Effect of Ce^3+ doping on the spectroscopic properties and 155 μm laser operation of Er:Yb:Ce:NaY(WO_4)_2 crystal

Er:NaY(WO4)2 and Er:Yb:Ce:NaY(WO4)2 crystals were grown by the Czochralski method. Er:Yb:NaY(WO4)2, Er:Ce:NaY(WO4)2, and Yb:NaY(WO4)2 crystal powders were synthesized by means of the solid-state reaction. The spectroscopic properties of the crystals were investigated, including the absorption and fluorescence spectra and fluorescence decay. The energy transfer efficiency from Yb3+ to Er3+ in Er:Yb:NaY(WO4)2 and Er:Yb:Ce:NaY(WO4)2 was calculated and analyzed. End-pumped by a diode laser at 970 nm in a hemispherical cavity, a 1.84 W quasi-continuous-wave laser around 1.55 μm with a slope efficiency of 17% and an absorbed pump threshold of 1.60 W was achieved in a 1.04 mm thick c-cut Er:Yb:Ce:NaY(WO4)2 crystal. The results show that the Er:Yb:Ce:NaY(WO4)2 crystal with high Ce3+ doping is a candidate for gain medium of low threshold 1.55 μm laser.