Fluorine plasma treatment on SU-8 polymer for integrated optics

The authors present a study of the influence of fluorine plasma treatment on SU-8 polymer waveguides and investigate the property changes including optical losses due to propagation, selectivity on the polarisation modes, and so on. As cogent results, these techniques based on radiofrequency fluorine plasma treatment (CF4) modified strongly the abovementioned properties. First, the optical losses ascribed to Si/SiO2/fluorinated SU-8 microstructures have been evaluated to 1.25 dB/cm for TE00 polarisation, and then have been reduced by 0.11 dB/cm, compared to propagation in pure SU-8. Moreover, such a particular plasma treatment leads to a substantial selectivity on optical polarisation states regarding the TM00 optical mode which has been advantageously used. Thereby, integrated optical polarizers have been achieved on fluorinated SU-8.