# An Optically Transparent Metasurface for Microwave Amplitude-Phase Manipulation
## 4 Conclusions  
In conclusion, a new type of multifunctional metasurface simultaneously possessing high visible transparency and microwave amplitude-phase manipulation was proposed. A metal frame with ultra-narrow linewidth was adopted to construct the anisotropic resonator, whereas the reflective backplane of the meta-atom was replaced by metallic meshes, facilitating high visible light transmittance of 63.7% at 400-800 nm. In terms of the microwave frequencies, based on in-plane rotation and geometric size variation, continuous amplitude modulation covering a range of 0-0.9 and eight-level phase gradient with a \(\pi/4\) interval was enabled at 16 GHz. Utilizing the fascinating capability of independently manipulating the amplitude and phase, a spatially multiplexed meta-hologram capable of reconstructing two holographic images in distinct imaging planes was experimentally demonstrated, showing good agreement with the numerical simulations. We believe our proposed metasurface provides a robust and generalized path towards realizing the compatibility between visible and microwave bands, which is required for future smart windows, wireless communications, and data storage systems.  
Conceptualization, [PERSON] and J.G.; methodology, H.X. and J.G.; software, H.X. and J.G.; validation, J.G. and Y.Z.; investigation, H.X., J.G. and Y.Z.; resources, X.J.; writing--original draft preparation, H.X. and J.G.; writing--review and editing, X.J. and C.Z.; visualization, X.J.; supervision, C.Z., H.D. and L.Z.; project administration, H.D. and L.Z.; funding acquisition, H.D. and L.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (12374297, 12404487), Hangzhou Science and Technology Bureau of Zhejiang Province (TD2020002), the Postdoctoral Fellowship Program (Grade C) of the China Postdoctoral Science Foundation (GZC20241815), the Natural Science Foundation of Shanghai (23 ZR1471500, 24 ZR1474400), the Shanghai Sailing Program (23 YF1453900), and the Academic/Technology Research Leader Program of Shanghai (23 XD1404500).  
Not applicable.  
The data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.  
The authors declare no conflicts of interest.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & \multirow{2}{*}{**Material**} & **Center** & **Manipulation** & **Function** & **Optical** \\  & & **Frequency** & **Approach** & **Function** & **Transparency** \\ \hline [28] & Metal & 11.1 GHz & Amplitude–phase & Beamforming & None \\ [29] & Metal & 28 GHz & Amplitude–phase & OAM generation & None \\ [30] & Metal & 13 GHz & Amplitude–phase & Airy beam generation & None \\ [31] & Metal & 13 GHz & Amplitude–phase & OAM generation & None \\ [46] & ITO & 24.5/41 GHz & Phase & Hologram & 46\% \\ [47] & ITO & 20 GHz & Phase & OAM generation & Yes \\ This work & Metal frame & 16 GHz & Amplitude–phase & Hologram & 63.7\% \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of the proposed metasurface and its counterparts.