Transparency and super-resolution in metal-dielectric layered structures

A carefully designed metal-dielectric periodic stack forms a simple optical metamaterial with small losses and super-resolving properties for imaging between its external boundaries in the near-UV or visible wavelength range. The effective penetration depth reaches the order of one micrometer with the resolution even tenfold better than predicted by the Rayleigh criterion in air. Therefore the stack may be seen as a transparent and super-resolving metamaterial. Depending on the strength of Fabry-Perot resonances it may either support standing-wave internal field distributions or allow for approximately diffraction-free propagation not limited to any specific beam profiles. The latter case enables to design shaped elements such as prisms, or elements of optical cloaks which retain the same diffraction-free properties. Here an overview of the physical models which explain the super-resolution is presented - in particular with reference to the effective medium theory. The numerical simulations are based on the transfer matrix method. A discussion on the analogies between subwavelenegth imaging with metal-dielectric multilayers and isoplanatic imaging systems considered in the past within the framework Fourier Optics is included.