Concentration effect of the near-infrared quantum cutting of 1788-nm luminescence of Tm³⁺ ion in (Y_1-xTm_x)₃Al₅O₁₂ powder phosphor

In the present paper, the concentration effect of near-infrared quantum cutting of Tm³⁺ ion in (Y_1-xTm_x)₃Al₅O₁₂ powder phosphor is studied by means of experiments and calculations. In addition, the absorption spectra, visible-to-nearinfrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that (Y_1-xTm_x)₃Al₅O₁₂ powder phosphor has a strong four-photon near-infrared quantum cutting luminescence of 1788.0-nm ³F₄ →³H₆ fluorescence of Tm³⁺ ion, when excited by 357.0-nm light. It is also found that the up-limit of the four-photon near-infrared quantum cutting luminescence efficiency of (Y_0.700Tm_0.300)₃Al₅O₁₂ powder phosphor is approximately 302.19%. To the knowledge of the authors, this is the first time that a near-infrared quantum cutting efficiency up-limit exceeding 300% has been reported. The results of this manuscript are valuable in aiding the probing of the new generation Ge solar cell.