Tm<sup>3+</sup>/Ho<sup>3+</sup>掺杂碲酸盐玻璃的上转换发光性能与能量转换机制

doi:10.3964/j.issn.1000-0593(2018)01-0302-06

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Abstract The Tm³⁺ single-doped and Tm³⁺/Ho³⁺ co-doped tellurite glasses are prepared by traditional melt quenching technique. The synthesized glasses were characterized with infrared and up-conversion fluorescence spectra has been investigated in terms of the excitation of 808 nm laser, and the up-conversion fluorescence composed of four emission bands centering around 695, 544, 474 and 740 nm wavelengths, respectively. The 740 nm emission band seldom reported is possibly assigned to the Tm³⁺：¹D₂→³F_{2, 3} transition by analyzing the spectra properties of the glass samples and relevant energy transfer mechanism. The intensities of 740, 695 and 474 nm emission in the tellurite glass at the concentration of 0.5 mol% of Tm₂O₃ and 0.3 mol% of Ho₂O₃ are almost 3, 2.5 and 14 times larger than those in the tellurite glass at the concentration of 0.5 mol% of Tm₂O₃, respectively. These obviously indicate that there is backward energy transfer from Ho³⁺ to Tm³⁺. The population for the energy level ¹D₂ (emitting 740 nm red) of Tm³⁺ in Tm³⁺ single-doped tellurite glass is significantly originated from cooperative up-conversion (CU). However, the population for the energy level ³F_{2, 3} (emitting 695 nm red) of Tm³⁺ is not only resulted from the process of CU, but also from the ¹D₂→³F_{2, 3} transition and the relaxation of the level ¹G₄ of Tm³⁺. Hence, the intensity of 695 nm emission is evidently higher than that of 740 nm emission in the samples. Because of the cross relaxation CR2 and CR3, as well as backward resonant energy transfer RET2, there is a net increase of population for the level ¹G₄ (emitting 474 nm blue) of Tm³⁺ in the Tm³⁺/Ho³⁺ co-doped tellurite glass compared to the Tm³⁺ single-doped tellurite glass while the two glasses are conformed with the concentration of Tm³⁺. The net increase of population for the level ¹G₄ of Tm³⁺ is possible to reinforce the multi-phonon relaxation process of this level, emission of 740 nm red light, as well as CU process, and further enhance the population for the level ³F_{2, 3} of Tm³⁺. Therefore, the intensities of red and blue fluorescence in the Tm³⁺/Ho³⁺ co-doped tellurite glass are clearly greater than those in the Tm³⁺ single-doped tellurite glass. The effects of cross relaxation and energy transfer between Tm³⁺ and Ho³⁺ are studied, while the energy transfer mechanism between Tm³⁺ and Ho³⁺ is also further discussed in the work.

Key words：Up-conversion; Tm³⁺/Ho³⁺ doped; Tellurite glasses; Energy transfer

Received: 2017-01-23 Accepted: 2017-05-30

ZTFLH:

O433

Corresponding Authors: CHENG Yun E-mail: chy6677@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2018)01-0302-06 OR https://www.gpxygpfx.com/EN/Y2018/V38/I01/302