Coupling efficiency enhancement between SU-8 waveguides and plasmonic nanostructures through indium tin oxide thin films

We present an optical analysis of the light coupling between a SU-8 polymer waveguide and a nano-cylinder surface array, for biosensing applications with scattering-induced fluorescence. The coupling efficiency was studied in the 490-590 nm range using Finite Difference Time Domain (FDTD) method and scattering theory. We modeled thin films of indium tin oxide (ITO) buffer layers with different thicknesses to evaluate the behavior of the device in a sandwich configuration. We found that ITO enhances the waveguide-array coupling efficiency up to 5 times.