Optical absorption and photoluminescence studies of Nd3+ doped alkali boro germanate glasses

Optical absorption and photoluminescence studies have been carried out at room temperature in 25 R2O–25 GeO2–49.5 B2O3–0.5 Nd2O3 glass systems, (Composition in mol%, R = Li, Na, K and Rb). Judd Ofelt Intensity parameters and other parameters like Racah (E1, E2 and E3), Slater–Condon–Shortley (F2, F4 and F6) Spin-Orbit Coupling (ξ4f) and Configuration Interaction (α,β and γ) for Nd3+ ion in the glass system are calculated. The variation of the Ω2 parameters are interpreted in terms of the covalency of the RE ion in the glass matrix. Further the hypersensitive transition 4I9/2 → 4 G5/2, 2 G7/2 is analyzed with respect to the intensity ratio IL/IS and is found to be dependent on the type of alkali in the glass matrix. The Photoluminescence studies do not show any appreciable shift in the peak emission wavelength of the 4 F3/2 to 4I11/2 transition with the change in alkali type.

Research Highlights
► Optical Absorption studies are reported in RE doped alkali boro germanate glasses.
► Ωj=2,4,6, Ej=1, 2, 3, Fj=2, 4, 6, ξ4f, α, β and γ for Nd3+ in the glass are calculated.
► The change in the Ω2 parameter is related to the covalency of the RE in the glass.
► HST is analyzed with respect to IL/IS and is dependent on the alkali type.
► The peak emission wavelength of the 4F3/2 to 4I11/2 transition is not changed by the alkali.