Abstract
A new negative-index metamaterial (NIM) structure is proposed by designing the metallic holes of traditional double-fishnet (DF) structures from uniform sizes to several different sizes. Numerical results demonstrate that the new metamaterial, as an improved variant of the DF structure, achieved a multi-band negative refractive index across a wide range of visible frequencies from 470 THz to 540 THz, which covers the red, orange, yellow, and green regions of the visible spectra. Meanwhile, a low-profile nanostrctured absorber was obtained when one side of the perforated metal layer of this multi-band NIM was substituted with a continuous metal film with the same thickness. The absorber showed the high absorption of more than 95% at multiple frequencies of 511, 520, 523, 525, and 527 THz. The behavior of multi-frequency response effectively broadened the working bandwidth. Finally, the physical mechanism of the multi-band operating characteristics of NIM and absorber was analyzed with the distributions of current intensity at different resonant frequencies.
Highlights
Negative-index metamaterials (NIMs), as artificially structured composites, have been well-established since the appearance of the first negative-index metamaterial (NIM) in 2001.1 NIMs exhibit unprecedented properties such as negative refraction,[2] superlens withThis is an Open Access article published by World Scientific Publishing Company
Since the first development of NIMs in the microwave range, the artificial magnetism and negative refractive index of these artificial materials have been shifted from the gigahertz frequencies to optical frequencies over the past decade.[10,11,12,13,14]
The operating band of the new NIM and absorber contained more responsive frequencies compared with some previous multi-band metamaterial structures
Summary
Negative-index metamaterials (NIMs), as artificially structured composites, have been well-established since the appearance of the first NIM in 2001.1 NIMs exhibit unprecedented properties such as negative refraction,[2] superlens withThis is an Open Access article published by World Scientific Publishing Company. These characteristics often lead to a narrow operating band in the vicinity of the resonant frequency, thereby seriously impeding the effective application of NIMs. the working band of NIMs should be broadened to better embody the fascinating properties as mentioned above. More than four electromagnetic resonances occurred at a broad optical range, and the combination of these resonances could effectively widen the operating band of negative-index responses.
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