Significance The emission emitted by traditional thermal emission sources usually manifests as broadband, unpolarized, and nearly isotropic incoherent light. This makes it difficult to flexibly regulate the properties of infrared thermal emission, thereby limiting its applications in the infrared field.
In recent years, with the rapid development of nanophotonics research and micro-nano processing technology, metasurfaces have been widely used in the regulation of thermal emission properties, effectively breaking through the bottlenecks faced by traditional thermal emission regulation. At present, thermal emission devices developed based on metasurfaces have been widely applied in fields such as thermal management, energy utilization, and sensing detection, significantly promoting the development of various infrared applications. In addition, relying on diversely designed metasurface structures, researchers have achieved multi-degree-of-freedom regulation of thermal emission-including its spectrum, polarization, and angle.
Progress With the continuous development of metasurfaces, thermal emission devices have been widely applied in thermal management, energy utilization, sensing and detection. In terms of thermal management, Rephaeli et al. first proposed a radiative cooling scheme based on a metal-dielectric photonic structure. The research groups of TAO Guangming and MA Yaoguang jointly designed and fabricated an optical radiative cooling fabric with a morphologically hierarchical structure to achieve efficient outdoor personal thermal management. In the field of energy utilization, CHANG C C et al. experimentally demonstrated a Solar Thermophotovoltaic (STPV) system. A metasurface was fabricated using high-melting-point tungsten, which maintains stability even at a high temperature of 1200 ℃. The team of HENRY A reported a Thermophotovoltaic (TPV) cell with an efficiency exceeding 40%. ZHOU L et al. proposed a plasmon-enhanced solar desalination device. For sensing and detection applications, XU et al. developed a sapphire (Al2O3)-based mid-infrared hybrid nanofluid-Surface-Enhanced Infrared Absorption (SEIRA) platform for liquid sensing. BARHO et al. proposed a surface-enhanced spectroscopy technique based on thermal emission from Ⅲ-Ⅴ semiconductor metasurfaces, enabling effective detection of molecular layers coated on the metasurface. Furthermore, with the continuous advancement of metasurfaces, simultaneous multi-parameter regulation of thermal emission properties—such as spectrum, polarization, and angle—has been achieved. In terms of thermal emission spectrum regulation: The research group of Padilla W J combined different "cross"-shaped metal structures and used a metasurface with a Metal-Dielectric-Metal (MIM) configuration to experimentally realize single-wavelength and dual-wavelength thermal emission. COPPENS et al. integrated an MIM metasurface with zinc oxide (ZnO), a photosensitive material; ultraviolet light iremission excites free carriers in ZnO, thereby regulating the optical properties of the metasurface. In thermal emission polarization regulation: LIU B A et al. designed an asymmetric nano-antenna structure. NGUYEN et al. proposed an ultra-thin chiral metasurface based on connected zigzag resonators, achieving broadband circularly polarized mid-infrared thermal emission. The JACOB Z team, by simultaneously breaking mirror symmetry and spatial inversion symmetry, used a symmetry-broken "F"-shaped metasurface to realize asymmetric circularly polarized thermal emission in the mid-wave infrared. In thermal emission angle regulation: ZHANG et al. designed an aluminum/silicon dioxide/aluminum metasurface structure, achieving multi-degree-of-freedom regulation of the spectrum, polarization, and angle of phonon thermal emission using its internal mode coupling mechanism. ZHANG et al. further proposed a Fano resonance-based thermal radiator with an aluminum/silicon nitride/aluminum sandwich structure. ZHONG et al. directly characterized the dispersion properties of a superlattice structure using Angle-Resolved Thermal Emission Spectroscopy (ARTES), verifying the existence of exceptional points in non-Hermitian systems. ZHONG et al. combined the concept of topological interface states with thermal emission regulation, designing a superlattice unit based on a "gold-germanium-(gold)-germanium" structure. To achieve multi-wavelength, multi-mode emission output and multi-degree-of-freedom thermal emission regulation, the concept of a thermal emission microchip was proposed. ZHANG et al. studied multiple symmetry-protected BICs in one-dimensional and two-dimensional synthetic parameter spaces based on a thermal emission microchip formed by a nano-pore metasurface array. CHU et al. proposed and realized a multi-wavelength thermal emission microchip with high spatial resolution; based on this chip, CHU et al. further proposed a compact and integrated indirect infrared absorption spectroscopy detection method.
Conclusions and Prospects In recent years, the technology for regulating infrared thermal emission based on metasurfaces has made continuous progress and has been widely applied in various fields such as thermal management, energy utilization, sensing and detection, and infrared light sources. Expanding the thermal emission regulation mechanism and realizing the collaborative optimization of multiple parameters based on metasurfaces not only promotes the in-depth development of theories and technologies related to thermal emission regulation, but also lays a solid foundation for the innovation and expansion of relevant applications.To further promote the research on thermal emission regulation to the field of practical applications, there are still many tasks worth carrying out in the future. For instance, improving the Q-factor of thermal emission devices, enhancing the precision of micro-nano processing technology, utilizing artificial intelligence for inverse structural design, realizing dynamic regulation of thermal emission devices, and integrating special physical mechanisms from optical research fields (such as topological photonics, moiré photonics, and non-Hermitian photonics) with thermal emission regulation mechanisms into metasurface design.
DownLoad: