Linear- and nonlinear-optical properties of a new gadolinium calcium oxoborate crystal, Ca4GdO(BO3)(3)

Large and good-optical-quality crystals df gadolinium and calcium oxoborate, Ca4GdO(BO3)(3) (GdCOB) have been grown from a melt by the Czochralski pulling method. The crystal is absolutely insensitive to moisture. Linear-and quadratic nonlinear-optical properties of this new monoclinic biaxial berate crystal are reported. The crystal is transparent in the visible and the near IR (from 0.32 to 2.7 mu m) with favorable phase matching conditions for second-harmonic generation. Experimental phase-matching results, measured with a femtosecond broadband pulse parametric generator source tunable from 0.8 to 2.100 mu m, are compared with theoretical predictions. The effective nonlinear coefficients are determined, leading to d(eff) = 1 pm/V for type I crystals in the ZX plane. The damage threshold is as high as 1 GW/cm(2) at 0.532 mu m. The second-harmonic generation conversion efficiency of a Q-switched Nd:YAG laser with a 15-mm long crystal is greater than 50%. These values together with the possibility of growing large crystals make GdCOB an excellent candidate for the next generation of crystals for frequency conversion and parametric processes. (C) 1997 Optical Society of America.