Xun Cao

Metasurfaces enable precise manipulation of multiple degrees of freedom of electromagnetic waves, yet few existing studies achieve manipulation of multiple polarization modes of electromagnetic waves across the full space. Reconfigurable metasurfaces have recently emerged as a research focus for achieving multi‐channel manipulation of electromagnetic waves due to their flexible active tuning capabilities. Inspired by the concept of bound states in the continuum (BIC), strong electromagnetic responses can be excited in metasurfaces through the introduction of structural asymmetry. This paper presents a general and straightforward design strategy for a reconfigurable quasi‐BIC metasurface, which leverages the quasi‐BIC mechanism to induce linear dichroism in the transmission channel and to generate circular dichroism in the reflection channel. By leveraging the reversible insulator‐metal‐transition (IMT) of vanadium dioxide (VO ₂ ), dynamic switching of terahertz waves between transmission and reflection channels under two distinct polarization modes is achieved. Experimental results agree well with simulation, validating the effective multi‐channel terahertz manipulation using the proposed reconfigurable metasurface. This metasurface holds potential for applications in terahertz wireless communication, holographic imaging, and information encryption.

Multispectral detection technologies spanning optical and thermal bands pose a severe threat to military camouflage while simultaneously unlocking new opportunities for covert communication. However, smart materials capable of both countering these threats and exploiting these bands for communication are still lacking. Here, using a Bayesian-optimization-based inverse-design strategy, we propose an opto-thermally decoupled photonic structure. It features broadband optical camouflage across the 0.38–2.5 μm range, encompassing the visible, near-infrared, and short-wave infrared bands (including the 1.55 μm laser wavelength), with a tunable structural-color palette that covers 66% of the CMYK gamut. Crucially, while these colors are independently tunable, the structure modulates radiance in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) bands for dynamic thermal camouflage, achieving consistent MWIR/LWIR emissivity switching between 0.41 ± 0.04/0.90 ± 0.01 and 0.93 ± 0.03/0.45 ± 0.01 driven by the vanadium dioxide (VO₂) phase transition. Beyond camouflage, by precisely regulating the temperature, we exploit the differential MWIR/LWIR thermal signatures generated by the continuous phase evolution of VO₂ to encode information for infrared encrypted communication. We experimentally demonstrate the structure’s dual capabilities for broadband opto-thermal concealment and covert communication. This work integrates multispectral camouflage and covert communication within a single platform, offering a new design strategy for next-generation military smart materials.

The optical tunability of electrochromic smart windows enables heat regulation, providing a viable route to reduced building energy consumption. Reversible electrodeposition‐based systems are advantageous due to the high optical contrast. However, they are often limited by high specular reflectance, insufficient modulation in the near‐infrared (NIR) region, and a lack of continuously tunable intermediate states. Therefore, we introduced a redox‐mediated strategy that leverages the synergistic interaction between Mn ²⁺ and viologens to regulate the MnO ₂ deposition kinetics. This cooperative interaction ensures precise optical tunability, enabling the stabilization of continuous intermediate states while simultaneously enhancing NIR modulation in the colored state. The device achieves an ultralow average visible transmittance of 0.1%, a solar modulation efficiency Δ T _sol of 63.3%, low reflectance (∼ 8%) and a coloration time of 10.5 s. This smart window significantly reduces energy demands for building thermal management, lowers carbon emissions, and provides a viable pathway toward energy‐efficient green buildings.

The promising prospects for all‐day building thermal management are driving widespread research into spectrally selective manipulation materials. This article first summarizes the evolution path of metal reversible deposition technology, noting its advantages of cost‐effectiveness and scientific rigor. It then highlights the groundbreaking work by Wang et al. (published in ACS Energy Letters , 2025, 10, 3231) on coupling metastructured photothermal conversion electrodes and reversible Cu deposition for all‐day energy management. Finally, the commercial viability of Wang et al.'s approach for building energy saving and its potential applicability to other scenarios are elaborated.

Camouflage technology has garnered increasing attention for various applications. With the continuous advancement of detection technologies and the increasing variability of camouflage scenarios, the demand for multispectral dynamic camouflage has been steadily growing. In this work, we present a multispectral dynamic regulator based on phase-changing material vanadium dioxide (VO₂) that can be dynamically and functional-independently regulated for reflective color and thermal radiation. It has been shown that the device can achieve a wide color gamut variation in visible band while simultaneously achieving highest emissivity tunability (Δε=-0.58) in the atmospheric window up to now, achieves multispectral camouflage spanning the visible and infrared spectra among VO₂-based devices. To go a step further, we advance the device featuring long-term cycling stability to achieve thermal-electric dual-mode response and flexibility for a series real-world camouflage performance evaluation. We have also demonstrated the digital camouflage based on multispectral dynamic regulator through Neighboring Color Block Camouflage Algorithm, highlighting its potential for practical implementation in different camouflage scenarios. The device achieves multispectral dynamic camouflage, opening a path for advancing the technology development in both the scientific field and practical applications.

Tri-band modulation combines temperature adaptation and mechanical response, guiding thermal radiation via structured deflection directions.

The manipulation of thermal radiation amplitude or direction over a broadband spectrum is a fundamental capability, demonstrating significant potential in thermal management and infrared information encryption. However, existing approaches cannot control both aspects simultaneously. In this study, an ultrabroadband directional tunable thermal emitter (UDTTE) utilizing the metal‐insulator transition properties of vanadium dioxide photonic structure and the Brewster effect is proposed. Before the phase transition, the UDTTE exhibits an average emissivity as low as 0.07 across the 3–20 µm band and the entire range of angles. After the phase transition, the UDTTE maintains a low emissivity of 0.33 for incident angles below 73° but displays a high emissivity of 0.78 in the 73°–83° range. This designed experiments in information encryption demonstrate that the UDTTE can synergistically utilize temperature, viewing angle, and polarization to achieve multi‐level encryption of IR information. This strategy further enhances the capability to manipulate thermal radiation and holds promise for advancing technologies in information security, IR camouflage, and thermal management.

The application of reversible electrodeposition electrochromic technology in the field of smart windows shows great potential for effective management of sunlight and heat by controlling the color and transparency changes of materials through electric fields. However, despite the significant progress in optical modulation amplitude, energy efficiency, and easy preparation of large area devices, the technology still faces some challenges, such as susceptibility to side reactions, absence of an intermediate state, and inability to modulate visible to infrared light independently. In this paper, we look forward to the future development of reversible electrodeposition electrochromic smart windows, and propose that by rationally selecting solvents and endowing the devices with bistable and intermediate states, it is expected to improve its practicability further, and thereby promoting the wide application of electrochromic smart windows in sustainable development.

Temperature is a key manifestation of energy, with about 51% of global energy consumption occurring in the form of heat annually