Growth, polarized spectral properties, and 1.5–1.6 μm laser operation of Er:Yb:Sr₃Gd₂(BO₃)₄ crystal

An Er:Yb:Sr3Gd2(BO3)(4) crystal was grown by the Czochralski method. The polarized spectral properties of the crystal were investigated, including the polarized absorption and fluorescence spectra and fluorescence decay. The fluorescence quantum efficiency of the upper laser level I-4(13/2) of Er3+ ions and the efficiency of the energy transfer from Yb3+ to Er3+ ions were calculated. End-pumped by a diode laser at 970 nm in a hemispherical cavity, a 1.6 W quasi-cw laser at 1.5-1.6 mu m with a slope efficiency of 18% and an absorbed pump threshold of 5.9 W was achieved in a 1.8-mm-thick Z-cut Er:Yb:Sr3Gd2(BO3)(4) crystal. This crystal has a flat and broad gain curve at 1.5-1.6 mu m and so is also a potential gain medium for tunable and short pulse lasers.