Optical characterization of Sm3+ doped phosphate glasses for potential orange laser applications

Abstract

Undoped and Sm3+doped 45P2O5–45Na2O–2Al2O3–8BaO glasses were synthesized by the melt-quenching technique. The glass structure and luminescence properties were investigated by using Raman spectroscopy, scanning electron microscopy (SEM), spectroscopic ellipsometry, Judd-Ofelt theory and photoluminescence. Electron microscopy showed the homogeneity of samples. Raman spectroscopy revealed that the overall structure of the glass was unaffected by the doping of Sm3+ and ellipsometry was used to measure the optical constants. Judd-Ofelt (JO) analysis was performed on the absorption bands of Sm3+ (4f5) and the three phenomenological parameters (Ω2, Ω4, and Ω6) were computed and then used to determine radiative properties such as the radiative transition probability (Ar), the fluorescent branching ratio (βr), the stimulated emission cross-section (σe) and the radiative lifetime (τrad). Photoluminescence (PL) spectrum showed the typical four transitions of Sm3+ at wavelengths of 564, 600, 645 and 703 nm corresponding to 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2, respectively. The spectroscopic quality factors Ω4/Ω6, the predicted lifetime (τrad) calculated using the JO method and the experimentally lifetime (τexp) for the 4G5/2 level were calculated and discussed. The glass color purity is as high as 98%, which makes it a potential candidate for laser emission.