Efficient enhancement of ~ 2.85 μm emission in Yb3+/Ho3+ co-doped Na5Y9F32 single crystal via Sm3+ deactivation

Abstract

In current work, we reported a newfangled Sm3+ ion used as a sensitizer to deactivate Yb3+/Ho3+ co-doped Na5Y9F32 single crystal to enhance the ~ 2.85 μm emission. The obtained single crystals were characterized by the X-ray diffraction (XRD), absorption spectra, emission spectra and decay curves. The intensity parameters Ωt(t = 2, 4, 6) of Ho3+ ions were estimated to be (2.72, 1.76, 1.71)×10-20 cm2 according to the measured absorption spectra and the emission cross section at ~ 2.85 μm (Ho3+: 5I6 → 5I7) was calculated to be 11.8 × 10−21 cm2 determining from its emission spectra. Significantly, the ~ 2.85 μm emission intensity was realized about three times enhancement by introducing 0.6 mol% Sm3+ into 1 mol% Yb3+/0.8 mol% Ho3+ co-doped Na5Y9F32 single crystal, while ~ 2.0 μm (Ho3+: 5I7 → 5I8) decreased sharply upon excitation of 980 nm. Furthermore, the Sm3+ takes as an efficient deactivation ion for Ho3+ can be inferred from the fact that the energy transfer efficiency (ETE) from Ho3+: 5I7 to Sm3+: 6H13/2 reaches up to 92.7%. All these favorable optical characteristics revealed that Sm3+/Yb3+/Ho3+ tri-doped Na5Y9F32 single crystals can act as a potential material for ~ 2.85 μm solid-state laser.