Formation of optical planar waveguides on fused quartz by MeV ion implantation

The optical losses and the refractive index change of optical planar waveguides formed by MeV ion implantation were correlated with the experimental ion implantation parameters. Direct ion implantation was performed by means of carbon, silicon and copper ion beams impinging on the substrate surface at normal incidence. The ions were accelerated at energies ranging from 3 to 12 MeV with fluences varying from 1 × 10¹² to 2 × 10¹⁶ ion/cm², according to the type of implanted ion. The modification of the substrate refractive index due to the ion irradiation-induced damage was evaluated using the prism coupler method, and the refractive index profiles were determined by means of a reconstruction method using a multilayer structure approximation. The guiding properties of the waveguides were analysed using the fibre-coupling technique to determine both the optical transmission and transversal modes at 635 nm. The main practical relevance of our research is the obtention of high-quality waveguides at low current density MeV ion implantation (≤80 nA/cm²) without post-implantation annealing.