Spatial Frequency Characterisation of a Far-Field Superlens to Facilitate General Purpose Imaging

摘要

Based on subwavelength energy concentration and enhancement of evanescent fields, far-field superlenses (FSLs) were proposed recently as a means to achieve super-resolution imaging and thus improve the accuracy and resolution of optical microscopy. Comprised of a thin-film plasmonic enhancement layer and a diffraction grating, the performance of FSLs depends greatly on the geometry and size of its constituent parts. In this paper, we aim to characterize the resolution capabilities of FSLs in a novel and meaningful way, while also exploring the effects of non-ideal grating geometries due to fabrication limitations on imaging performance. We use finite element modelling to explore trapezoidal, inverse-trapezoidal, circular, rounded rectangular, and rectangular grating profiles and present a transfer function that quantifies the performance of these grating profiles in terms of their transmission at different wavenumbers.