Terahertz Metasurfaces for Wavefront Manipulation

Terahertz metasurfaces are planar assemblies of subwavelength elements engineered to impose tailored amplitude, phase and polarisation on incident electromagnetic waves in the terahertz band (0.1–10 THz). By arranging arrays of meta-atoms with spatially varying geometry or material composition, these surfaces encode abrupt phase discontinuities across a wavefront, enabling beam steering, flat-optics lensing, holography and orbital angular momentum generation within an ultrathin profile. Dielectric resonators offer low absorption and broadband operation, while active platforms incorporating liquid crystal elastomers, phase-change materials or two-dimensional conductors impart dynamic control over transmitted or reflected wavefronts. Such metasurfaces overcome the size and weight limitations of conventional terahertz optics, opening avenues for compact imaging systems, wireless communication links, non-invasive sensing and on-chip photonic circuits. Recent advances have focused on broadband multi-focus lenses, programmable beam-forming architectures and reconfigurable intelligent surfaces capable of rapid modulation across wide angular and spectral ranges. The integration of stimuli-responsive materials and digital coding strategies has further propelled the practical realisation of agile terahertz devices for real-time applications.

Research from Nature Portfolio

Seminal work demonstrated an ultrathin transmission metasurface lens capable of simultaneously focusing terahertz radiation into multiple spots across a broad frequency range. This multi-focus design employed amplitude-phase retrieval algorithms to engineer phase profiles at each meta-atom, resulting in high diffraction efficiency and clear imaging at frequencies spanning 0.3–1.1 THz. The low-cost, planar geometry and broadband operation of this lens set a foundation for multi-channel terahertz imaging and signal separation in compact optical systems.

Research from all publishers

Recent developments have harnessed soft mechanical actuation and liquid crystal elastomers to achieve wide-angle beam steering with a single metasurface. By applying infrared light or thermal stimuli, these platforms alter substrate shape and local refractive index, enabling continuous and broadband deflection up to 22° at 0.68 THz, alongside tunable splitting and frequency-modulation functionalities desired for wireless communication and imaging. In parallel, multi-bit reflective surfaces based on liquid crystals have realised programmable phase shifts up to 270° around 0.28 THz, allowing dynamic control of beam angle, multiplicity and width for advanced terahertz links. Finally, GaN-based array-of-subarrays architectures under digital coding sequences have delivered real-time reconfiguration of terahertz wavefronts at 0.34 THz, demonstrating precise wide-angle scanning, multi-beam generation and diffuse scattering with switching speeds up to 100 MHz over a 70 GHz bandwidth.

Terahertz Metasurfaces for Wavefront Manipulation publication trend

The graph below shows the total number of articles in terahertz metasurfaces for wavefront manipulation across all publications each year (not limited to Nature Index journals).

Technical terms

Metasurface: A planar arrangement of subwavelength resonators engineered to control electromagnetic amplitude, phase or polarisation.

Meta-atom: An individual subwavelength element within a metasurface, designed to impart a specific phase or amplitude shift.

Phase discontinuity: An abrupt change in the phase profile of a wavefront introduced by a metasurface at the interface of adjacent meta-atoms.

Terahertz band: The region of the electromagnetic spectrum between microwave and infrared frequencies, nominally from 0.1 THz to 10 THz.

Liquid crystal elastomer: A polymer material combining liquid crystal ordering and elastic deformation, enabling shape change under optical or thermal stimuli.

Reconfigurable intelligent surface (RIS): A dynamic metasurface platform that programme-ably modulates electromagnetic waves via electronic or optical control.

Digital coding sequence: A binary or multi-level control scheme applied to meta-atoms to achieve programmable wavefront patterns.

References

1. A broadband terahertz ultrathin multi-focus lens. Scientific Reports (2016).
2. Active terahertz beam steering based on mechanical deformation of liquid crystal elastomer metasurface. Light: Science & Applications (2023).
3. A liquid crystal-based multi-bit terahertz reconfigurable intelligent surface. APL Photonics (2024).
4. Real-time programmable metasurface for terahertz multifunctional wave front engineering. Light: Science & Applications (2023).