Visible range optical absorption of Er3+ ions in yttrium aluminum borate (YAB) crystals

YAB (YAl3(BO3)4) is a potential self-frequency-doubling laser host. Single crystals of YAB:Er were grown by the top-seeded flux method. The absorption spectra of the visible Er3+ transitions were monitored in YAB crystals in the 9-300 K temperature range by high-resolution Fourier transform spectroscopy. The ground state of the Er3+ ions is 4I15/2, and the energy levels and Stark components of 7 transitions to the 4I9/2, 4F9/2, 4S3/2, 2H11/2, 4F7/2, 4F5/2, and 4F3/2 manifolds were analyzed in detail. The low temperature absorption spectra of Er:YAB consist of sharp lines, the number of which corresponds to the theoretical predictions. This suggests that Er3+ ions uniformly occupy one specific lattice site (yttrium positions) with negligible aggregation at the higher dopant concentration. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)