Numerical analysis of near-infrared wave propagation characteristics in dielectric-coated parallel planar microstructural waveguides

In this paper, the properties of electromagnetic (EM) wave propagation in layered planar microstructural waveguides are investigated. Analytical and numerical results are presented on the propagation of a 1-μm EM wave in a parallel planar waveguide. Its walls are made of Au or Si, coated with a thin layer of SiO₂ and separated by a fluid. The propagation characteristics of even and odd TE and TM modes are described as a function of the coating thickness. It is shown that the propagation of TE modes exhibits a sudden shift in power flow distribution from the fluid to the coating when the coating thickness exceeds a critical value. This property may be exploited for micromachined sensor applications. TM modes do not exhibit this behaviour