Sub-wavelength imaging at optical frequencies using canalization regime

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 $λ/20$ 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 $ε=2$ and 5 nm layers of metal-dielectric composite with $ε=-1$. Resolution of $λ/60$ is predicted for a structure with same thickness, period and operating frequency, but formed by 7.76 nm layers of silicon with $ε=15$ and 7.24 nm layers of silver with $ε=-14$.

4 pages, 4 figures, submitted to PRL