Near-field probes using double and single negative media

Abstract

Evanescent probe imaging is a powerful characterization technique with subwavelength resolution. In this paper, we present a theoretical and numerical study of the effect of using double negative (DNG) and single negative (SNG) metamaterials in evanescent probe imaging. A sensitivity definition is introduced for evanescent probes and it is shown using quantitative measures that the sensitivity can be increased using DNG material for a target in vacuum and for a buried target. A minimum DNG thickness is required to achieve an improvement in the sensitivity. For a buried target, there is a fundamental limitation on the maximum achievable sensitivity, in addition to a limitation due to the loss of DNG materials. SNG metamaterials have similar improvements over the sensitivity as the DNG materials but there are additional limitations due to the different transmission characteristics of SNG media. To validate the theoretical findings, numerical simulations are presented.