Negative Index Metamaterials with Deeply Subwavelength Structural Dimensions from Near Infrared to Visible Based on Thin
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0964-R02-04
Negative Index Metamaterials with Deeply Subwavelength Structural Dimensions from Near Infrared to Visible Based on Thin Filmsββ Vitaliy Lomakin1, Yeshaiahu Fainman1, and Gennady Shvets2 1 Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093 2 Physics, University of Texas, Austin, Austin, CA, 78712
ABSTRACT Novel two and three-dimensional negative index metamaterials (NIM), viz. metamaterial with simultaneously negative permittivity, permeability, and index of refraction, are introduced. The metamaterials comprise deeply subwavelength periodic unit cells, can be tuned to operate in the near infra-red and visible spectra, and can be manufactured using standard nanofabrication methods with compatible materials. The NIMs’ unit cell comprises an optically thin metal film sandwiched between two thin metal strips or patches residing at a small distance from the film. The cavity formed between the strips or patches supports resonances with magnetic and electric response that can be tuned to exist in overlapping frequency bands thus leading to the NIM operation. INTRODUCTION Negative index metamaterials (NIM) are composites exhibiting negative permeability, permittivity, and index of refraction simultaneously for certain frequency ranges [1-6]. NIMs can be used in a number of important potential application including perfect lenses, antennas, lasers, etc [1-6]. Typical NIMs comprise periodically arranged resonant elements supporting strong magnetic and/or electric resonances. For example, microwave and terahertz NIMs can be based on split ring resonator and wire media [2]. While a number of successful realizations of NIMs in the microwave and terahertz regimes have been reported [2], realizations of NIMs in the visible regime are more puzzling. Indeed, scaling split ring resonator based NIMs to the visible regime fails [3]. Some other suggested structures can either operate only in restricted frequency regimes [4,5] or comprise unit cells with size comparable to (half) wavelength [6-9]. However, a material can be regarded as homogenized NIMs only when its unit cell is much smaller than the wavelength to avoid high-order diffraction modes that may prevent the use of NIMs in many intended applications. Recently, several two-dimensional (2D) structures that can be tuned to operate in the near infra-red (IR) and visible spectra were presented [10-11]. In this work, we develop the ideas introduced in Ref. [11] by introducing NIM structures that (i) are tunable for operation in the entire near IR and visible spectra, (ii) comprise periodic unit cells of size much smaller than the wavelength, (iii) can be easily manufactured using conventional materials (e.g. silver or gold), and (iv) can be not only 2D but also threedimensional (3D) thus providing a root to practical NIMs. In the following we elucidate the physics of operation of the introduced structures and present supporting numerical simulations.
CONFIGURATION We consider two NIM designs
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