Strong and Omnidirectional Light Absorption from Ultraviolet to Near‐Infrared Using GST Metasurface

Abstract

For the perfect light absorber, it has been a huge challenge to simultaneously realize ultra‐broadband and strong absorption of unpolarized light over a large angular range, though various materials and designs have been tried. The emergence of optical metasurface with powerful light field regulation ability provides a promising new strategy for achieving perfect absorbers. Here, a Ge2Sb2Te5 (GST)‐based metasurface with an average 92.5%/94.7% (experiment/simulation) absorptivity of unpolarized light, covering an ultra‐broadband from ultraviolet to near‐infrared region is designed and demonstrated. This GST‐based metasurface consists of double‐layer GST interspaced by SiO2 layer, and both field localizations in the top patterned GST layer and intrinsic loss of the bottom patternless GST layer together contribute to this broadband absorption over wide incident angles up to 70°. Strong absorbing ability, large angular responses, and feasibly scalable fabrication for such a perfect GST‐based metasurface absorber offer more promising application opportunities in integrated optoelectronic devices.

Review of Broadband Metamaterial Absorbers: From Principles, Design Strategies, and Tunable Properties to Functional Applications

“…Phase Change Materials: In recent years, the incorporation of phase change materials represented by VO 2 , [401,[414][415] Ge 2 Sb 2 Te 5 (GST) in BMAs is a major class of design approaches as well. [416,417] As shown in Figure 8g, it is a thermally tunable BMA with VO 2 combined with ITO. [401] Figure 8h,i show that the suggested device could maintain high optical transparency while having high absorption in the microwave range.…”

“…[416] In addition, high broadband absorption has been achieved based on GST in the omnidirectional range from UV to near IR. [417] Examples of the tunable nature of such phase change materials are described in detail for the reader later (Section 4.2).…”

A TM polarization absorber based on a graphene–silver asymmetrical grating structure for near-infrared frequencies

“…Plasmonic perfect absorbers (PPAs) with narrowband and broadband absorption have been present in metamaterials since they were first investigated in 2008. 1,2 A large number of PPAs have been proposed for frequencies ranging from visible, 3 near-infrared, 4,5 mid-infrared, 6 and terahertz 7 to microwave. 8 PPAs have attracted a large amount of research attention due to their potential applications in sensors, 9 solar cells, 10 thermal imaging devices, 11 and photodetectors.…”

Mid-infrared pyroelectric detector with metasurface electrode for broadband enhanced absorption

“…In other words, the enhanced absorption and detection only occur at a relatively narrow wavelength band. Only for the purpose of broadband absorption without integration into the PPD architecture, various schemes are also demonstrated including the composite meta-units with different dimensions or geometries that are arranged in vertical [25,26] or parallel [25,27,28] direction, the integration of all-dielectric or all-metal metasurface [29][30][31], the integration of multiple plasmonic resonance or multipole resonance [32][33][34][35][36] and the multipolar interference [37,38]. However, most of those schemes are intrinsically incompatible with PPD structures or too complex for compact device integration.…”