Improvement of the optical transmission of polymer planar waveguides by plasma treatment
Résumé
The aim of the present work is to reduce the optical losses of glycidyl ether of bisphenol A (SU-8) polymer planar waveguides using cold plasmas, which allow the substitution of H atoms by F. CF4 and mixtures of CF4/H2 RF plasma treatments were carried out for the surface fluorination of the SU-8 waveguide. The observed decrease in the optical losses due to propagation in the Si/SiO2/fluorinated SU-8 planar waveguides has been correlated with the surface fluorination as measured by XPS and CA measurements. In order to understand and to optimize the fluorination process, the plasma phase was analyzed by OES. Finally, the thickness of the fluorinated layer was estimated using modulated incident-angle XPS.