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arXiv · 2107.04990

Optical Brewster metasurfaces exhibiting ultra-broadband reflectionless absorption and extreme angular-asymmetry

Huiying Fan·Jensen Li·Yun Lai·Jie Luo
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Abstract

Impedance mismatch between free space and absorptive materials is a fundamental issue plaguing the pursue of high-efficiency light absorption. In this work, we design and numerically demonstrate a type of non-resonant impedance-matched optical metasurfaces exhibiting ultra-broadband reflectionless absorption based on anomalous Brewster effect, which are donated as optical Brewster metasurfaces here. Interestingly, such Brewster metasurfaces exhibit a unique type of extreme angular-asymmetry: a transition between perfect transparency and perfect absorption appears when the sign of the incident angle is changed. Such a remarkable phenomenon originates in the coexistence of traditional and anomalous Brewster effects. Guidelines of material selection based on an effective-medium description and strategies such as the integration of a metal back-reflector or folded metasurfaces are proposed to improve the absorption performance. Finally, a gradient optical Brewster metasurface exhibiting ultra-broadband and near-omnidirectional reflectionless absorption is demonstrated. Such high-efficiency asymmetric optical metasurfaces may find applications in optoelectrical and thermal devices like photodetectors, thermal emitters and photovoltaics.

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Huiying Fan, Jensen Li, Yun Lai, Jie Luo. 2021-07-11. Optical Brewster metasurfaces exhibiting ultra-broadband reflectionless absorption and extreme angular-asymmetry. https://arxiv.org/abs/2107.04990

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