Figure 3

Upconversion luminescence decay dynamics of the ⁵I₆ (λ_em = 1150 nm) and ⁵I₇ (λ_em = 2000 nm) levels of Ho³⁺ ions as well as ³F₄ (λ_em = 1800 nm) levels of Tm³⁺ ions in the Ho³⁺/Yb³⁺/Tm³⁺/LiNbO₃ single crystals doped with different Mg²⁺ ion concentrations under 980 nm excitation.