Crystal growth and spectroscopic performances of Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystal as potential yellow laser gain mediums

Abstract

Exploring new Dy3+-doped laser gain medium is still a challenge for constructing efficient yellow solid-state laser at current stage. In this paper, high quality Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals were grown by the high temperature solution method. The crystal structure, chemical composition, phonon energy, polarized absorption and emission spectra, fluorescence lifetime were investigated. The obtained large FWHMs (6nm) and absorption cross-sections (3.87×10-21 cm2) of Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals at 454nm indicate that they can be efficiently pumped by the commercial blue laser diodes. J-O intensity (Ω2, Ω4, Ω6), fluorescence branching rate and radiative lifetime of Dy3+ ions were calculated by J-O theory. Benefiting from the appropriate phonon energy, the emission cross-section of Dy3+: YPO4 crystal at 575nm can reach 5.04×10-21 cm2. Moreover, after co-doping Tb3+ as deactivating ion, the emission cross-section of Dy3+/Tb3+: YPO4 crystal at 575nm was promoted to 5.98×10-21 cm2 by a resonance energy transfer process between the Dy3+-6H13/2 and Tb3+-7F4. Therefore, both Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals are potential candidates for yellow laser gain mediums.