Sub-wavelength imaging at optical frequencies using canalization regime

TL;DR

This paper demonstrates sub-wavelength optical imaging using a layered metal-dielectric structure operating in the canalization regime, achieving resolutions of λ/20 and predicting λ/60 with different materials.

Contribution

It introduces a new lens design that operates in the canalization regime, avoiding negative refraction and allowing larger lens sizes compared to previous sub-wavelength lenses.

Findings

Achieved λ/20 resolution at 600 nm with a 300 nm thick structure.

Predicted λ/60 resolution with a similar structure using different materials.

Lens thickness can be an integer multiple of half-wavelengths, enabling larger lenses.

Abstract

Imaging with sub-wavelength resolution using a lens formed by periodic metal-dielectric layered structure is demonstrated. The lens operates in canalization regime as a transmission device and it does not involve negative refraction and amplification of evanescent modes. The thickness of the lens have to be an integer number of half-wavelengths and can be made as large as required for ceratin applications, in contrast to the other sub-wavelength lenses formed by metallic slabs which have to be much smaller than the wavelength. Resolution of $\lambda/20$ at 600 nm wavelength is confirmed by numerical simulation for a 300 nm thick structure formed by a periodic stack of 10 nm layers of glass with $\epsilon=2$ and 5 nm layers of metal-dielectric composite with $\epsilon=-1$. Resolution of $\lambda/60$ is predicted for a structure with same thickness, period and operating frequency, but formed by 7.76 nm layers of silicon with $\epsilon=15$ and 7.24 nm layers of silver with $\epsilon=-14$.