Dy3+-doped phosphate glass fibers for yellow lasers

We report on the fabrication and characterization of Dy³⁺-doped phosphate glass fibers for applications in yellow lasers. The fibers (core/cladding diameters: 11/125μm) were fabricated in the system P₂O₅–Al₂O₃–Ba₂O–K₂O with their core doped with 0.12 at.% Dy³⁺. For bulk glass, the absorption cross-section σ_abs is 0.11×10^-20 cm² at 452.4nm (absorption bandwidth: 8.4nm), in the range well addressed by blue GaN laser diodes. The transition probabilities for Dy³⁺ ions are calculated using the Judd-Ofelt theory. The stimulated-emission cross-section in the yellow σ_SE is 0.36×10^-20 cm² at 574.1nm, and the luminescence lifetime for the ⁴F_9/2 manifold is 818μs, indicating a luminescence quantum efficiency close to unity. μ-Raman and μ-luminescence mapping was performed over the fiber end-facet indicating a homogeneous core composition and a uniform distribution of Dy³⁺ ions.