We present detailed measurements of laser relevant cross sections of thulium doped yttrium-aluminum-garnet (Tm:YAG) and yttrium-aluminum-perovskite (Tm:YAP), including the absorption cross sections for the 3H6 to 3H4 transition near 800 nm, and the absorption and emission cross sections for the transitions between the 3H6 to 3F4 manifolds in the short-wavelength infrared region.
For Tm:YAP we present data for all polarization axes. The measurements were carried out at temperatures ranging from 80 K to 300 K. Furthermore, re-absorption free fluorescence lifetimes of the 3F4 to 3H6 transition at 77 K, 200 K and 295 K were obtained using the pinhole method. We observed a significant enhancement of the fluorescence lifetime when cooling from room temperature to 77 K.
The lifetime was increased from 9.42 ms to 15.22 ms in Tm:YAG and from 3.81 ms to 4.93 ms in Tm:YAP. This indicates that lifetime quenching is present at room temperature, which can be overcome, at least partially, by cryogenic cooling.
These data are presented with the scope to qualify these materials for their use in a new generation of cryogenically cooled, short-wavelength infrared, high-energy class diode pumped solid state lasers utilizing the cross relaxation mechanism for pumping.
Körner, J., Lühder, T., Reiter, J., Uschmann, I., Marschner, H., Jambunathan, V., Lucianetti, A., Mocek, T., Hein, J. and Kaluza, M.C., 2018. Spectroscopic investigations of thulium doped YAG and YAP crystals between 77K and 300K for short-wavelength infrared lasers. Journal of Luminescence.
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