LINEAR-OPTICAL AND NONLINEAR-OPTICAL PROPERTIES OF A NEW GADOLINIUM CALCIUM OXOBORATE CRYSTAL, CA4GDO(BO3)(3)

Large and good-optical-quality crystals df gadolinium and calcium oxob orate, Ca4GdO(BO3)(3) (GdCOB) have been grown from a melt by the Czoch ralski pulling method. The crystal is absolutely insensitive to moistu re. Linear-and quadratic nonlinear-optical properties of this new mono clinic 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. Experimenta l phase-matching results, measured with a femtosecond broadband pulse parametric generator source tunable from 0.8 to 2.100 mu m, are compar ed 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 valu es together with the possibility of growing large crystals make GdCOB an excellent candidate for the next generation of crystals for frequen cy conversion and parametric processes. (C) 1997 Optical Society of Am erica.