Spectroscopic studies and lasing potentialities of Sm3+ ions doped single alkali and mixed alkali fluoro tungstentellurite glasses

Samarium ions doped single alkali and mixed alkali fluoro tungsten tellurite glasses prepared by employing melt quenching technique were characterized by using various spectroscopic techniques such as optical absorption, excitation, emission and decay spectral studies. From the absorption spectral features, the optical band gap energies have been evaluated. By applying the Judd-Ofelt (J-O) theory to the measured oscillator strengths (f(exp)), the best fit J-O parameters are evaluated and used further in evaluating the radiative properties for the prominent fluorescent levels of Sm3+ ions in the as prepared glasses. A strong luminescence in the reddish-orange spectral region has been observed for all the Sm3+ ions doped as prepared glasses. The emission spectra show four emission transitions resulting from the (4)G(5/2) meta-stable state to the lower lying H-6(5/2), H-6(7/2), H-6(9/2) and H-6(11/2) states upon exciting with a 478 nm line of an argon ion laser. CIE chromaticity co-ordinates evaluated from the emission spectral features and found to be falling in reddish-orange region of the visible spectrum. The decay spectral profiles recorded for single alkali fluoro tungsten tellurite glasses were used to estimate the experimental lifetimes and correlated further with radiative lifetimes to estimate quantum efficiency. The stimulated emission cross-sections (sigma(se)) and branching ratios (beta(R)) were estimated from the emission spectra for all the emission transitions. The aforementioned spectral studies carried out on Sm3+ ions doped as prepared glasses allowed us to conclude that, these glasses are best suited for visible reddish-orange lasers.