Ion implantation proved to be a universal technique for producing waveguides in most optical materials. Tellurite glasses are good hosts of rare-earth elements for the development of fibre and integrated optical amplifiers and lasers covering all the main telecommunication bands. Er 3+- doped tellurite glasses are good candidates for the fabrication of broadband amplifiers in wavelength division multiplexing around 1.55 μm, as they exhibit large stimulated cross sections and broad emission bandwidth. Fabrication of channel waveguides in such a material via N+ ion implantation was reported recently. Parameters of waveguide fabrication in an Er-doped tungsten-tellurite glass via implantation of N + ions were optimized. First single-energy implantation at 3.5 MeV with fluences between 1·10 16 and 8·10 16 ions/cm2 was applied. Waveguide operation up to 1.5 μm was observed. Then double-energy implantations at a fixed upper energy of 3.5 MeV and lower energies between 2.5 and 3.0 MeV were performed to suppress leaky modes by increasing barrier width. Improvement of waveguide characteristics was found by m-line spectroscopy and spectroscopic ellipsometry.