Thermal radiation control has attracted increasing attention in a wide range of field, including infrared detection, radiative cooling, thermal management, and thermal camouflage. Previously reported thermal emitters for thermal camouflage presented disadvantages of lacking either tunability or thermal stability. In this paper, we propose a tunable thermal emitter consisting of metal-insulator-metal (MIM) plasmonic metamaterial based on phase-change material Ge₂Sb₂Te₅ (GST) to realize tunable control of thermal radiation in wavelength ranges from 3 μm to 14 μm. Meanwhile, the proposed thermal emitter possesses near unity emissivity at the wavelength of 6.3 μm to increase radiation heat dissipation, maintaining the thermal stability of the system. The underlying mechanism relies on fundamental magnetic resonance and the interaction between the high-order magnetic resonance and anti-reflection resonance. When the environmental background is blackbody, the tunable emitter maintains signal reduction rates greater than 80% in middle-IR and longer-IR regions from 450 K to 800 K and from room temperature to 800 K, respectively. The dependences of thermal camouflage on crystallization fraction of GST, incident angles and polarization angles have been investigated in detail. In addition, the thermal emitter can continuously realize thermal camouflage for various background temperatures and environmental background in atmospheric window in the range of 3–5 μm.

In this paper, we propose a simple plasmonic structure based on Ge₂Sb₂Te₅ (GST) to realize tunable multiband camouflage and radiation heat dissipation. In the mid-infrared (MIR) (3–5 μm) range, the proposed structure has average emissivity of 0.18 ∼ 0.76 and can be applied in tunable thermal camouflage as the GST’s crystallization fraction increases from 0 to 1. In the 5–8 μm (safe window) range, radiation heat dissipation of the proposed structure may guarantee thermal stability of the system. In the long-infrared (8–14 μm) range, the designed emitter maintains a relatively stable and low average emissivity of 0.13 ∼ 0.19 when the crystallization fraction of GST changes from 0 to 1. In addition, due to surface lattice resonance of plasmonic metamaterial, our designed emitter can also achieve laser radar camouflage at the wavelength of 10.6 μm. We have also analyzed the dependence of the camouflage performance on the GST’s crystallization fractions, polarization angle and incident angle. Moreover, simulated thermal images demonstrate tunable thermal camouflage for various background temperatures and different ambient backgrounds in the MIR ranges.

Dielectric nanoresonantors may generate both electric and magnetic Mie resonances with low optical loss, thereby offering highly efficient paths for obtaining integrated optical devices. In this paper, we propose and design an optical filter with a high working efficiency in the mid-infrared (mid-IR) range, based on an all-dielectric metasurface composed of silicon (Si) nanodisk arrays. We numerically demonstrate that, by increasing the diameter of the Si nanodisk, the range of the proposed reflective optical filter could effectively cover a wide range of operation wavelengths, from 3.8 μm to 4.7 μm, with the reflection efficiencies reaching to almost 100%. The electromagnetic eigen-mode decomposition of the silicon nanodisk shows that the proposed optical filter is based on the excitation of the electric dipole resonance. In addition, we demonstrate that the proposed filter has other important advantages of polarization-independence and incident-angle independence, ranging from 0° to 20° at the resonance dip, which can be used in a broad range of applications, such as sensing, imaging, and energy harvesting.

In this paper, we propose a tunable infrared emitter composed of ZnS/Ge/Ag/Ge₂Sb₂Te₅/Ag films and numerically demonstrate visible-infrared compatible camouflage and radiation heat dissipation.

As communication technology is entering the 6G era, a great demand for high-performance devices operating in the terahertz (THz) band has emerged. As an important part of 6G technology, indoor communication requires multi-beam steering and tracking to serve multi-users. In this paper, we have designed a graphene metasurface that can realize multi-beam steering for directional radiations. The designed metasurface consists of graphene ribbons, dielectric spacer, and metal substrate. By designing the graphene ribbons and controlling the applied voltage on them, we have obtained single-, double-, and triple-beam steering. In addition, we have also numerically calculated the far-field distributions of the steered multi-beam with a diffraction distance of 2 m. Our design has potential applications in future indoor directional 6G communications.