Far-field subdiffraction optical microscopy using metamaterial crystals: Theory and simulations

Alessandro Salandrino and Nader Engheta

Phys. Rev. B 74, 075103 – Published 15 August 2006

Abstract

Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal’s output surface with a compressed angular spectrum, resulting in a “magnified” image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed.

Received 26 May 2006

DOI:https://doi.org/10.1103/PhysRevB.74.075103

Authors & Affiliations

Alessandro Salandrino and Nader Engheta^*

Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA

^*To whom correspondence should be addressed. Email address: engheta@ee.upenn.edu

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Issue

Vol. 74, Iss. 7 — 15 August 2006

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Images

Figure 1
(Color online) Structure of the metamaterial crystal. In the inset the various parameters are shown.Reuse & Permissions
Figure 2
(Color online) Sketch of the “nonmagnifying” setup.Reuse & Permissions
Figure 3
(Color online) Sketch of the idea of the “magnifying setup” with an oblique cut.Reuse & Permissions
Figure 4
(Color online) Finite-element-method simulations of a 2D lossless (left panel) and a lossy (right panel) anisotropic crystal with an oblique cut are shown. The distribution of the magnitude of the complex magnetic field of a 2D transverse magnetic (TM) excitation is shown here. The parameters of the anisotropic medium are given in the text. The simulated two “sources” at the input plane, and their images at the output plane, which are more separated, are clearly seen. The effects of the material loss in broadening and in attenuation of the rays are evident in the right panel, where the ratio of the source amplitudes is 1:2.1.Reuse & Permissions
Figure 5
(Color online) Finite-element-method simulation of 2D cylindrical geometry, with two sources with subwavelength separation. The distribution of the magnitude of the complex magnetic field of a 2D transverse magnetic (TM) excitation is shown. Here, to show the principle of operation of the curved structure, we have an ideal lossless configuration where the permittivities of the layers are 2 and $- 2$ . With a proper design of these layers, the “spots” at the output surface can be separated with a distance larger than a necessary resolution of a conventional optical microscope. Thus, the entire system can act as a scanless optical microscope with beyond-diffraction-limit resolution.Reuse & Permissions
Figure 6
(Color online) Finite-element-method simulation of a 2D cylindrical layered structure with some realistic materials for these layers. The distribution of the magnitude of the complex magnetic field of a 2D transverse magnetic (TM) excitation is shown in the top panel. The operating wavelength is assumed to be $410 nm$ . The inner radius is $λ ∕ 4$ and the radius of the output face is $5 λ ∕ 4$ . The thickness of the layers is $λ ∕ 32$ . The materials used for layers are silver (dielectric constant $- 5.08 + i 0.226$ at $410 nm$ ) and diamond (dielectric constant 5.08). The middle panel shows the normalized input power as a function of the angle at the input face. The bottom panel shows the output power as a function of the angle at the output face. The structure shows a magnification of a factor 5, therefore allowing us to resolve in far zone details down to $λ ∕ 10$ .Reuse & Permissions

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