Dy³⁺-doped germanate glasses for waveguide-typed irradiation light sources

Intense orange-yellow luminescence was achieved in trivalent dysprosium ion (Dy³⁺) doped waveguide-adaptive sodium magnesium aluminium germanate (NMAG) glasses under ultraviolet (UV) radiation. The dominant 482.5 nm (blue) and 574.5 nm (yellow) peaks correspond to ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 transitions, respectively. The internal quantum efficiency for the ⁴F_9/2 level of Dy³⁺ and the total external quantum yield for the four visible emissions were calculated to be 70.88% and 8.90%, respectively. Slab and channel waveguides were attempted by K⁺-Na⁺ ion-exchange processes and the effective diffusion coefficient D_e was derived to be 0.085 μm²/min, indicating that thermal ion exchange was feasible to fabricate Dy³⁺-doped NMAG glasses waveguide. The efficient visible emissions in Dy³⁺-doped NMAG glasses demonstrate the potential in developing waveguide-typed irradiation light sources for minimally invasive photodynamic therapy.