Enhanced and modulated ∼2.9 μm mid-infrared emission of Ho3+/Pr3+: LiYF4 single crystal by co-doping non active Lu3+ ions

Abstract

A hitherto undeveloped Pr³⁺/Ho³⁺: LiYF₄ single crystal by introducing non-active Lu³⁺ ions was synthesized by a reformative Bridgman technique. The crystalline phases and optical properties of the crystals were characterized using various methods, including absorption spectra, X-ray diffraction (XRD), Rietveld refinement, emission spectra, and lifetimes. The band gaps of Ho³⁺/Pr³⁺: LiYF₄ (Ho³⁺/Pr³⁺: LYF) and Ho³⁺/Pr³⁺/Lu³⁺: LiYF₄ (Ho³⁺/Pr³⁺: LLYF) single crystal were calculated by density functional theory, the value is ∼7.902 eV and ∼7.692 eV, respectively. The ∼2.9 μm emission intensity significantly increased about two times when Lu³⁺ (3.0 mol%) was added to 0.1Pr³⁺/0.5Ho³⁺: LiYF₄single crystal due to the disruption of [Ho³⁺-Ho³⁺] quenching clusters formed by Ho³⁺ ions. The maximum emission cross section of 0.1Pr³⁺/0.5Ho³/3.0Lu³⁺: LiYF₄ single crystal was ∼22.7 × 10⁻²¹ cm². The doping of Lu³⁺ ions reduced significantly the lifetime of ⁵I₇ energy level and mitigates effectively the self-termination phenomenon. Thus, the incorporation of Pr³⁺/Ho³⁺/Lu³⁺ into LiYF₄ single crystal represented a promising choice for a laser gain medium operating at ∼2.9 μm, as well as for other optoelectronic devices.