Eu³⁺ and Sm³⁺ co-activated aluminum germanate glass channel waveguide as irradiation source for photodynamic therapy

A bright and compact orangish-red fluorescence trace is observed in an Eu³⁺/Sm³⁺ co-doped K⁺Na⁺ ion-exchanged aluminum germanate (NMAG) glass channel waveguide under excitation with a 488 nm Ar⁺ laser. The excitation wavelength range and the emission intensity of Eu³⁺ in NMAG glass are remarkably improved by the sensitization of Sm³⁺, and the energy transfer probability and efficiency are calculated to be 151.2 s^-1 and 25.3%, respectively. Meanwhile, the energy transferred from Sm³⁺ can be efficiently utilized to generate intense fluorescence of Eu³⁺ due to the large spontaneous emission probabilities of the Eu³⁺: ⁵D ₀→⁷F_J (J=1, 2, and 4) transitions that reach up to 68.9, 364.7, and 152.6 s^-1, respectively. Enhanced fluorescence in the Eu³⁺/Sm³⁺-doped NMAG glass channel waveguide, which matches the excitation band of most photosensitizers, holds great promise for photodynamic therapy.