A spectral element method calculation of extraordinary light transmission through periodic subwavelength slits

A spectral element method together with a surface integral equation as the radiation boundary condition is used to simulate the scattering properties of periodic subwavelength slits. The surface integral equation utilizes the periodic Green's function in the wave number space and is solved by the method of moments, while the interior inhomogeneous medium is modeled by the spectral element method. The solution convergence is found to be exponential; i.e., the error decreases exponentially with the order of basis functions. To our knowledge, such a fast solver with spectral accuracy is new in the scattering problem of periodic structures. Scattering properties of a gold slit grid within the whole wavelength-incidence angle parameter space are investigated, with the confirmation that strong transmission of light through subwavelength slits is achievable. © 2010 Optical Society of America.