Modeling of Plasmon Resonances of Multiple Flat Noble-Metal Nanostrips With a Median-Line Integral Equation Technique

The surface plasmon and the periodicity-induced resonances in the scattering and absorption of light by multiple flat nanosize noble-metal strips are investigated using a new efficient model. It exploits the fact that the nanostrip thickness is a small fraction of the wavelength in the visible range. This justifies shrinking the strip cross section to its median line and using the generalized boundary conditions on that line, with the strip thickness entering the coefficients. As a result, the scattering problem is reduced to the singular and hypersingular integral equations. We discretize them using quadrature formulas of interpolation type and build an algorithm having guaranteed convergence and controlled accuracy of computations. It enables fast simulation of structures consisting of many noble-metal strips. Near- and far-field characteristics for finite flat grating of silver and gold nanostrips are presented.