Crystal growth and spectroscopic characterization of Dy3+:Na2La4(WO4)7 - A potential yellow laser material

A Dy³⁺:Na₂La₄(WO₄)₇ crystal was grown successfully by the Czochraski method, its spectroscopic properties were investigated in detail. The radiative transition probabilities, fluorescence branching ratios, and radiative lifetime of Dy³⁺ ions were obtained based on the Judd-Ofelt theory. The absorption cross sections at 454 nm are 1.1 × 10^-21 cm² and 0.75 × 10^-21 cm² for σ-polarization and π-polarization, respectively. The stimulated emission cross sections at 574 nm is 1.64 × 10^-20 cm² for π-polarization, and 1.79 × 10^-20 cm² for σ-polarization. The fluorescence lifetime of the ⁴F_9/2 energy level is 218 μs. The results show that Dy³⁺:Na₂La₄(WO₄)₇ crystal is very suitable for commercial 450 nm blue laser diodes pumping, and is a promising yellow laser material.