Sub-Diffraction Limitted Imaging with a Spatially Dispersive Slab

Avner Yanai Applied Physics, The Hebrew University of Jerusalem, Jerusalem, Israel Uriel Levy Applied Physics, The Hebrew University of Jerusalem, Jerusalem, Israel

In 2000, it was suggested that a thin planar metallic slab can perform as a lens capable of producing an image with sub-diffraction limited (SDL) resolution [1]. In this seminal paper, Pendry showed that by using a thin metallic slab, only few tens of nanometers thick, which is excited with light near its surface plasmon (SP) resonance frequency, an image with SDL size can be obtained, due to the high momentum frequency components of the SP modes that are supported by the interfaces between the metallic slab and the dielectric medium surrounding it. This imaging concept was coined as the “poor man’s lens” and was the subject of debate in the scientific community over the years. Here, we propose a different physical concept for achieving SDL imaging, taking advantage of the longitudinal modes within a thin metallic slab that is described by the hydrodynamic model. The SDL imaging occurs for discrete frequencies satisfying ω>ω­p. This frequency regime is different from the original proposal of the “poor man’s lens”, in which the incident illumination frequency is in the vicinity of the SP resonance frequency ω­p/√2. Furthermore, the underlying physical mechanism of the two approaches is different. In the original proposal, the high-k components of the source are reconstructed at the image plane due to that the SP resonance surface modes which support high spatial frequency components. In contrast, our approach is not based on surface modes. Instead, the high-k components are transferred to the image plane by the longitudinal modes, which typically have propagation constants more than an order of magnitude larger than the vacuum propagation constant k0=2π/λ0. The permittivity of the slab is described by the hydrodynamic model [2,3].

[1] J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000).

[2] C. David, N.A. Mortensen, and J. Christensen, Sci. Rep. 3, 2526 (2013).

[3] P. J. Feibelman, Prog. Surf. Sci. 12, 287–408 (1982).

ulevy@mail.huji.ac.il









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