Amorphous titanium dioxide ͑TiO 2 ͒ thin films doped with rhodamine 6G ͑R6G͒ were deposited on glass substrates by the sol-gel process. The optical properties of the films were characterized by photoacoustic, excitation, and fluorescence spectroscopies. The absorption spectra of the R6G-doped TiO 2 films exhibited two well-defined absorption regions: an absorption band over 2.0 eV attributed to rhodamine 6G and a band above 3.0 eV corresponding to TiO 2 absorption. While the onset of the R6G

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... orption band was shifted by 0.06 eV towards lower energies as the R6G doping concentration increased within the interval of 0.01-0.10 mol %, the onset to high absorption ͑TiO 2 band͒ for the doped films decreased only by 0.01 eV within the same interval. In addition, the optical absorption of undoped rutile-phase bulk TiO 2 was calculated and compared to the experimental results. The estimated theoretical value of rutile TiO 2 sample was 3.0 eV. This theoretical result shows good agreement when compared with the experimental data of undoped TiO 2 sol-gel films, as well as the undoped TiO 2 film prepared by sputtering.