The sensitivity of composite bimodal waveguide SU-8

This paper presents the results of measurements of the refractive index and thickness of the waveguide layer SU-8. The mode sensitivity has been calculated as a function of the thickness in a bimodal structure. The dierential interference was analyzed concerning modes of the same types TE0TE1 and TM0TM1 and modes of the same order (TE₀TM₀, TE ₁-TM₁). The thickness of the layer was determined when the interferometer is most sensitive to changes of the refractive index. It has been proved that the sensitivity of the structure can be increased by adding a nanometric layer with a high refraction index (nA = 1:975) on the waveguide layer.