Quality of the rare earth aluminum borate crystals for laser applications, probed by high-resolution spectroscopy of the Yb3+ ion

Abstract A comparative study was performed of the low-temperature high-resolution absorption spectra of the Yb 3+ probe in R 1− x Yb x Al 3 (BO 3 ) 4 ( R  = Y, Tm, Lu) crystals grown by flux technique independently in four different laboratories using different solvents. We show that the incorporation of solvent components into the crystal in the course of crystallization gives rise to spectral satellites of the Yb 3+ 0( 2 F 7/2 ) → 0′( 2 F 5/2 ) absorption lines and assign particular satellites to the Yb 3+ centers near the bismuth and molybdenum impurities (which decrease the transparency of YAB in the UV spectral range). We suggest this spectroscopic method for a rapid analysis of the quality of UV laser crystals and for improvement of growth technologies.