Plain quantification of subwavelength-gap metal-clad planar waveguides by the approximate analytical approach

A theoretical study that enables us to make a plain quantitative analysis of subwavelength-gap metal-clad planar waveguides (SMWs) via the analytical approach with a few-percentage-point discrepancy error compared to the complicated computational approach is presented. A variety of the characteristic features of SMWs, such as effective refractive index, propagating loss, mode width, and Fabry-Perot multiple-pass transmittance, have been analytically quantified by simple functions of SMW parameters, for the first time, to the best of the author's knowledge. By applying the theoretical results to various real metal SMWs, their maximum achievable nanophotonic performances have been demonstrated. (c) 2023 Optica Publishing Group