Optical properties of Pr3+, Sm3+ and Er3+ doped P2O5–CaO–SrO–BaO phosphate glass

In this paper, we present the photoluminescence properties of Pr3+, Sm3+ and Er3+ doped phosphate glasses. Optical absorption and emission spectra of lanthanide active ions in P2O5–CaO–SrO–BaO glass have been investigated at room temperature. These glasses have shown strong absorption bands in the near-infrared (NIR) and visible (VIS) region. For Pr3+ doped glass, emission bands centered at 608 nm (3P0 → 3H6 + 1D2 − 3H4), 640 nm (3P0 → 3F2), 686 nm (3P0–3F3) and 723 nm (3P0 → 3F4) have been observed with 480 nm (3H4 → 3P0) excitation wavelength. Of them, 686 nm has shown bright red emission. Emission bands of (4G5/2 → 6H5/2) 560 nm, (4G5/2 → 6H7/2) 600 nm and (4G5/2 → 6H9/2) 645 nm for the Sm3+ phosphate glass, with excitation at (6H5/2 → 4F7/2) 400 nm have been recorded. With regard to the Er3+ phosphate glass, a bright fluorescent green–yellow emission at 546 nm (4S3/2 → 4I15/2) have been observed. Analysis of decay curves of luminescence revealed occurrence of the strong luminescence quenching originating from the 3P0 metastable level of Pr3+ and 4S3/2 state of Er3+ mainly by a multiphonon relaxation processes to 1D2, 4F9/2 levels respectively. Moreover these results are compared with those obtained by using the Judd–Ofelt theory. According to the Judd–Ofelt theory, the Judd–Ofelt intensity parameters Ω2,4,6 were calculated, by which the radiative transition probabilities and radiative lifetimes of luminescent levels were obtained.