Creation of strongly localized and strongly enhanced optical near-field on metallic probe-tip with surface plasmon polaritons.

A practical technique by which a strongly confined and strongly enhanced optical near-field can be created on a metallic probe-tip is investigated. The technique uses an I-shaped aperture in a pyramidal structure formed on a thick metallic screen. The pyramidal structure divided into two sections by the I-shaped aperture and one of them is used as a tapered metallic probe. A surface plasmon polariton (SPP), which is excited and enhanced in the I-shaped aperture, propagates along the side surface of the aperture and pyramidal structure and illuminate the probe-tip. Scattering of optical waves by this structure is solved numerically using a volume integral equation by a generalized minimum residual method and fast Fourier transformation. It is shown that a strongly localized and strongly enhanced optical field is created at the tip of this metallic probe by SPPs. The fundamental characteristics of the localized and enhanced optical near-field on the probe-tip are investigated.