Information metasurfaces have attracted much attention in recent years due to the capability to link the physical world and information science. However, most of the current information metasurfaces are either phase-only coding or amplitude-only coding, limiting their functions and applications. Here, a broadband and programmable amplitude-phase-jointcoding (APJC) information metasurface is proposed and experimentally demonstrated, from which the phase and amplitude of reflected electromagnetic waves can be independently controlled by adjusting the bias voltage of PIN diode integrated in the metaatom. In particular, the reflection amplitude can be continuously controlled from 0.1 to 0.9, and the reflection phase can be switched between two states with about 180°phase difference. Thus, the proposed metasurface is capable of realizing independent 1-bit or multibit amplitude coding and 1-bit phase coding, and both of them can be reprogrammed in real time in broad band from 8 to 13 GHz. The abilities of the programmable APJC information metasurface in manipulating the electromagnetic waves are demonstrated by both numerical simulations and experiments, including to suppress the sidelobes of scattering beam, generate the diffractive waves with arbitrary magnitudes, and so on. These results show unique advantages of APJC information metasurface in real-time independent controls of energy allocation and wavefront tailoring of the electromagnetic waves in a wide frequency band.

metasurfaces have been widely employed in anomalous reflection and refraction, [11][12][13] beam manipulations, [14][15][16] and microwave imaging. [17][18][19] Generally, the EM property of metaatoms is firstly characterized by reflection or transmission coefficients to determine if the metasurface works in the reflection state or transmission state, and then the amplitude and phase distributions of the meta-atoms can be designed delicately to modulate spatially propagating waves (SPW) in multiple degrees of freedom. In 2014, the concept of coding metasurface was proposed and the distribution of meta-atoms is described by coding sequences. [20] The EM waves are manipulated by different coding sequences and can be controlled by digital devices further, which builds a bridge between the physical field and the information field, indicating potential applications in wireless communications [21][22][23] and smart devices. [24,25] In addition, surface impedance is another property to characterize the holographic metasurface, which is widely used in the design of holographic antenna. [26][27][28][29] The surface impedance of holographic metasurface is modulated periodically to radiate surface waves (SW) to leaky waves with different polarizations and directions. Similar to the reflective (or transmissive) metasurfaces with discrete phase distributions, the value of surface impedance can also be discretized and the radiative properties of the holographic antenna will be maintained, [30] which simplifies the design and fabrication process and provides a possible way for the development of reconfigurable holographic antennas.Recently, with the increasing demands for device integration and communication capacity, more and more multiplexed metasurfaces have been proposed, including the frequencymultiplexed metasurfaces, [31][32][33][34][35] polarization-multiplexed metasurfaces, [36][37][38][39] and space-multiplexed metasurfaces. [40][41][42] In addition, the multiplexed metasurface for mathematical operations and imaging processing is also widely explored, which can be a promising candidate for highly efficient analog processors to implement parallel computing tasks. [43,44] However, these multiplexed metasurfaces are either only based on phase and amplitude modulations to control SPW [31][32][33][38][39][40][41][42][43][44] or based on surface impedance modulation to control SW, [34][35][36][37] and the research on multiplexed metasurface that can control both SPW and SW simultaneously is still very limited. In 2019, we proposed aIn recent years, frequency-multiplexed metasurfaces have received extensive attention due to the increasing demands for device integration and communication capacity. However, most of previously reported works can only manipulate either surface waves (SW) or spatially propagating waves (SPW). In this paper, a frequency-multiplexed holographic-reflective-integration (HRI) coding metasurface is proposed, which can independently manipulate SW and SPW at different frequencies with a shared aperture....

Spin‐decoupled metasurfaces can realize independent phase controls of two orthogonally circularly polarized (CP) waves, and hence have attracted much attention in recent years. However, all previously reported metasurfaces capable of simultaneously manipulating the transmission and reflection of CP waves can only achieve two decoupled polarization conversion channels. In this work, a spin‐ and space‐multiplexing metasurface is proposed, that can achieve independent phase controls of four different CP conversion channels, including two cross‐polarized transmission channels and two co‐polarized reflection channels. The performance of the metasurface is experimentally validated by multi‐channel independent holographic imaging. The results show that four independent holograms are realized in four CP conversion channels by only using a single metasurface, which can greatly improve the information capacity of the metasurfaces and make full use of polarization and space resources.

Simultaneous realization of printing and holographic images has become an emerging and promising technology for optical storage and anti‐counterfeiting, which can significantly enhance the information capacity and security of an optical system. Herein, a non‐interleaved four‐channel metasurface based on opposite‐chirality‐coexisted meta‐atoms is proposed, which can simultaneously support four independent circular polarization (CP) information channels, including two near‐field printing channels and two far‐field holography channels. In addition, due to the chiral resonance properties, the operation frequencies of these four polarization channels can also be flexibly designed to simultaneously achieve polarization multiplexing and frequency multiplexing. As a proof of concept, two four‐channel metasurfaces, one of which works at a single frequency and the other works at two different frequencies, are designed and validated numerically and experimentally. It is shown in the results that two printing and two holographic images with different handedness can be stored at one frequency or two different frequencies through the flexible design of metasurface. This four‐channel metasurface provides a new avenue for the design of future photonic devices with highly integrated and multiple functionalities, and may have an advantage in diverse potential applications, such as advanced anti‐counterfeits, optical data storage, and image displays.

Polarization plays an important role in practical applications, and hence it is an essential task to generate the desired polarization of a spatial propagating wave (SPW). Here, the authors propose a method to design radiation metasurface, or metasurface emitter, which can produce arbitrarily polarized SPW. Different from the conventional transmission and reflection metasurfaces that can only manipulate the incoming spatial wave, the proposed radiation metasurface can be regarded as an electromagnetic (EM) wave emitter that can generate SPW by itself. More importantly, the polarization of the generated SPW can be flexibly customized by designing the phase distribution on metasurface. The metasurface is fed by a monopole antenna, and the energy is first coupled into the metasurface to form a surface wave. Modulated by the metasurface, the surface wave is then converted into SPW. As a proof of concept, they design and fabricate the radiation metasurfaces that are capable of generating radially, azimuthally, linearly, and circularly polarized SPWs, as well as dual‐beam radiations with different polarizations, respectively. The measured results have a good match to the theoretical predictions and full‐wave simulations. The proposed method provides an efficient way to generate SPWs with any desired polarizations for easy integration.