Bimodal Layers of the Polymer SU8 as Refractometer

The paper presents the results of investigations concerning measurements of the refractive index and the thickness of planar waveguide structures, obtained by photo polymerization of the polymer SU8. In the paper the mode sensitivity has been calculated as a function of the thickness in a bimodal structure. The differential interference was analyzed concerning modes of the same types TE0 –TE1 and TM0 –TM1. The thickness of the layer has been determined when the interferometer is most sensitive to changes of the refractive index of the cover.