Broadband metamaterials absorbers with high absorption, ultrathin thickness and easy configurations are in great demand for many potential applications. In this paper, we first analyse the coupling resonances in a Ti/Ge/Ti three-layer absorber, which can realise broadband absorption from 8 to 12 μm. Then we experimentally demonstrate two types of absorbers based on the Ti/Ge/Si₃N₄/Ti configuration. By taking advantage of coupling surface plasmon resonances and intrinsic absorption of lossy material Si₃N₄, the average absorptions of two types of absorbers achieve almost 95% from 8 to 14 μm (experiment result: 78% from 6.5 to 13.5 μm). In order to expand the absorption bandwidth, we further propose two Ti/Si/SiO₂/Ti absorbers which can absorb 92% and 87% of ultra-broadband light in the 14–30 μm and 8–30 μm spectral range, respectively. Our findings establish general and systematic strategies for guiding the design of metamaterial absorbers with excellent broadband absorption and pave the way for enhancing the optical performance in applications of infrared thermal emitters, imaging and photodetectors.

具有高吸收、超薄厚度和易于配置的宽带超材料吸收器在许多潜在应用中都有很大的需求。在本文中，我们首先分析了 Ti/Ge/Ti 三层吸收器中的耦合共振，该吸收器可以实现 8 到 12 μm 的宽带吸收。然后我们通过实验证明了基于 Ti/Ge/Si ₃ N ₄ /Ti 配置的两种类型的吸收剂。通过利用耦合表面等离子体共振和有损耗材料Si ₃ N _{4 的}固有吸收，两种类型的吸收体的平均吸收率在8至14 μm范围内几乎达到95%（实验结果：6.5至13.5 μm范围内为78%）。为了扩大吸收带宽，我们进一步提出了两个 Ti/Si/SiO ₂/Ti 吸收剂可分别吸收 14-30 μm 和 8-30 μm 光谱范围内 92% 和 87% 的超宽带光。我们的研究结果为指导具有优异宽带吸收的超材料吸收器的设计建立了通用和系统的策略，并为提高红外热发射器、成像和光电探测器应用中的光学性能铺平了道路。