Far-field imaging by a planar lens: Diffraction versus superresolution

[摘要] We resolve the long-standing controversy regarding far-field imaging by a planar lens made of a left-handed medium and demonstrate theoretically that the far-field image has a fundamentally different origin depending on the relationship between losses inside the lens and the wavelength of the light, lambda. At small enough lambda, the image is always governed by diffraction theory, and the resolution is independent of the absorption if both Im epsilon < 1 and Im mu < 1. For any finite lambda, however, a critical absorption exists below which the superresolution regime occurs, although this absorption is extremely low and can hardly be achieved. We demonstrate that the transition between the diffraction-limited and superresolution regimes is governed by a universal parameter combining absorption, wavelength, and lens thickness. Finally, we show that this parameter is related to the resonant excitation of surface plasma waves.

[发布日期] 2007-11-01

[关键词] LEFT-HANDED MATERIAL;PERFECT-LENS;PHOTONIC CRYSTAL;NEAR-FIELD;SUPERLENS;SLAB;PERMITTIVITY;PERMEABILITY;LIMITATIONS;POLARITONS