The effects of Er³⁺ ion concentration on 2.0-μm emission performance in Ho³⁺/Tm³⁺ co-doped Na₅Y₉F₃₂ single crystal under 800-nm excitation*

Abstract

Na5Y9F32 single crystals doped with ∼ 0.8-mol% Ho3+, ∼ 1-mol% Tm3+, and various Er3+ ion concentrations were prepared by a modified Bridgman method. The effects of Er3+ ion concentration on 2.0-μm emission excited by an 800-nm laser diode were investigated with the help of their spectroscopic properties. The intensity of 2.0-μm emission reached to maximum when the Er3+ ion concentration was ∼ 1 mol%. The energy transfer mechanisms between Er3+, Ho3+, and Tm3+ ions were identified from the change of the absorption spectra, the emission spectra, and the measured decay curves. The maximum 2.0-μm emission cross section of the Er3+/Ho3+/Tm3+ tri-doped Na5Y9F32 single crystal reached 5.26 × 10−21 cm2. The gain cross section spectra were calculated according to the absorption and emission cross section spectra. The cross section for ∼ 2.0-μm emission became a positive gain once the inversion level of population was reached 30%. The energy transfer efficiency was further increased by 11.81% through the incorporation of Er3+ ion into Ho3+/Tm3+ system estimated from the measured lifetimes of Ho3+/Tm3+- and Er3+/Ho3+/Tm3+-doped Na5Y9F32 single crystals. The present results illustrated that the Er3+/Ho3+/Tm3+ tri-doped Na5Y9F32 single crystals can be used as promising candidate for 2.0-μm laser.

Original Na5(Lu1–x–yGdxYy)9F32: Pr3+/Ho3+ Hybrid Single Crystals for Efficient ∼2.9 μm Mid-Infrared Emission

“…However, they decrease rapidly with the addition of Pr 3+ ions for the HP sample due to the occurrence of the energy transfer process from Ho 3+ : 5 I 7 to Pr 3+ : 3 F 2 ions as displayed in Figure . Double-exponential fitting can well analyze the lifetimes of Ho 3+ /Pr 3+ -doped samples I = A 1 .25em exp ( − t τ 1 ) + A 2 .25em exp ( − t τ 2 ) where I denotes the luminescence intensity at time t , and τ 1 and τ 2 stand for the rapid and slow lifetimes for exponential components, separately. A 1 and A 2 show the related constants.…”