Emission of λ ≈ 2 μ stimulated radiation by holmium in aluminum holmium garnet crystals

Stimulated emission was obtained from Ho³⁺ ions (⁵I₇→⁵I₈ transition) in a new single-component self-activated system with aluminum holmium garnet crystals grown by the Czochralski method. The thresholds of the λ= 2.129 and 2.122 laser emission at 90 °K were 9 and 14 J/cm, respectively. The absorption and luminescence spectra were used in the derivation of the Stark splitting scheme of the ⁵I₇ and ⁵I₈ terms. The lifetime of the ⁵I₇ term was determined (τ ≈ 10 msec).