Reprint of “Lattice damage and expansion in RbTiOPO₄ crystals induced by carbon ion implantation”

In this work, we report on the lattice damage and expansion in RbTiOPO₄ induced by carbon ion implantation over a range of fluence from 2 × 10¹³ to 5 × 10¹³ ions/cm². The samples were analyzed by means of Rutherford backscattering channeling spectrometry using both 1.4 MeV and 2.5 MeV He⁺ ions at a backscattering angle of 170°. The crystal lattice damage and strain of RbTiOPO₄ samples with different fluencies were studied using the high resolution X-ray diffraction. The lattice expansion induced by ion implantation in the channel waveguide was measured by atomic force microscopy. The RbTiOPO₄ waveguides formed by ion implantation keep perfectly transparent as shown in the transmission spectrum, indicated that few color centers remain in the ion implanted region after annealing. Surface indices n_x, n_y and n_z of the samples as a function of ion fluence were studied. The relationship between concentration of displacements per atoms and effective refractive indices in RbTiOPO₄, KTiOPO₄ and KTiOAsO₄ “barrier + well-enhanced” waveguides was investigated.