Theoretical modeling and experiment of refractive index change in He⁺ ion-implanted KTP waveguide

Abstract

A theoretical model is presented to explain the refractive index change in the ion-implanted KTP waveguide, which includes respective contributions of spontaneous polarization, molar polarization and molar volume, and photoelastic effect. Numerical calculations of refractive indices along different crystalline orientations (X, Y, and Z) as a function of the lattice damage level, determined by Rutherford back-scattering/channeling technique, are performed based on the results from a set of z-cut KTP crystals implanted by 300 keV He+ ions in doses ranging from 4×10(16) to 8×10(16) ions/cm2. The theoretical results show consistency with the experimental data. To our knowledge, this is the first model to comprehensively describe the ion-implanted KTP planar waveguide.

Refractive index profile in ion-implanted neodymium-doped yttrium vanadate waveguide: the relation between index change and lattice damage

“…According to previous research, 19,20 several factors such as spontaneous polarization, molar polarization, and molar volume are assumed to be responsible for the refractive index change in implanted crystals because implant-induced lattice damage could directly cause change of these parameters. In the case of YVO 4 crystal, the impact of spontaneous polarization on the refractive index can be ignored because its tetragonal zircon structure and high lattice symmetry represent the zero value of electro-optic coefficient.…”

Optical confinement achieved in zinc oxide modified by energetic silicon ions beams

“…With some advantages over other techniques, ion implantation/ irradiation provides an efficient and flexible method to fabricate waveguide structure in crystal materials. In most cases implanted-waveguides are produced using energetic light ions (for instance, Hydrogen or Helium) [14,15], taking advantage of the effects caused by nuclear collision processes and displacement damage. This is usually achieved at the expense of using very high fluences, which reduces the practical utility of this method.…”

Visible and near-infrared optical properties of a proton-implanted KTP waveguide

“…On the other hand, light ion implantation causes reduced lattice damage on the ion penetration path (electronic reaction region), thus preserving the crystal structure and optical properties of the waveguide active region [15]. According to former studies, planar waveguides in KTP crystals have been fabricated by light ions (protons and He) using single-energy proton implantation (80-150 keV) [16], double-energy proton implantation (0.60 and 0.55 MeV) [17], single-energy He implantation (150 and 300 keV separately) [18], and combining He implantation (2.0 MeV) with ion exchange [19]. The waveguides produced under these implantation conditions have shown excellent guiding properties in the visible wavelength region.…”