Light Coupling Performance Analysis Between SU-8 Channel Waveguides and Gold Nanostructures

This work presents an optical analysis focused on enhancing the light coupling performance between optical channel waveguides and gold periodic nanoarrays in the visible spectrum. The proposed approach uses an indium tin oxide (ITO) thin film as buffer layer. The assessment includes the evaluation of coupling efficiency, out-of-plane scattering as well as far-field projected beam focus and diffraction angle. Finite-Difference Time-Domain (FDTD) method and scattering theory are used to investigate different nanoarray patterns. The incorporation of the ITO layer leads to an increase in coupling efficiency, an enhancement of light scattered out of the array plane and consequent improvements in the intensity peaks of the diffracted beam radiation. These improvements are met without compromising the beam’s focus or altering its deflection angle. This configuration enables a cost-effective and simple solution to enhance the performance for scattering-related applications, without changing the array features. Such waveguiding structures can be efficiently used to fabricate simple and cost effective integrated optic devices working in a wide frequency spectrum for optical communication and sensing systems.