Multispectral measurements of slightly anisotropic thin films by guided optics method

We report quantitative evidence of the slight anisotropic behavior of several Ta2O5 dielectric thin films. Refractive indices and thickness have been determined by using the prism-film coupler setup. In order to obtain dispersion values for the refractive indices, the measurements have been realized at four different wavelengths, 632.8, 514.5, 488.0 and 457.9 nm. We have checked the results by measuring the layers with two different prisms. A new numerical approach to the problem has been useful to determine the parameters of the layers.