98%
921
2 minutes
20
Recently, significant efforts have been devoted to guaranteeing high-quality communication services in fast-moving scenes, such as high-speed trains. The challenges lie in the Doppler effect that shifts the frequency of the transmitted signal. To this end, the recent emergence of spatiotemporal metasurfaces offers a promising solution, which can manipulate electromagnetic waves in time and space domain while being lightweight and cost-effective. Here we introduce deep learning-assisted spatiotemporal metasurfaces to automatically and adaptively neutralize Doppler effect in fast-moving situations. A tandem neural network is used to establish a rapid connection between on-site targets and time-varying series of spatiotemporal metasurfaces, endowing the capability of on-demand beamforming with Doppler effects offset. Moreover, oblique incidence problems are also studied in practice, which can be used for relieving multipath effect. In the microwave experiment, we fabricate the intelligent spatiotemporal metasurfaces and demonstrate the potential to fulfill Doppler-offset beamforming under oblique incidence.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11636439 | PMC |
http://dx.doi.org/10.1515/nanoph-2023-0569 | DOI Listing |
Light Sci Appl
August 2025
School of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
Electro-optic active metasurfaces have attracted attention due to their ability to electronically control optical wavefronts with unprecedented spatiotemporal resolutions. In most studies, such devices require gate arrays composed of a large number of independently-controllable local gate electrodes that address the local scattering response of individual metaatoms. Although this approach in principle enables arbitrary wavefront control, the complicated driving mechanism and low optical efficiency have been hindering its practical applications.
View Article and Find Full Text PDFNatl Sci Rev
September 2025
School of Electronic Engineering, Xidian University, Xi'an 710071, China.
The increasing demand for public safety has created an urgent need for high-performance technologies capable of detecting hazardous liquids with high accuracy, efficiency, and cost-effectiveness. Conventional liquid detection methods often fall short in addressing these requirements due to limitations in precision, operational complexity, and scalability. This study introduces a wireless intelligent system for the detection of suspicious liquids, leveraging advancements in programmable metasurface and software defined radio technologies.
View Article and Find Full Text PDFThis study aims to investigate dispersion engineering mechanisms within unilateral and bilateral metasurface-based leaky-wave antennas, presenting methodologies focused on space-time modulation of impedance boundary conditions. Utilizing the generalized framework based on the Floquet-wave expansion method, the research precisely investigates the effect of periodic space-time modulation on the dispersion characteristics of the leaky-wave antenna. The beam scanning mechanism has been investigated in the momentum and frequency domains.
View Article and Find Full Text PDFWe report spatiotemporally tunable mode coupling between Fabry-Pérot (F-P) resonances and dark or bright modes in the weak- or strong-coupling regime in an all-dielectric coupled system, which consists of an F-P microcavity formed by two distributed Bragg reflectors (DBR) and a metasurface made of periodic nanocavities. Simulation results show that F-P resonances can be tuned to be coupled to dark waveguide modes or a bright electric dipole Mie surface lattice resonance, depending on the microcavity height, and that the coupling strength can be manipulated between the weak- and strong-coupling regimes by varying the photon lifetime, or equivalently the quality factors (-factors) of F-P resonances, which can be realized by changing the number of DBR layers. We also show that the slow-light effect associated with the electromagnetically induced reflection-like window in the weak-coupling regime can also be regulated through the -factor.
View Article and Find Full Text PDFSci Adv
August 2025
Shandong Provincial Key Laboratory of Optics and Photonic Devices, Center of Light Manipulation and Applications, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
Achieving circularly polarized thermal emissions with high spatiotemporal coherence using planar structures has long been considered to be elusive. Here, we use nonlocal metasurfaces with monoclinic lattices that break mirror symmetry to efficiently achieve circularly polarized thermal emissions with both high temporal and spatial coherence. We design a chiral metasurface based on waveguide arrays with periodically shifted segments that have a saddle-shaped chiral and high- dispersion band.
View Article and Find Full Text PDF