Spectral characteristics of the thulium ion and cascade generation of stimulated radiation in a YAlO3:Tu3+:Cr3+ crystal

Stimulated emission was obtained from Tu3+ ions in YAlO3 crystals doped with 1.0 at.% Tu and 0.1 at.% Cr. The stimulated radiation was generated by the 3F4→3H5(λ1)→3H5→3H6(λ2) cascade at wavelengths λ1 = 2.34 μ and λ1=1.93 μ and the threshold was 3.5 J/cm at 90 °K. A scheme of radiative and nonradiative transitions between the terms was constructed. The absorption and luminescence spectra recorded at 4.2 °K were used to derive the Stark splitting scheme of the 3H4 and 3H6 terms of the thulium ion.