Spectroscopic Measurements of a High-Concentration Yb³⁺:LiYF₄ Crystal

We describe the spectroscopic measurements of Yb 3+ :LiYF 4 crystal at room temperature. The absorption and the emission spectra are measured with a 40.5 at% Yb 3+ doped crystal. A maximum absorption coefficient of 42 cm -1 for the π polarization is measured at 960 nm with a spectral fullwidth of 12 nm. The upper-state ( 2 F 5/2 ) lifetime is measured to be 2.0 ms. The emission cross section at an oscillation wavelength of 1018 nm for the π and the σ polarizations are measured to be 5.3 ×10 -21 cm 2 and 4.7×10 -21 cm 2 , respectively. The ground-state absorption coefficient at 1018 nm for the π and the σ polarizations are measured to be 4.0 cm -1 and 1.6 cm -1 , respectively.