Dielectric probe for scattering-type terahertz scanning near-field optical microscopy

Abstract

Dielectric material was used as the probe material for a scattering-type terahertz scanning near-field optical microscope (THz S-SNOM). It was found that the dielectric probe exhibits a strong near-field scattering signal with an amplitude comparable to that of the metallic probe. The behavior of the electric near-field around the tip was calculated using the finite-difference time-domain method, showing the field enhancement comparable to that of the metallic probe. The dielectric probe also exhibited a faster temporal response compared to the response of the metallic probe. Introduction of a non-metallic probe would enlarge the application field of the THz S-SNOM technique.