb3+ concentration on the upconversion emission of Er3+ were discussed, the energy transfer efficiencies and coefficients between Yb3+ and Er3+ were calculated using the measured lifetimes.
The absorption and emission properties of Yb3+ in numerous silica-based glasses have been investigated. The compositional dependence of the absorption cross section, the integrated absorption cross section and the stimulated emission cross section of Yb3+ were studied for various silica-based glass.
Comparative study of spectroscopic properties of Er3+/Tm3+-codoped and Er3+/Tm3+/Yb3+ codoped tellurite glasses under a single wavelength pumping at 980nm were investigated. In the Er3+/Tm3+-codoped tellurite glasses, we have found that there exists fluorescence emissions at both 1.53 and 1.74 μm, which correspond to the transitions of the Er3+:4I13/2→4I15/2 and Tm3+:3F4→3H6, respectively. Tm3+ act as an efficient co-dopant for depopulation of the Er3+:4I13/2 level, and thus reducing the optical amplification efficiency. Meanwhile, the addition of a small amount of Tm3+ to the Er3+ doped tellurite glass causes the quenching of the green up-conversion fluorescence around 524 and 546nm resulting in red visual. In the Er3+/Tm3+/Yb3+ codoped tellurite glasses, fluorescence emissions at both 1.53 and 1.63 μm communication windows were firstly observed. What’ more, The FWHM (fluorescence width at half maximum) at 1.53 and 1.63 μm are 55nm and 50nm, respectively. This novel three earth ions co-doping method could be applied to other low photon energy glasses, which would be possibly used for potential dual wavelength fiber-optic amplifiers to broaden the communication windows.
Spectroscopic properties of Er3+ doped various glasses are investigated experimentally on the basis of Judd-Ofelt theory, McCumber theory, and lifetime measurements. A strong correlation is observed between glass composition and spectroscopic parameters such as Judd-Ofelt intensity parameters Ωt (t=2, 4, 6), emission spectra, and lifetime of 4I13/2 level of Er3+. The emission parameters of Er3+ doped various glasses are discussed from the viewpoints of emission and gain characteristics at the 1.55μm bands. The results show that tellurite glass is an indeed promising material for Er3+ doped to realize broadband and high gain amplification
A new kind of Yb3+ borate laser glass containing high valency cations was reported in this work. B2O3-ZnO and B2O3-BaO glasses were chosen as the base glasses of Yb$3+)-BaO glasses were chosen as the base glasses of Yb3+ ions. Yb3+ ion has a large integrated absorption area in the former and longer fluorescent lifetime in the latter. The effect of Al3+, La3+, Ti3+, Zr4+, Nb4+ Ta5+, W6+ high valency cations on the absorption and fluorescent behaviors of Ba2O3-ZnO- RmOn-Yb2O3 and B2O3-BaO-RmOn-Yb2O3 glasses was examined. Some Yb3+ borate laser glasses with high cross section for stimulated emissions, good stability, good stability against devitrification and lower non-linear refractive index were presented.
P2O5-RO-Yb2O3 phosphate laser glasses were reported in this work. Relationship among the integrated absorption area, fluorescent behaviors of Yb3+ ion and glass components in P2O5-RO-Yb2O3 glasses was examined. Calculated by Fuchtbauer-Ladenberg equation, the stimulated emission cross section of Yb3+ P2O5-RO glass can be larger than 1.5 X 10-20 cm2. The fluorescent lifetime of P2O5-RO-Yb2O3 is usually larger than 1msec. A comprising relationship between stimulated emission cross section and fluorescent lifetime was found in Yb3+ P2O5-RO glass.