Upconversion photon quantification of Ho³⁺ in highly transparent fluorotellurite glasses

Multi-photon-excited green, red and oxblood UC emissions have been quantified in highly transparent Ho³⁺/Yb³⁺ doped fluorotellurite (BALMT) glasses under the excitation of 977 nm laser. The net powers of green, red and oxblood emissions are determined to be 88.1, 103.8 and 66.1 μW in 0.196% Ho₂O₃ and 0.752% Yb₂O₃ co-doping case under the excitation power of 870 mW, and the net emission photon numbers are identified to be 242.7 × 10¹², 342.8 × 10¹² and 250.8 × 10¹² cps. The quantum yields (QYs) and luminous fluxes for visible UC emissions of Ho³⁺ are identified as a positive dependency with pumping powers, and when the excitation power density increase to 110.8 W/mm², the QY values for 550 nm green, 650 nm red and 753 nm oxblood UC emissions are up to 0.63 × 10⁻⁴, 0.90 × 10⁻⁴ and 0.65 × 10⁻⁴, respectively. The values of QY in Ho³⁺ doped BALMT glass are one order of magnitude larger than that in NMAG glasses. The macroscopic quantization for UC photon generation from Ho³⁺ in low-phonon fluorotellurite glasses provides a reliable reference for developing compact high-power-density illuminant for remote sensing, radar detection and medical diagnosis.