Spectroscopic properties and laser emission of Yb_0.05Y_0.20La_0.12Gd_0.63Ca₄O(BO₃)₃ mixed oxyborate crystal

Abstract Polarized absorption and emission cross-sections at 850–1100 nm are determined for an Yb-doped La-containing mixed oxyborate crystal of Yb0.05Y0.20La0.12Gd0.63Ca4O(BO3)3. The strongest absorption occurs at 976.8 nm for E//Y, with a cross-section of 1.83 × 10−20 cm2; for the main emission band the dominant polarization proves to be E//Z, for which the maximum cross-section amounts to 0.31 × 10−20 cm2 at 1025.8 nm. Efficient laser emission was generated with X- and Z-cut crystals in a compact plane-parallel resonator; 8.06 W of output power was obtained at 1056–1067 nm in the edge of the main emission band with an optical-to-optical efficiency of 70%; while for laser emission in the long-wavelength sideband, the output power attainable reached 9.19 W at 1080–1081 nm, the optical-to-optical and slope efficiencies being, respectively, 69% and 75%.