Frequency up-conversion luminescence properties and mechanism of Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glasses

Abstract

Oxyfl uoride glasses were developed with composition 60GeO 2 •10AlF 3 •25BaF 2 •(1.95-x) GdF 3 • 3YbF 3 •0.05TmF 3 •xErF 3 (x = 0.02, 0.05, 0.08, 0.11, 0.14, 0.17) in mole percent. Intense blue (476 nm), green (524 and 546 nm) and red (658 nm) emissions which identifi ed from the 1 G 4 → 3 H 6 transition of Tm 3+ and the ( 2 H 11/2 , 4 S 3/2 ) → 4 I 15/2 , 4 F 9/2 → 4 I 15/2 transitions of Er 3+ , respectively, were simultaneously observed under 980 nm excitation at room temperature. The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er 3+ ion or the excitation power. In addition, the energy transfer processes among Tm 3+ , Er 3+ and Yb 3+ ions, and up-conversion mechanisms are discussed.

Spectroscopic properties and mechanism of Tm3+/Er3+/Yb3+co-doped oxyfluorogermanate glass ceramics containing BaF2nanocrystals

“…As seen from the inset, the UC emission intensity of the 4 F 9/2 → 4 I 15/2 transition is linearly varied with the heat treatment temperature, whereas the emission intensity of the 4 S 3/2 → 4 I 15/2 transition increases in proportion to the square of the heat treatment temperature. This result indicates that the mechanism for green UC luminescence can be ascribed to the ET process and red UC luminescence may relate to excited state absorption (ESA); [5] the mechanism for the possible ET process is discussed in Fig. 8.…”

“…[28,29] The maximum phonon energy of BaF 2 (∼ 346 cm −1 [30] ) is much lower than that of oxide (the energy of Ge-O vibration is ∼ 870 cm −1 [31] ). Therefore, the precipitation of BaF 2 nanocrystals in glass ceramic and the entrance of Tm 3+ , Er 3+ or (and) Yb 3+ into BaF 2 crystalline phase make the phonon energy decrease and the interdopant distances substantially shorten, which has an important effect on the ET rate between ions: [5] the energy conversion rate from Yb 3+ to Tm 3+ , Er 3+ increases and the multi-phonon relaxation probability decreases in the glass ceramic. All of these result in intense UC luminescence.…”

“…The up-conversion (UC) luminescence, until now, has been extensively investigated by using rare earth ions-doped glasses, due to their potential applications in fields such as solar cell, three-dimensional display, optical communication, solid-state laser, microscopic imaging, anti-counterfeit technology, sensors, etc. [1][2][3][4][5][6] As is well known, the UC efficiency depends largely on the host material for RE ions since host glass with low phonon energy can reduce the multiphonon relaxation and thus achieves strong UC luminescence. [7,8] Furthermore, to meet the requirements of practical applications, the chemical stability and mechanical intensity of host material should be high enough.…”

Up-conversion luminescence properties and energy transfer of Er 3+ /Yb 3+ co-doped oxyfluoride glass ceramic containing CaF 2 nano-crystals

“…Up-conversion luminescent materials doped with rare earth (RE) ions play an important role in numerous potential applications such as infrared pumped visible eye-safe lasers, three-dimensional display, optical data storage, and medical diagnostics. [1][2][3][4][5] However, the enhancement of the up-conversion luminescence efficiency is still a key problem blocking their practical applications. Consequently, numerous methods, such as doping with sensitization ions or selecting one kind of low phonon energy glass host, have been tried for improving the excitation efficiencies and enhancing the upconversion luminescence.…”

Ag2O dependent up-conversion luminescence properties in Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glasses

“…[6][7][8] All of these make oxyfluorogermanate glass promising host material for technological applications such as new upconverting devices, lasing materials, and optical waveguides and amplifiers. 2,9,10 Another major factor influencing on UC luminescence efficiency is the doped RE ions. Because of the special electronic shell structure, RE can show significant emission spectra in visible and infrared regions due to the excited state absorption, energy transfer (ET), and cross relaxation emission by favorable nonradiative decay mechanisms.…”