FORMATION OF PLANAR OPTICAL WAVE-GUIDES IN THE NEW NONLINEAR GADOLINIUM CALCIUM OXOBORATE, CA4GDO(BO3)(3), CRYSTAL BY 2-MEV HE+ IMPLANTATION

A planar waveguide composed of the new nonlinear material, Ca4GdO(BO3) (3) (GdCOB), is reported. This crystal belongs to the calcium oxoborat e family. It has attractive nonlinear properties that can be of great interest in integrated optics applications. We used a method of He+ im plantation to fabricate waveguides in GdCOB crystals by creating a bur ied layer of lowered refractive index a few micrometers beneath the su rface. Both TE and TM modes were observed. Therefore, according to the Y cut of the crystal, refractive-index values of n(x), n(y), and n(z) were obtained. Index profiles were reconstructed by an improved inver se WKB method. The profiles showed a steplike index behavior, indicati ng that the guiding region obtained was of good optical quality. (C) 1 998 Optical Society of America.