Planar optical waveguides have been formed in strontium barium niobate single crystals by either proton or heliumion implantation. The profiles of the ordinary and the extraordinary refractive indices are deduced from dark-line mode spectroscopy. Optical barriers with depths to Deltan(e) = 2.6% for protons and Deltan(e) = 5.5% for helium are obtained. By proton implantation we find a very low intensity loss of 0.4 cm(-1) for ordinarily and a higher value of 2.7 cm(-1) for extraordinarily polarized light at 632.8 nm. For helium-implanted waveguides both values are ~4 cm(-1).