Optimisation of transmission properties and subwavelength imaging of silver-dielectric layered structures operating in the canalization regime

Abstract

We analyse the subwavelength imaging properties of a flat lens consisting of alternating thin metal and dielectric layers operating in the canalization regime. We show that the skin depth of the homogenised structure may exceed by almost two orders of magnitude the skin depth of silver. Its optimisation leads to the choice of the optimal wavelength of 437 nm. In effect, the multilayer exhibits high transmission combined with subwavelength resolution at distances of several wavelengths. We show how the Fabry-Perot resonant conditions for the thickness of the structure become relaxed for thicker multilayers. Our simulations are based on the transfer and scattering matrix methods, valid for calculating either evanescent or propagating modes.