Sliding metasurface for wide-angle beam steering with sharp frequency filtering

Modern electromagnetic systems are becoming increasingly crowded in both spectral and spatial domains. Future wireless communication, sensing, and electromagnetic front-end systems require compact devices that can both select desired frequency bands and direct electromagnetic waves toward desired spatial channels. Conventional metasurfaces have shown powerful capabilities in beam steering and wavefront shaping. However, dynamic beam steering usually relies on active components and complex biasing circuits, while sharp frequency filtering is often realized by separate frequency-selective structures. As a result, it remains challenging to integrate high-performance spectral filtering and wide-angle spatial beam control within a compact and fully passive platform.

 

In a new paper published in Light: Science & Applications, a team of scientists led by Professor Weiren Zhu from Shanghai Jiao Tong University, China, and Professor Guangwei Hu from Nanyang Technological University, Singapore, developed a fully passive sliding metasurface that unifies sharp frequency filtering and wide-angle beam steering within a single architecture. The proposed metasurface establishes a two-dimensional frequency-angle selection window, allowing electromagnetic waves to be selected and controlled according to both their frequency and propagation direction. In the demonstrated microwave implementation, the device achieves sharp spectral selectivity, strong out-of-band suppression, and stable beam steering over a wide angular range, providing a compact route to coordinated frequency-angle wave control.

 

The key concept of this work is to replace local phase reconfiguration with global geometric displacement. Instead of using active elements to tune the phase of each meta-atom, the proposed metasurface consists of two complementary phase profiles that can slide laterally with respect to each other. This relative displacement produces a controlled translation of the spectral centroid in reciprocal space, thereby steering the transmitted beam continuously. Since the steering mechanism is governed by the spatial relationship between two phase surfaces rather than by frequency-specific electrical tuning, the strategy reduces the need for active components and external driving circuits, while suggesting potential extensibility to other frequency regimes.

 

For the demonstrated microwave implementation, a transmission-line-inspired meta-atom design is adopted to integrate frequency selectivity and phase control within the same physical aperture. In this design, the stacked layers are reused to construct a high-order filtering response for sharp frequency selection and an embedded quasi–Fabry–Pérot cavity for phase control. This co-design allows the metasurface to perform spectral filtering and beam steering simultaneously, rather than treating them as independent functions implemented by separate devices.

 

By constructing a passive multidimensional transfer function, the sliding metasurface provides a new approach to electromagnetic wave manipulation in complex environments. The ability to discriminate waves in both frequency and angle is particularly relevant to interference suppression, spectral-spatial multiplexing, electromagnetic front ends, and future wireless systems, where unwanted signals may differ from desired signals in either spectral or angular coordinates. This work therefore expands the design space of passive metasurfaces and offers a promising platform for compact, energy-efficient, and multidomain electromagnetic systems.

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