A suggestion of utilizing bimodal layers of the polymer SU8 for the purpose of monitoring the changes in the refractive index

The paper presents the results of investigations concerning the measurements of the refractive index and the thickness of planar waveguide structures, obtained by photopolymerization 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 has been analyzed, concerning the modes of the same types TE ₀-TE ₁ and TM ₀-TM ₁. The thickness of the layer has been determined when the interferometer is most sensitive to the changes in the refractive index.