Tungsten based anisotropic metamaterial as an ultra-broadband absorber
We show theoretically that an array of tungsten/germanium anisotropic nano-cones placed on top of a reflective substrate can absorb light at the wavelength range from 0.3 [mu] m to 9 [mu] m with an average absorption efficiency approaching 98%. It is found that the excitation of multiple orders of s...
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Published in | Optical materials express Vol. 7; no. 2; pp. 606 - 617 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.02.2017
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Subjects | |
Online Access | Get full text |
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Summary: | We show theoretically that an array of tungsten/germanium anisotropic nano-cones placed on top of a reflective substrate can absorb light at the wavelength range from 0.3 [mu] m to 9 [mu] m with an average absorption efficiency approaching 98%. It is found that the excitation of multiple orders of slow-light resonant modes is responsible for the efficient absorption at wavelengths longer than 2 [mu] m, and the anti-reflection effect of tapered lossy material gives rise to the near perfect absorption at shorter wavelengths. The absorption spectrum suffers a small dip at around 4.2 [mu] m where the first order and second order slow-light modes get overlapped, but we can get rid of this dip if the absorption band edge at a long wavelength range is reduced down to 5 [mu] m. The parametrical study reflects that the absorption bandwidth is mainly determined by the filling ratio of tungsten as well as the bottom diameter of the nano-cones and the interaction between neighboring nano-cones is quite weak. Our proposal has some potential applications in the areas of solar energy harvesting and thermal emitters. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 2159-3930 2159-3930 |
DOI: | 10.1364/OME.7.000606 |