Refractive index profiles in YCa4O(BO3)3 and Nd:YCa4O(BO3)3 waveguides created by MeV He ions

YCa4O(BO3)3 (YCOB) is one of the rare-earth calcium oxyborate family of crystals. The crystal has good potential to be used for self-frequency doubling due to its excellent combination of nonlinear and laser properties. We have used MeV He+ ions to make waveguides in YCOB and Nd:YCOB (NdYCOB) crystals. The ion implantation was carried out with 2.8 MeV He+ ions at room temperature. The fluences have varied from 1.5x1016 to 5.5x1016 ions/cm2. The model 2010 prism coupler was used to measure the modes in YCOB and NdYCOB waveguides formed by MeV He+ ion implantation. The refractive index profiles are fitted based on the reflectivity calculation method. We have used TRIM'98 simulation to get the range and damage profiles by MeV He+ ions in YCOB. Especially the refractive index change as a function of fluence is discussed