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With rapid development of holography, metasurface-based holographic communication scheme shows great potential in development of adaptive electromagnetic function. However, conventional passive metasurfaces are severely limited by poor reconfigurability, which makes it difficult to achieve wavefront manipulations in real time. Here, we propose a holographic communication strategy that on-demand target information is firstly acquired and encoded via a depth camera integrated with modified YOLOv5s target detection algorithm, then transmitted by software defined radio modules with long term evolution at 5 GHz, and finally reproduced in the form of holographic images by spin-decoupled programmable coding metasurfaces at 12 GHz after decoding through modified Gerchberg–Saxton algorithm. Experiments are conducted to demonstrate the brand-new concept of optical information conversion to electromagnetic one via above intelligent scheme. Our strategy may open a novel avenue toward applications of near-field communication based on adaptive variation of electric field patterns (i.e. holographic images).

Camouflage is an important technology in various scenarios. Usually, this involves the visible compatibility of the background, which however is facile under infrared thermal radiation detection. The simultaneous visible and thermal camouflage are challenging because it requires full and decoupled manipulations of visible reflection and infrared emissivity using one single device, let alone to its adaptivity to complex environments. Here, we report a programmable, colored thermal camouflage at 3–5 μm and 8–14 μm based on mode coupling in phase-change In3SbTe2 materials. A series of industry-friendly colored multilayer thermal emitters are designed consisting of an anti-reflectance layer for structure coloration above a coupled nanocavity for IR modulation, which easily realizes the complete decoupled control of visible color and infrared emissivity. Our solution features independent structural visible colors in the full visible range and continuously programmable dual-band emissivity modulation with up to 90 % absolute tuning range. Our work facilitates near optimal camouflage and anti-counterfeiting solution for visible-infrared multi-band compatibility of complex environments under different temperatures and colored appearances.

Achieving independent control of phase and amplitude is pivotal yet challenging for electromagnetic (EM) wave manipulation. Metasurface provides an efficient recipe to this challenge, but most of the work reports so far are still confined in half space (transmission or reflection) and manipulation of linearly polarized EM waves, restricting itself from integrating more functionalities with complex wavefronts into one optoelectronic device. Here, a hybrid phase approach synthesizing propagation and geometric phases is proposed to achieve independent and arbitrary control of amplitude and phase response for circularly polarized (CP) wave in full space by using a non‐interleaved single‐celled metasurface. To validate the concept, a full‐space dual‐channel meta‐hologram is experimentally demonstrated, manifesting images of letters "T" and "R" at lower and upper frequencies (f1 and f2), respectively. The finding of full‐space metasurface opens new possibilities to control CP waves by simultaneous amplitude and phase modulations, which is important for high‐capacity wireless communications, as well as sophisticated functionality, and other advanced meta‐devices. [ABSTRACT FROM AUTHOR]

Metasurface radome is crucial to protect the radiating antenna and control electromagnetic waves flexibly. However, current design methods for metasurface radome merely focus on the single propagation direction, with limited degrees of freedom. Here, a super radome is proposed with a directional scattering response based on Janus metasurface that can realize the phase modulation of y‐polarized waves and the amplitude modulation of x‐polarized waves with a judiciously designed structure. Both numerical and experimental results illustrate two cross‐polarized transmission windows with intensity exceeding 0.9 centered at 10 and 12.2 GHz and two out‐of‐band invisibility with considerable backward radar cross‐section reduction over −10 dB within 9.3–15.4 and 7.5–23.8 GHz when the radome is illuminated by y‐ and x‐polarized waves along negative and positive z directions, respectively. Moreover, the radar cross‐section reduction is maintained for off‐normal incidence even up to 45°. This method sets up a directional degree of freedom for advanced radome design and demonstrates its enormous potential in developing next‐generation stealth antennas. [ABSTRACT FROM AUTHOR]

