Detailed spectral evaluation of rare earth co-doped glasses for photonic applications

We report herein the detailed evaluation of structural and radiative properties of a series of Sm3+ and Gd3+ co-doped lead phosphate glasses having the compositions (58.2-2x) PbO - 40 P2O5 - 1.8 Al2O3 - x Sm2O3 - x Gd2O3, where x = 0.4–1.4 mol%. The synthesized glass samples were investigated for their structural properties using XRD and FTIR spectroscopy. The oscillator strength of the glass samples was evaluated from UV–Vis absorption spectra. Method of least squares fit between experimental and calculated oscillator strengths had been utilized to obtain Judd-Ofelt intensity parameters W2, W4 and W6 for determining the local structure and nature of bonding around rare-earth ions. The radiative and lasing properties were evaluated from intensity parameters such as probability of radiative transition, branching ratio and radiative lifetime. The emission transitions from the excited level 4G5/2 of samarium to the lower manifolds 6H5/2 and 6H7/2 were observed to be most suitable for photonic applications due to their higher values of electric as well as magnetic dipole radiation transition probability, branching ratio, and cross section of stimulated emission. Glass sample PPASG4 had shown enhanced radiative properties as compared to some previously reported glass configurations with similar Sm2O3 content; which suggests it to be potential candidate for lasing applications.