Planar optical waveguides were designed and fabricated in an Er-doped Tungsten-Tellurite oxide glass and in a KDy (WO4)2 crystal by swift heavy ion irradiation. 12.5 MeV Au5+ ions were used in the first case and 10.5 MeV N4+ ions in the second one. Irradiated fluences were very low: 7·1014 ions/cm2 in the first experiment, and 4·1015 ions/cm2 ions/cm2 in the second one. Micro Raman studies of both waveguides showed structural changes in the irradiated samples. Ellipsometric measurements showed the existence of ion beam irradiated thin film structures in both samples. M-line spectroscopic measurements were carried out to check functionality of the ion beam irradiated planar optical waveguides. One guided mode was detected in both samples at the wavelength of 632.8 nm both in TE and TM modes. However, amplitude and width of the detected m-lines indicate high propagation losses. According to our previous experiences, stepwise thermal annealing can largely reduce propagation losses, and even allow for guiding at the 1550 nm telecom band.