Camouflage is an important technology in various scenarios. Usually, this involves the visible compatibility of the background, which however is facile under infrared thermal radiation detection. The simultaneous visible and thermal camouflage are challenging because it requires full and decoupled manipulations of visible reflection and infrared emissivity using one single device, let alone to its adaptivity to complex environments. Here, we report a programmable, colored thermal camouflage at 3–5 μm and 8–14 μm based on mode coupling in phase-change In3SbTe2 materials. A series of industry-friendly colored multilayer thermal emitters are designed consisting of an anti-reflectance layer for structure coloration above a coupled nanocavity for IR modulation, which easily realizes the complete decoupled control of visible color and infrared emissivity. Our solution features independent structural visible colors in the full visible range and continuously programmable dual-band emissivity modulation with up to 90 % absolute tuning range. Our work facilitates near optimal camouflage and anti-counterfeiting solution for visible-infrared multi-band compatibility of complex environments under different temperatures and colored appearances. [ABSTRACT FROM AUTHOR]

Skin effect in electromagnetism describes the tendency of alternating current to predominantly flow near the surface rather than through the center of a conductor. Here, another skin effect of electromagnetic flux is reported to occur in non‐conductive materials, specifically within 3D anisotropic zero‐index metamaterials, as well as its potential application in subwavelength wave manipulation. It is found that when a medium of near‐zero longitudinal permittivity and permeability is embedded with inclusions whose transverse permittivity and/or permeability approach zero, the electromagnetic flux therein is directed and extremely compressed beneath the surfaces of inclusions within a skin depth less than λ0/150. This unusual effect empowers arbitrary control of electromagnetic flux at deep subwavelength scale. Customized subwavelength pathways for electromagnetic flux are demonstrated in full‐wave simulations via practical implementations. The study opens a new avenue for extreme confinement and flexible control of electromagnetic flux at deep‐subwavelength scale. [ABSTRACT FROM AUTHOR]

Generating multiple beams in distinct polarization states is promising in multi-mode wireless communication but still remains challenging in metasurface design. Here, we theoretically and experimentally demonstrate a concept of broadband receiving-transmitting metasurface and its application to the generation of multi-polarization multi-beam. By employing U-slot patch, an efficient receiving-transmitting element with full phase coverage is designed within a wide bandwidth. Based on this architecture, a methodology is proposed to generate dual spin-decoupled beams and then developed into the strategy of generating multiple beams at different linear polarizations. To verify our strategy, two lens antennas, respectively radiating dual-spin dual-beam and quad-polarization quad-beam, are devised. With multi-polarization multi-beam radiated, the two lens antennas are both with whole aperture efficiency above 40% within the bandwidth of 10.6-12.3 GHz (14.8%), firmly validating our strategy and design.

Optical materials capable of dynamically manipulating electromagnetic waves are an emerging field in memories, optical modulators, and thermal management. Recently, their multispectral design preliminarily attracts much attention, aiming to enhance their efficiency and integration of functionalities. However, the multispectral manipulation based on these materials is challenging due to their ubiquitous wavelength dependence restricting their capacity to narrow wavelengths. In this article, we cascade multiple tunable optical cavities with selective-transparent layers, enabling a universal approach to overcoming wavelength dependence and establishing a multispectral platform with highly integrated functions. Based on it, we demonstrate the multispectral (ranging from 400 nm to 3 cm), fast response speed (0.9 s), and reversible manipulation based on a typical phase change material, vanadium dioxide. Our platform involves tandem VO 2 -based Fabry-Pérot (F-P) cavities enabling the customization of optical responses at target bands independently. It can achieve broadband color-changing capacity in the visible region (a shift of ~60 nm in resonant wavelength) and is capable of freely switching between three typical optical models (transmittance, reflectance, and absorptance) in the infrared to microwave regions with drastic amplitude tunability exceeding 0.7. This work represents a state-of-art advance in multispectral optics and material science, providing a critical approach for expanding the multispectral manipulation ability of optical systems., (© 2024. The Author(s).)