Highly Tunable Cascaded Metasurfaces for Continuous Two‐Dimensional Beam Steering

Abstract

Cascaded metasurfaces can exhibit powerful dynamic light manipulation by mechanically tuning the far‐field interactions in the layers. However, in most current designs, the metasurfaces are separated by gaps smaller than a wavelength to form a total phase profile, representing the direct accumulation of the phase profiles of each layer. Such small gap sizes may not only conflict with the far‐field conditions but also pose great difficulties for practical implementations. To overcome this limitation, a design paradigm taking advantage of a ray‐tracing scheme that allows the cascaded metasurfaces to operate optimally at easily achievable gap sizes is proposed. Enabled by the relative lateral translation of two cascaded metasurfaces, a continuous two‐dimensional (2D) beam‐steering device for 1064 nm light is designed as a proof of concept. Simulation results demonstrate tuning ranges of ±45° for biaxial deflection angles within ±3.5 mm biaxial translations, while keeping the divergence of deflected light less than 0.007°. The experimental results agree well with theoretical predictions, and a uniform optical efficiency is observed. The generializeddesign paradigm can pave a way towards myriad tunable cascaded metasurface devices for various applications, including but not limited to light detection and ranging (LiDAR) and free space optical communication.

Transmissive all-dielectric metasurfaces for reconstructing terahertz holographic images via polarization-multiplexing and polarization-decoupling

“…Unlike conventional optical components, metasurfaces allow for complete and independent control of the polarization, amplitude, phase, and frequency of electromagnetic (EM) waves [4][5][6][7][8]. By carefully engineering the required phases, various wavefront applications based on metasurfaces have been demonstrated, including deflection [9], holography [10][11][12][13][14][15][16], and vortex beams [17]. Among them, terahertz metasurface-based holography (meta-holography) used to record and reconstruct wavefronts is a widely discussed research hotspot owing to the capability of conveying more information in 6G communications, 3D imaging, and high-level encryptions [18,19].…”

Dual-parameter controlled reconfigurable metasurface for enhanced terahertz beamforming via inverse design method

“…However, traditional beam control technologies, such as mechanical phased arrays and leaky−wave antenna, are constrained due to their large physical dimensions, power consumption, and structure complexities [7,8]. As an alternative, reconfigurable metasurfaces have been identified as a promising solution for THz wavefront manipulation, enabling dynamic adjustments via mechanical modifications [9][10][11] or active materials such as phase−change materials [12,13], liquid crystals [14,15], 2D materials [16,17], and semiconductors [18,19]. However, previous tuning approaches generally involve uniform operations on the entire metasurface, limiting independent control of its unit structures and diminishing the functional diversity.…”

Color coded metadevices toward programmed terahertz switching

“…Especially for terahertz waves with high-capacity communications, metasurfaces provide a potential solution to the lack of functional devices. Terahertz metasurfaces have addressed a great number of scientific and technological challenges, delivering essential assistance for boosting the development of terahertz functional devices [13][14][15][16][17][18][19] . Scalable metasurfaces with individually programmable elements, simultaneous amplitude and phase control, and gigahertzspeed reconfiguration are required to fulfill the full promise of reconfigurable features and enable sophisticated electromagnetic transformations.…”