Effective enhancement of ∼2.86 µm mid-infrared emission of Na5Y9F32 single crystal co-doped Ho3+/Pr3+ introduced by Gd3+ ions

Abstract

The optical spectral properties of high-quality Na5Y9F32 single crystals triply incorporated Ho3+/Pr3+/Gd3+ ions prepared successfully via a Bridgman technique were characterized with the help of their absorption spectra, emission spectra, and fluorescence lifetimes. It was discovered that the emission intensity at ∼2.86 µm of Na5Y9F32 co-doped Pr3+/Ho3+ single crystal was boosted obviously by introducing of Gd3+ ions, and it reached its maximum when the concentration of Gd3+ ion dopant was ∼0.7 mol%. The release of more luminescent centers due to the destruction of [Ho3+-Ho3+] ion quenching clusters and variation of the symmetry of crystal field around Ho3+ ions are responsible for the augmentation of ∼2.86 µm fluorescence emission. In addition, the introduction of Gd3+ ion reduced the fluorescence lifetime of Ho3+: 5I7 level, while the Ho3+:5I6 level remained slightly changed, which is beneficial to improve the particle inversion of Ho3+ ion between the 5I6 and 5I7 energy levels to enhance the ∼2.86 µm emission. The results showed that the triply doped fluoride single crystal can become a potentially prospective material for ∼2.86 µm mid-infrared lasers.