Spectroscopic properties, self-frequency doubling, and self-sum frequency mixing in GdAl_3(BO_3)_4:Nd^3+

We present the absorption and emission spectroscopy of GdAl3(BO3)4:Nd3+ as functions of the σ and π polarizations. From the Judd–Ofelt analysis extended to anisotropic crystals, we have determined the parameters Ω2σ=1.455×10-20 cm2,Ω4σ=1.175×10-20 cm2,Ω6σ=2.043×10-20 cm2,Ω2π=0.208×10-20 cm2,Ω4π=0.326×10-20 cm2, and Ω6π=1.257×10-20 cm2. The radiative lifetime of the 4F3/2 level is 293 µs. The σ-polarized stimulated emission cross section was measured to be 3.0×10-19 cm2 at the laser wavelength of 1061.9 nm. No excited-state absorption was found at this wavelength. Green generation by self-frequency doubling was obtained with a yield of 4.3%. Blue generation tuneable in the 436-nm to 443-nm range was obtained with a yield of 7.3% from self-sum frequency mixing.