MEASUREMENT OF RADIATION TRANSFER THROUGH NANO-APERTURES USING NEAR-FIELD SCANNING OPTICAL MICROSCOPY

摘要

Ridge apertures in various shapes have attracted extensive studies which showed their potential capabilities in realizing both enhanced transmission and nanoscale optical resolution, therefore, enabling ultrahigh density near-field optical recording. In this work, the optical near field distributions of an H-shaped ridge aperture and comparable regular apertures made in aluminum film are experimentally investigated using a home-made near-field scanning optical microscope. With a sub-100 nm aperture probe, the full-width half-magnitude (FWHM) near-field spot of the H aperture is measured as 106 nm by 80 nm, comparable to the gap size but substantially smaller than that obtained from a square aperture with the same area. The elongated near-field light spot in the direction across the ridges is due to the scattering of the transmitted light on the edges based on results of numerical calculations.