Crystal growth, low-temperature spectroscopy and multi-watt laser operation of Yb:Ca3NbGa3Si2O14

We report on the crystal growth, structure, room- and low-temperature (6 K) absorption and emission spectroscopy of a 3 at% Yb3+-doped trigonal ordered langasite-type silicate crystal, Ca3NbGa3Si2O14 (Yb: CNGS). The Rietveld refinement data are presented. Absorption, stimulated-emission and gain cross-sections are determined for the Yb3+ ion in CNGS for π and σ polarizations. The maximum stimulated emission cross-section amounts to σSE = 0.97 × 10−20 cm−2 at 1014 nm (σ-polarization). The Stark splitting of the Yb3+ multiplets is resolved. Microchip laser operation is obtained with both a-cut and c-cut 3 at% Yb: CNGS samples under end-pumping at 976 nm by a Volume Bragg Grating-stabilized diode laser. For the latter cut, the maximum output power reaches 7.61 W at 1048-1060 nm with a slope efficiency of 59%. By varying the output coupling, multi-watt emission over a 50 nm-broad spectral range is achieved.