Pr3+ doped lead tungsten tellurite glasses for visible red lasers

Abstract

Lead tungsten tellurite (LTT) glasses doped with Pr3+ (0.01, 0.1, 0.5, 1.0 and 1.5mol%) ions were prepared by the conventional melt quenching technique. The glasses were characterized by X-ray diffraction, optical absorption and photoluminescence spectra. The glassy nature of LTT host glass has been confirmed through XRD measurements. From the measured intensities of various absorption bands of these glasses, the three phenomenological Judd–Ofelt (J–O) intensity parameters (Ω2, Ω4 and Ω6) have been evaluated by using the standard as well as modified J–O theory. The J–O parameters measured from the modified J–O theory were used to characterize the absorption and luminescence spectra of these glasses. From this theory, various radiative properties like radiative transition probability (AR), total transition probability (AT), branching ratio (βR) and radiative lifetime (τR) have been evaluated for the fluorescent levels of Pr3+ in these glasses. The emission spectra show five emission bands in visible region for which the effective band widths (ΔλP) and emission cross-sections (σse) have been evaluated. Among all the five emission transitions, a transition 3P0→3F2 is more intense and falls in red region. The visible emission spectra, stimulated emission cross-sections and branching ratios observed for all these glasses suggest the feasibility of using these glasses as lasers in red region. The CIE chromaticity co-ordinates were also evaluated from the emission spectra to understand the suitability of these materials for red emission. From the absorption, emission and CIE chromaticity measurements, it was found that 1mol% of Pr3+ ion concentration is quite suitable for LTT glasses to develop bright red lasers from these glasses.