The formation of double waveguides in a KTP crystal by combining ion exchange with ion implantation

Double waveguides were produced in potassium titanyl phosphate (KTiOPO4 or KTP) by ion exchange in pure RbNO3 at 340 °C for 45 min, and subsequently ion implantation with 500 keV O ions at a dose of 1 × 1015 ions cm−2. By the prism-coupling method the guided mode spectra as well as the refractive index profiles of the ion-exchanged sample were determined. The relative value of the refractive index distribution of the ion implanted KTP sample in the z direction was simulated, which indicates the formation of double waveguides. The field pattern of the propagation light in the waveguide was collected and studied by the end-coupling method. The near-field pattern of two planar operating waveguides was observed, one upon the other. The irradiation damage as well as the Rb distribution was analysed by means of the Rutherford backscattering spectrometry technique.