Concentration-dependent studies of Nd3+-doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm

Nd3+-doped lead-free zinc phosphate glasses with the chemical compositions (60-x) NH4H2PO4 + 20ZnO + 10BaF2 + 10NaF + xNd2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd–Ofelt (J–O) intensity parameters (Ωλ: λ = 2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd3+ ions. Radiative properties such as radiative transition probabilities (AR), radiative lifetimes (τR) and branching ratios (βR) for different excited states were calculated using J–O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands (4F3/2 level to 4I13/2, 4I11/2 and 4I9/2 states) for all the concentrations of Nd3+ ions. Various luminescence properties were studied by varying the Nd3+ concentration for the three spectral profiles. Fluorescence decay curves of the 4F3/2 level were recorded. The energy transfer mechanism that leads to quenching of the 4F3/2 state lifetimes was discussed at higher concentration of Nd3+ ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05 μm.