We investigated the modification of optical response properties of titanium dioxide (TiO₂) coatings by using ultraviolet-visible absorption spectroscopy and X-ray diffraction. The TiO₂ coatings were prepared on ceramic water-purification filters by e-beam evaporation method. These amorphous TiO₂ were turned into anatase phase by heat treatment at 700 ℃ for 2 hours. The doping of N atoms into the TiO₂ coatings was done by using 70KeV of N⁺ ion implantation with the dose of 1.0 X 10¹⁷ ions/cm², followed by post-irradiation heat treatment at 550 ℃ for 2 hours. Methylene blue test of TiO₂ coatings to solar irradiation showed that the post-evaporation heated TiO₂ was photocatalytic and N-doped TiO₂ reacted to the visible part of solar irradiation.