Two-dimensional point spread matrix of layered metal-dielectric imaging elements

TL;DR

This paper investigates how layered metal-dielectric lenses alter the polarization state during 2D imaging, revealing matrix transfer functions and cross-polarization effects, and demonstrates a nanoelement design for beam separation.

Contribution

It introduces a matrix-based point spread function to analyze polarization effects in layered metal-dielectric imaging and designs a nanoelement for beam separation.

Findings

Polarization is not preserved due to differential transfer functions for TM and TE modes.

The point spread function can be represented as a matrix to characterize resolution.

A nanoelement with radial slits effectively separates non-diffracting beams.

Abstract

We describe the change of the spatial distribution of the state of polarisation occurring during two-dimensional imaging through a multilayer and in particular through a layered metallic flat lens. Linear or circular polarisation of incident light is not preserved due to the difference in the amplitude transfer functions for the TM and TE polarisations. In effect, the transfer function and the point spread function that characterize 2D imaging through a multilayer both have a matrix form and cross-polarisation coupling is observed for spatially modulated beams with a linear or circular incident polarisation. The point spread function in a matrix form is used to characterise the resolution of the superlens for different polarisation states. We demonstrate how the 2D PSF may be used to design a simple diffractive nanoelement consisting of two radial slits. The structure assures the separation of non-diffracting radial beams originating from two slits in the mask and exhibits an interesting property of a backward power flow in between the two rings.