Thermal and optical properties of Nd³⁺ ions in K–Ca–Al fluorophosphate glasses

Fluorophosphate glasses of composition (P₂O₅–K₂O–Al₂O₃–CaO–CaF₂)-doped with various Nd₂O₃ concentrations were prepared by a melt quenching technique and their thermal, vibrational and optical properties were investigated. Thermal stability of the fluorophosphate glass has been determined from differential scanning calorimetric thermograph. The vibrational modes of the present glass have been studied using Raman spectrum. The intensity parameters, Ω_λ (λ=2, 4 and 6) as well as radiative properties for the ⁴F_3/2 level of Nd³⁺ ion, have been evaluated from the absorption spectra of 1.0 mol% Nd₂O₃-doped glass using the Judd–Ofelt theory. Strong near infrared emission at 1.06 =m attributed to ⁴F_3/2→⁴I_11/2 transition has been obtained for all the glasses upon 806 nm diode laser excitation. Decay analysis has been carried out and found that the lifetime for the ⁴F_3/2 level of Nd³⁺ ion was found to be higher compared to the other Nd³⁺-doped glass host matrices. The quantum efficiency and saturation intensity have been determined to be 93% and 2.32×10⁸ W/m², respectively for 1.0 mol% Nd₂O₃-doped glass. The results indicate that the present glasses could be useful for 1.06 µm laser applications. - Highlights: • Nd³⁺-doped K–Al–Ca fluorophosphate glasses were prepared and characterized. • Raman and DSC measurements have been carried out. • Strong near infrared emission at 1.06 μm (⁴F_3/2→⁴I_11/2 transition) has been found. • Optical properties have been evaluated and compared to other host matrices. • Higher lifetime and quantum efficiency have been noticed in the studied glasses