Sellmeier dispersion and spectroscopic properties of Er3+-doped lutetium gallium garnet single crystal

The authors report growth, refractive index dispersion, optical absorption and Judd-Ofelt spectroscopic properties of Er3+-doped lutetium gallium garnet (Lu3Ga5O12) single-crystal. The crystal was grown by Czochralski technique. The density of the crystal was measured by Archimedes method. Er3+ concentration in the crystal was measured by inductively coupled plasma atomic emission spectroscopy. The measurement results allow to reach that Er3+ ion in the crystal has a desired segregation coefficient similar to 1.0. Refractive index of the crystal was measured as a function of wavelength in the range of 245-1553 nm using an ellipsometer and a prism coupler, and a Sellmeier equation is established for the crystal. Optical absorption of Er3+ in the crystal was studied in the wavelength range of 300-1700 nm and Er3+ absorption cross section spectrum was obtained. Based on the absorption cross section spectrum and the Sellmeier equation, Judd-Ofelt analysis was done for the crystal. Visible, near-infrared and mid-infrared fluorescence spectra and lifetimes of Er3+ in the crystal were measured, and emission characteristics are demonstrated. Spectroscopic knowledge of peaking absorption cross section, oscillator strength, Judd-Ofelt intensity parameters, radiative rate, fluorescence branch ratio, radiative and fluorescence lifetime, and quantum efficiency of some typical Er3+ emissions is obtained.