Wide-angle polarization independent infrared broadband absorbers based on metallic multi-sized disk arrays

Cheng-Wen Cheng,Kun-Ting Lai,Min-Hsiung Shih,Yia-Chung Chang,Mohammed Nadhim Abbas,Chao-Wei Chiu

doi:10.1364/oe.20.010376

Abstract

Two-dimensional metallic broadband absorbers on a SiO(2)/Ag/Si substrate were experimentally studied. The absorptivity of such structure can be increased by tailoring the ratio of disk size to the unit cell area. The metallic disk exhibits a localized surface plasmon polariton (LSPP) mode for both TE and TM polarizations. A broadband thermal emitter can be realized because the LSPP mode is independent of the periodicities. By manipulating the ratios and disk sizes, a high-performance, wide-angle, polarization-independent dual band absorber was experimentally achieved. The results demonstrated a substantial flexibility in absorber designs for applications in thermal photovoltaics, sensors, and camouflage.

Highlights

Localized surface plasmon polaritons (LSPPs) are electromagnetic excitations localized at the metal/dielectric interface with a strong field enhancement and a decay of evanescent wave intensity away from the boundary
Two-dimensional metallic broadband absorbers on a SiO2/Ag/Si substrate were experimentally studied. The absorptivity of such structure can be increased by tailoring the ratio of disk size to the unit cell area
A broadband thermal emitter can be realized because the LSPP mode is independent of the periodicities

Summary

Introduction

Localized surface plasmon polaritons (LSPPs) are electromagnetic excitations localized at the metal/dielectric interface with a strong field enhancement and a decay of evanescent wave intensity away from the boundary. One of the important applications of LSPPs is in plasmonic absorbers with a large absorption from the field enhancement near the interface. A round-shaped metal disk absorber is applied because it can provide an angle and polarization independent LSPP band over a broad range of incidence angles of up to nearly 90° [5, 20]. We first experimentally found that the absorptivity of the round-shaped disk absorber obeying the Beer Lambert law can be enhanced by increasing the ratio of disk size to the unit cell area. By modifying the area filling ratio, we can demonstrate a highperformance, wide-angle, polarization-independent dual band absorber with two maximal absorptivity peaks greater than 84% over a wide range of incident angles

Methods

Results

Conclusion