LGYSB:Nd─High-Performance Lasing in the Near-Infrared Region

Three incongruent melting LaNdGdYSc_4-(BO₃)₄ (LGYSB:Nd) crystals with different Y concentrations (z = 0.15, 0.05, and 0.025) have been grown by the Czochralski method for the first time. The LGYSB:Nd-type crystals exhibit an acentric structure similar to that of the natural mineral huntite CaMg₃(CO₃)₄, with space group R32. The composition of the LGYSB:Nd_3 (z = 0.025) crystal grown from the starting melt composition La_0.628Gd_0.547Y_0.025Nd_0.05Sc_2.75(BO₃)₄ was measured by inductively coupled plasma mass spectrometry method, and it was found to be La_0.6794Gd_0.4105Y_0.0178Nd_0.0381Sc_2.8542(BO₃)₄. The transversal spatial distribution of the refractive index in the LGYSB:Nd_3 crystal was investigated. Third-order nonlinear optical susceptibility χ⁽³⁾ of the LGYSB:Nd_3 crystal was determined from third-harmonic generation experiments with ultrashort (fs) laser pulses. The optical transmission spectrum was measured in the range of 200-2000 nm. The absorption cross-section at 808 nm in σ-polarization was determined to be 1.18 × 10^-19 cm² for the LGYSB:Nd_3 crystal. The 10K absorption spectra revealed that the Nd³⁺ ions occupy only La³⁺ cationic sites in the LGYSB host matrix. The emission cross-section at 1064 nm in σ-polarization was determined to be σ_em(σ) = 1.74 × 10^-19 cm² for the LGYSB:Nd_3 crystal. The fluorescence lifetime was found to be τ = 115 μs for all of the LGYSB:Nd crystals. The LGYSB:Nd_3 laser was operated at an emission wavelength of 1062 nm with very high slope efficiencies of η_sa = 0.74 and η_sa = 0.64 in quasi-cw and cw regimes, respectively.