Determination of thickness and dielectric constant of thin films by dual-wavelength light beaming effect of a metal nanoslit

摘要

We report simultaneous determination of the thickness and dielectric constant of thin films by dual-wavelength (488 and 645 nm) light beaming effect of a metal nanoslit in an optically thick metal film flanked by periodic corrugations. The feasibility of the method is confirmed by the finite-difference time-domain simulations, and sensitivities of 72°/RIU (RIU, Refractive Index Unit) at 488 nm and 32° /RIU at 645 nm are obtained, respectively. The unambiguous determination of the thickness and dielectric constant of the samples by just one-step measurement as well as the compact optical geometry of the structures suggests a highly portable and robust novel sensing technology.