Proton and helium implanted waveguides in pure and Nd-doped lithium tantalate

By using a Van de Graaff accelerator, optical waveguides are fabricated in pure or Nd-doped lithium tantalate (LiTaO3) crystals by He+ or H+ implantation. The mode spectra of the various waveguides are investigated by dark lines spectroscopy. The effective indices are used to reconstruct the refractive index profiles.