Spectroscopy of Tm and Ho in KYF4 single-crystals

We report on the spectroscopic characterization of Tm:KYF4 and Ho:KYF4 single crystals. The energy level splittings are given, as well as the Judd-Ofelt parameters, the polarized absorption and emission cross sections and the energy transfer coefficients. This allows to have a deeper understanding of the Tm-Hocodoped KYF4 system and shows KYF4 to be a promising material for widely tunable and efficient 2 ?m laser operation.