OPTICAL-PROPERTIES OF DIAMOND-LIKE FILMS DEPOSITED BY LASER ABLATION

Diamond-like carbon films containing less than 1 at% hydrogen have been prepared by laser ablation at different laser power densities. Optical constants such as the refraction index n, the extinction coefficient k, and the absorption coefficient alpha have been determined for photon energies between 1.5 and 5.0 eV from measurements of reflectance and transmittance. These quantities show a considerable variation with photon energy. The optical gap of the diamond-like films has been estimated to be between 1.3 and 1.8 eV. Transmission data of coated infra-red optical materials in the 2.5-15 mum range are presented which indicate the importance of diamond-like carbon films for optical applications.