Growth and spectroscopic properties of Yb and Nd ions doped Ca3Li0.275Nb1.775Ga2.95O12 (CLNGG) laser crystals

Abstract

A series of CLNGG crystals doped with varying concentrations of Yb³⁺ and Nd³⁺ were successfully grown by the Czochralski method. The structural and physical properties of the grown crystals were systematically characterized. The Raman spectra of the crystals revealed the influence of Yb³⁺ and Nd³⁺ on the local structure. The Yb:CLNGG crystals exhibited a narrow peak at 943 nm, with the full widths at half maximum (FWHM) of ∼ 37 nm, and the absorption cross-sections for 1 at.%, 5 at.% and 10 at.% Yb doping were 3.84 × 10⁻²¹ cm², 5.79 × 10⁻²¹ cm², and 5.83 × 10⁻²¹ cm², respectively, which were suitable for the commercially available (InGaAs/GaAs) pump sources. The Nd:CLNGG crystals exhibited an absorption peak at 808 nm with the FWHM of ∼10 nm. The absorption cross-sections for 1 at.%, 5 at.% and 10 at.% Nd doping were 4.616 × 10⁻²⁰ cm², 3.461 × 10⁻²⁰ cm², and 3.211 × 10⁻²⁰ cm², respectively, making them well-suited for (AlGaAs/GaAs) commercial laser pump sources. The infrared fluorescence spectra of the crystals were also studied. Among Yb:CLNGG crystals, an increasing Yb concentration enhanced the emission intensities at 1026 nm, reaching the maximum FWHM of 40 nm, while the fluorescence lifetimes became longer. Conversely, for Nd:CLNGG crystals, as the Nd ions increased, the emission intensities at 1060 nm decreased, and the lifetimes shortened. The Yb³⁺ and Nd³⁺ doped CLNGG crystals are expected to achieve ultrashort mode-locked and high-energy laser output in the near-infrared band.