Luminescent properties of Tb3+ - doped TeO2-WO3-GeO2 glasses for green laser applications

Different concentrations of Tb3+-doped oxyfluoro tellurite (TWGTb) glasses were prepared by conventional melt quenching technique and characterized for green laser applications. The Judd-Ofelt theory was applied to evaluate various spectroscopic and radiative parameters. The TWGTb glasses exhibit D-5(3) -> F-7(5.3) and D-5(4) -> F-7(6-0) transitions when excited at 316 nm radiation. The variation of intensity of D-5(4) -> F-7(5) (Green) and D-5(3) -> F-7(4) (Blue) transitions and the green to blue (I-G/I-B) intensity ratios were studied as a function of Tb3+ ions concentration. The laser characteristic parameters such as effective bandwidth (Delta lambda(eff)), stimulated emission crosssection (sigma(e)), gain bandwidth (sigma(e) x Delta lambda(eff)) and optical gain (sigma(e) x tau(R)) were determined using the three phenomenological Judd-Ofelt intensity parameters. The fluorescence decay profiles of D-5(4) metastable level exhibit single-exponential nature for all the samples. Based on the experimental results we suggest that the 1.0 mol% of Tb3+-doped TWGTb glass could be a suitable laser host material to emit intense green luminescence at 545 nm.