In this study, we designed a novel ultra-wideband (UWB) absorber and numerically analyzed it to demonstrate that its light absorptivity was greater than 90% in the wavelength range of visible light and near-infrared (405-1505 nm). The structure of proposed novel UWB absorber consisted of four layers of films, including silica, titanium, magnesium fluoride, and aluminium, and the upper silica and titanium layers had rectangular cubes in them. For that, the excitations of propagating surface plasmon resonance (PSPR), local surface plasmon resonance (LSPR), and the resonance of Fabry-Perot (FP) cavity were generated at the same time and combined to reach the effect of perfect absorption and ultra-wideband. The proposed absorber had an average absorptivity of 95.14% in the wavelength range of 405 ∼ 1505 nm when the light was under normal incidence. In addition, the UWB absorber was large incident angle insensitive and polarization-independent. The absorber proposed in the paper had great prospects in the fields of thermal electronic equipment, solar power generation, and perfect cloaking.

The research of metamaterial shows great potential in the field of solar energy harvesting. In the past decade, the design of broadband solar metamaterial absorber (SMA) has attracted a surge of interest. The conventional design typically requires brute‐force optimizations with a huge sampling space of structure parameters. Very recently, deep learning (DL) has provided a promising way in metamaterial design, but its application on SMA development is barely reported due to the complicated features of broadband spectrum. Here, this work develops the DL model based on metamaterial spectrum transformer (MST) for the powerful design of high‐performance SMAs. The MST divides the optical spectrum of metamaterial into N patches, which overcomes the severe problem of overfitting in traditional DL and boosts the learning capability significantly. A flexible design tool based on free customer definition is developed to facilitate the real‐time on‐demand design of metamaterials with various optical functions. The scheme is applied to the design and fabrication of SMAs with graded‐refractive‐index nanostructures. They demonstrate the high average absorptance of 94% in a broad solar spectrum and exhibit exceptional advantages over many state‐of‐the‐art counterparts. The outdoor testing implies the high‐efficiency energy collection of about 1061 kW h m⁻² from solar radiation annually. This work paves a way for the rapid smart design of SMA, and will also provide a real‐time developing tool for many other metamaterials and metadevices.

We theoretically proposed and numerically analyzed a polarization-independent, wide-angle, and ultra-broadband absorber based on a multi-layer metasurface. The numerical simulation results showed that the average absorption rates were more than 97.2% covering the broad wavelength of 400~6000 nm (from visible light to mid-infrared light) and an absorption peak was 99.99%, whatever the polarization angle was changed from 0° to 90°. Also, as the incidence angle was swept from 0° to 55°, the absorption performance had no apparent change over the wavelength ranges of 400 to 6000 nm. We proved that the proposed metasurface structure was obviously advantageous to achieve impedance matching between the absorber and the free space as compared with conventionally continuous planar-film structures. The broadband and high absorption resulted from the strong localized surface plasmon resonance and superposition of resonant frequencies. As expectable the proposed absorber structure will hold great potential in plasmonic light harvesting, photodetector applications, thermal emitters and infrared cloaking.

The selective broadband absorption of solar radiation plays a crucial role in applying solar energy. However, despite being a decade‐old technology, the rapid and precise designs of selective absorbers spanning from the solar spectrum to the infrared region remain a significant challenge. This work develops a high‐performance design paradigm that combines deep learning and multi‐objective double annealing algorithms to optimize multilayer nanostructures for maximizing solar spectral absorption and minimum infrared radiation. Based on deep learning design, we experimentally fabricate the designed absorber and demonstrate its photothermal effect under sunlight. The absorber exhibits exceptional absorption in the solar spectrum (calculated/measured = 0.98/0.94) and low average emissivity in the infrared region (calculated/measured = 0.08/0.19). This absorber has the potential to result in annual energy savings of up to 1743 kW h/m ² in areas with abundant solar radiation resources. Our study opens a powerful design method to study solar‐thermal energy harvesting and manipulation, which will facilitate for their broad applications in other engineering applications.

Dielectric metasurfaces typically have much lower terahertz (THz) optical losses than metallic metasurfaces and have attracted great attention in boosting trace sensing of THz molecular fingerprints. Previous studies usually neglect the losses of dielectric materials in their ideal physical models, and lack of experimental validation. Despite the low extinction coefficient of dielectric materials in metastructures, their optical losses cannot be neglected in practice, especially when their thicknesses are much larger than those of trace samples. This would hinder the retrieval of trace THz molecular fingerprints. In this work, we fabricate the THz dielectric metasurface of lossy silicon with a gold mirror and demonstrate its angle-multiplexed fingerprint metasensing scheme based on a series of guided mode resonances. We investigate the physical mechanism of silicon optical loss and mirror reflection. We discover that the use of a gold mirror in the lossy Si metastructure plays a critical role in boosting broadband THz fingerprint detection. Our method dramatically enhances the metasensing performance of the THz trace fingerprint, and the maximum enhancement is up to 98 times compared with conventional approaches. This article provides a powerful guide for the experimental study of trace THz fingerprint metasensing, which will inspire more THz trace sensing applications.