Optical properties of Sm3+ doped strontium hexa-aluminate single crystals

Sm3+ doped disordered strontium hexa-aluminate crystals Sr1−xSmyLax−yMgxAl12−xO19 (x = 0.2, y = 0.05, 0.1, 0.15) were grown by Czochralski method. Polarized absorption spectra, as well as emission and lifetime measurements were performed. Strong absorption line located at 404 nm, could be utilized for efficient excitation of material by InGaN/GaN laser diodes. The Judd-Ofelt theory, extended to anisotropic system, has been applied to evaluate the Ωt (t = 2, 4, 6) intensity parameters, radiative transition rates Ar, branching ratios β, and radiative lifetime τr of the fluorescent 4G5/2 level. The emission cross-section for the 4G5/2 → 6H7/2 transition at about 593 nm with the highest value of 1.6 × 10−21 cm2 nm for σ-polarization and an experimental branching ratio β = 49.43%, gives high chance for obtaining laser action in four level operation scheme.