Pulsed and continuous-wave laser operation of TGT-grown Nd,Y-codoped :SrF2single crystal

In this letter we present laser properties of temperature gradient technique (TGT) grown Nd,Y : SrF 2 crystals with Nd 3+ concentrations of 0.4, 0.65 and 0.8 at% and Y 3+ concentration of 10 at%. The noncoated crystal samples, 3.1 or 5 mm long, were pumped by the 796 nm laser diode matching the Nd,Y : SrF 2 absorption peak. In the pulsed pumping regime (pulse-duration 2 ms, frequency 10 Hz), maximum average output power of 75 mW (corresponding to peak power of 3.75 W) was obtained with slope efficiency as high as 51% and optical-to-optical efficiency of 42% with respect to the absorbed pump power. The output beam spatial profile was nearly Gaussian in both axes, oscillations started at the wavelength of 1057 nm. At higher pumping levels, the second emission line at 1051 nm appears corresponding to our fluorescence measurements. Wavelength tuning using a birefringent filter from 1048 to 1070 nm is probably given by the crystal-field splitting of the 4 F 3/2 manifold in Nd 3+ . True-continuous-wave laser operation was also successfully obtained at lower pumping levels with maximum output power of 380 mW and slope efficiency of 28% at the wavelength of 1057 nm.