Fabrication and Study of Planar Waveguide Based on SU-8 Polymer using Different Substrates

In this work, the planar waveguides are investigated by depositing a SU-8 polymer on PET and quartz substrates. Maxwell equations are solved for the designed waveguides to obtain the characteristic equations. By solving these equations, the minimum thickness of SU-8 necessary for operation as a waveguide is found. Afterward, the waveguides are fabricated and characterized by profilometry and UV-Vis-IR spectroscopy. It is observed that SU-8 polymer shows suitable optical transmission. Then, the effective refractive index of the waveguide, as well as the wave propagation, is recognized by the finite element method. The results of simulations show that the total reflectance phenomenon that is required for a waveguide operation is occurring more effectively in the PET/SU-8 device than in the Quartz/SU-8 and in a waveguide configuration, it possesses better performance. Also, the flexibility and low cost of PET make it a proper candidate for substitution of the typical rigid substrate such as quartz.