Spectroscopic properties of YPO4 crystals activated with Ho3+, Er3+, Tm3+

This paper presents a systematic investigation on the spectroscopic properties of YPO4 crystals activated with Ho3+, Er3+ or Tm3+, carried out in order to obtain preliminary information on the device potentialities of these materials. Relevant information about the radiative properties have been obtained by means of the Judd-Ofelt analysis of the polarized absorption spectra, measured at room temperature in the UV–vis–NIR region. The polarized emission spectra have been measured at 77 and 300 K in the visible and in the NIR upon laser excitation, and the transitions of major interest for application have been identified and characterized. The decay profiles of the main emission manifolds have been measured at room temperature in order to obtain information about the non-radiative processes active in the investigated crystals The stimulated emission cross sections have been estimated for the laser transitions in the NIR, indicating that these compounds can be considered suitable active media for laser operation.