Frequency conversion of neodymium laser radiation by resonant pumping of YAG crystals activated with Tm3+ and Ho3+ ions

Stimulated emission from Tm³⁺ and Ho³⁺ ions in an yttrium aluminum garnet (YAG) crystal was obtained for the first time by pumping with neodymium laser radiation via the absorption band of Yb³⁺. The stimulated emission wavelength of the Tm³⁺ ions was 2.014 μ and that of the Ho³⁺ ions was 2.09 μ. The room-temperature output energy was of the order of 10 mJ. The experimental results indicated that the efficiency of conversion of the neodymium laser wavelength to the 2 μ. range could be increased to values limited by the Stokes losses.