Simulation of confined and enhanced optical near-fields for an I-shaped aperture in a pyramidal structure on a thick metallic screen

A modification of the I-shaped aperture proposed previously by the authors—that is, an I-shaped aperture in a pyramidal structure on a thick metallic screen—is proposed and simulated. This structure is useful in the application of the I-shaped aperture to practical near-field optical systems. Scattering of optical waves by this structure in a thick metallic screen is solved numerically using a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. It is shown that this aperture structure simultaneously provides high emission intensity and small spot size through excitation of the surface plasmon polariton on the sidewalls of the aperture in the pyramid structure.