Modified RCWA method for studying the resonance diffraction phenomena on metal gratings

Abstract

In this work, using the numerical analysis of the diffraction TM-polarized optical waves by metal gratings under resonance of the electromagnetic field was presented. Modified RCWA method has been proposed. Notably, Toeplitz matrices were modified in the system of differential equations. These matrices are formed on base of complex series of the periodic function of grating's dielectric permittivity and its inverse function. In fact, a rectangular function of permittivity was changed by trapezium function. However grating's relief remains rectangular. Proposed change of the dielectric permittivity function more exactly corresponds to actual gratings. Better convergence of calculation results for the modified system of equations was determined. Modified RCWA was tested for several gratings in order to illustrate the provided advantages.