Tuning the optical constants of PVA based films for optoelectronic applications

Thin-film samples of polyvinyl alcohol, pure and mixed with polyvinylpyrrolidone, glycerin and hydrofluoric acid are prepared. The transmittance and reflectance are measured in the ultra-violet, visible and near infrared ranges. The optical properties are determined including the refractive index, the permittivity, the singleoscillator model parameters, the ratio of the free carrier concentration to its effective mass, the loss tangent, the optical conductivity, the skin depth and the surface and volume energy-loss functions. The parameters are deduced based on the thin film model and iterative calculations. It was found that, when compared to pure PVA, adding glycerin and hydrofluoric acid to PVA/PVP films results in a strong reduction of the extinction coefficient, up to 250% with an increase in the real refractive index around the telecommunications wavelength of 1550 nm. This enhances the applicability of the fabricated polymers in different optical telecommunications. Also, the optical characteristics of the fabricated samples are compared to important optical materials such as silicon and silica to show the competitiveness of the new films in the field of integrated optics applications.