Formation and anisotropic properties of ion-exchanged KTiOPO4 crystal waveguides

Z-cut KTP crystal waveguides have been fabricated in Ba(NO₃)₂/RbNO₃ bath using ion-exchange process. The effective mode indexes for the TE and TM polarizations are measured by the prism coupling method at the wavelengths of 488, 501.7, 514.5, 532, 632.8 and 1064nm respectively. The refractive index profiles are then determined by the inverse WKB method, which are shown to be accurately modelled by the complementary error function. Surface refractive index increments are computed and shown to be anisotropic. The diffusion coefficient of Rb⁺ in KTP is determined and the formation mechanisms of the waveguide are discussed.