Simulation of novel tip-probe providing high intensity and small spot size with a small background light in nano-optics

A novel metallic tip-probe that gives high optical intensity and small spot size with a small background light is proposed and simulated. The proposed tip-probe provides advantages of both the aperture probe and the apertureless probe currently used in the scanning near-field optical microscope. The tip-probe is illuminated by surface plasmon polaritons transmitted through the I-shaped aperture in a pyramidal structure on a thick metallic screen. Scattering of optical waves by this structure is solved numerically using a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. The proposed tip-probe is shown to simultaneously provide both high near-field intensity and small spot size with a small background light.