Polarized spectral analysis of Ho3+ ions in biaxial YAlO3 crystal for 2 μm lasers

An Ho3+-doped YAlO3 (Ho : YAP) single crystal has been grown by the Czochralski technique. The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of the crystal are measured at room temperature. The spectroscopic parameters are calculated based on Judd-Ofelt theory, and the effective phenomenological intensity parameters Ω2,eff, Ω4,eff and Ω6,eff are obtained to be 2.89 x 10-20, 2.92 x 10-20 and 1.32 x 10-20 cm2, respectively. The room-temperature fluorescence lifetime of the Ho3+5I7 → 5I8 transition is measured to be 8.1 ms. Values of the absorption and emission cross-sections with different polarizations are presented for the 5I7 manifold, and the polarized gain cross-section curves are also provided and discussed.