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An investigation of spectroscopic property and energy transfer process of Er3+ doped and Er3+/Yb3+ co-doped germanate glasses is presented. The emission cross section of the 4I11/2 → 4I13/2 transition of Er3+ doped germanate glass is calculated to be 1.2 × 10-20 cm2. The microparameter of energy transfer from Yb3+:2 F5/2 to Er3+:4I11/2 is calculated to be 2.74 × 10-39 cm6/s, and that is not phonon dependent in the quasiresonant process. The intensity of the emission around 2.7 μm is enhanced obviously when Er3+ co-doped with Yb3+. The excited-state relaxation process of Er3+ is adequately described by a combination of the Judd-Ofelt model and the energy-gap law. With the exception of 4I13/2 and 4I11/2 levels, multiphonon relaxation is dominant for all excited states, making it possible to efficiently pump the 1.55 μm 4I13/2 → 4I15/2 and 2.7 μm 4I13/2 → 4I11/2 emission by excitation of Yb3+:2F5/2 and Er3+:4I11/2 at 980 nm. [ABSTRACT FROM AUTHOR]

Intense 2.0 μm emission has been obtained from Ho3+/Tm3+/Yb3+ triply doped fluorophosphate glass pumped by a conventional 980 nm laser diode. The spectroscopic properties and energy transfer mechanisms between Ho3+, Tm3+ and Yb3+ are analyzed. Based on the absorption spectra, the Judd-Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of Ho3+ ions are calculated. It is also found that the 2.0 μm emission of Ho3+ can be greatly enhanced under the excitation at 980 nm by incorporating Tm3+ and Yb3+ simultaneously. Additionally, the micro-parameters of the energy transfer processes are quantitatively analyzed. The energy transfer coefficient from Yb3+ to acceptors and from Tm3+ to Ho3+ can reach as high as 13.14 × 10-40 cm6/s and 23.39 × 10-40 cm6/s, respectively. This Ho3+/Tm3+/Yb3+ doped fluorophosphate glass possessing high energy transfer coefficient and excellent thermal stability is a promising candidate for efficient 2.0 μm laser. [ABSTRACT FROM AUTHOR]

2.7 μm emission properties and energy transfer mechanism of Nd3+/Er3+ co-doped sodium tellurite glasses are investigated in present paper. Absorption and emission spectra were tested to characterize the 2.7 μm emission properties of Nd3+/Er3+ co-doped sodium tellurite glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3+ and Nd3+ ions was proposed. Intense 2.7 μm emission was obtained from Nd3+/Er3+ co-doped sodium tellurite glasses due to the efficient energy transfer from Nd3+ to Er3+ ions under 808 nm LD pumping. Meanwhile, strongly decreased 545 nm up-conversion and 1.5 μm emissions were observed. Additionally, to obtain efficient 2.7 μm emission, the optimized concentration ratio of Nd3+ to Er3+ was found to be 0.5:1 in present glass system. Our results suggest that the present Nd3+/Er3+ co-doped sodium tellurite glass might have potential application in mid-infrared lasers. [ABSTRACT FROM AUTHOR]

Effect of Ce3+ ions introduction on 2 μm emission properties and energy transfer mechanism in Yb3+/Ho3+-doped fluorophosphate glass has been investigated. From the measured fluorescence spectra, strong emission near 2 μm is demonstrated due to the sensitization of Yb3+ and Ce3+. Based on the absorption spectra, the Judd-Ofelt parameters and radiative properties were calculated and compared with those of other glass hosts. In addition, the energy transfer coefficient from Yb3+ to Ho3+ is 9.52 × 10-40 cm6/s in Yb3+/Ho3+/Ce3+ triply doped sample and is three times larger than that in undoped Ce3+ sample. These results suggest that this Yb3+/Ho3+/Ce3+ fluorophosphate glass with excellent thermal stability and efficient energy transfer from Yb3+ to Ho3+ is a good candidate for 2 μm laser. [ABSTRACT FROM AUTHOR]

The fluorescence properties of 2.7 μm emission as well as near infrared emissions in Er3+/Nd3+ doped fluorophosphate glasses are investigated under 800 and 980 nm excitation. The fluorescence dynamics and energy transfer processes between Er and Nd ions in different pumping schemes are reported. Three Judd-Ofelt intensity parameters, energy transfer microparameters, and efficiency have been determined using the Judd-Ofelt and Förster-Dexter theories. The calculated energy transfer efficiency of the Er3+:4I13/2 level to the Nd3+:4I15/2 level is as high as 83.91%. The results indicate that Nd3+ may be an efficient sensitizer for Er3+ to obtain mid-infrared emission and the more suitable pumping scheme of 2.7 μm laser applications for Er3+/Nd3+ doped fluorophosphate glass is 980 nm excitation. [ABSTRACT FROM AUTHOR]