A
pixel-controlled programmable metasurface capable of dynamically reshaping terahertz (THz) waves could open new possibilities for compact imaging, communications and optical systems. The device functions as a
phase-type spatial terahertz modulator, combining independent pixel-level encoding with the ability to switch between multiple optical functions on a single platform.
Terahertz radiation occupies the electromagnetic spectrum between infrared and microwaves and offers properties including high resolution, non-ionizing operation and substantial channel capacity. These characteristics make THz technology attractive for applications ranging from
material characterization and sensing to high-capacity wireless communications. However, creating compact devices that can flexibly manipulate THz wavefronts remains challenging.
The new approach uses a
50 × 50 pixel array of specially designed meta-atoms incorporating
vanadium dioxide (VO₂), a phase-change material. Each meta-atom contains four VO₂ patches embedded within a metallic split-ring resonator. Patterned femtosecond laser pulses selectively activate these patches, allowing the phase response of individual pixels to be programmed. A flexible polyimide substrate helps localize the photo-induced heating and suppress thermal crosstalk between neighboring elements.
At an operating frequency of
0.7 THz, the platform employs
2-bit encoding with four programmable states spanning a full
2π phase range in approximately π/2 increments. The experimentally measured
amplitude conversion efficiency reaches 27%, demonstrating practical polarization conversion alongside programmable phase control.
Importantly, one metasurface can perform several distinct functions simply by changing the spatial pattern of the optical pump. Demonstrations include a
dynamic zoom meta-lens with switchable focal lengths of 10 and 12 mm, a
focused vortex-beam generator with tunable topological charges of +1 and −1, and
dynamic holographic imaging. The holographic capability was demonstrated by reconstructing and switching between the letters “C”, “N” and “U”.
By combining
pixel-level programmability, phase control and multifunctionality in a compact transmissive architecture, the platform provides a route toward increasingly integrated THz components. Further improvements in response speed, efficiency and optical pattern switching could strengthen its prospects for
next-generation wireless communication, high-resolution imaging and reconfigurable terahertz systems.
Keywords: metasurface, phase change material, programmable, phase-type modulator, pixel-level encoding
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Li GB, Li GY, He ZH et al. Pixel-controlled programmable metasurface as phase-type spatial terahertz modulator.
Opto-Electron Adv, 260028 (2026). DOI:
10.29026/oea.2026.260028