Comparison of imaging with sub-wavelength resolution in the canalization and resonant tunnelling regimes

TL;DR

This paper compares sub-wavelength imaging capabilities of metal-dielectric multilayers in canalization and resonant tunnelling regimes, analyzing their transfer functions, PSFs, and effects of material losses using simulations.

Contribution

It provides a detailed comparison of imaging properties in two regimes, highlighting how losses and propagation affect resolution and PSF shape.

Findings

Point Spread Functions are approximately Gaussian in canalization regime

Material losses suppress higher resonance transmission but do not reduce resolution

PSF width can be reduced by free space propagation

Abstract

We compare the properties of subwavelength imaging in the visible wavelength range for metal-dielectric multilayers operating in the canalization and the resonant tunnelling regimes. The analysis is based on the transfer matrix method and time domain simulations. We show that Point Spread Functions for the first two resonances in the canalization regime are approximately Gaussian in shape. Material losses suppress transmission for higher resonances, regularise the PSF but do not compromise the resolution. In the resonant tunnelling regime, the MTF may dramatically vary in their phase dependence. Resulting PSF may have a sub-wavelength thickness as well as may be broad with multiple maxima and a rapid phase modulation. We show that the width of PSF may be reduced by further propagation in free space, and we provide arguments to explain this surprising observation.