Metasurface Design and Wavefront Control

Metasurfaces are ultrathin assemblies of subwavelength scatterers engineered to impose abrupt phase, amplitude and polarisation changes on incident waves. By sculpting the spatial arrangement and geometry of the constituent meta-atoms, designers can achieve bespoke wavefront transformations such as anomalous refraction, focusing, beam steering and holography within a planar footprint. Key advances in design methodologies include the introduction of phase-gradient metasurfaces, Huygens’ metasurfaces that balance electric and magnetic responses, and the emergence of metagratings that exploit discrete diffraction orders for near-unity efficiency. Materials range from high-index dielectrics to plasmonic metals, with trade-offs between bandwidth, scattering losses and fabrication complexity. Recent trends focus on large-angle performance, broadband achromatic operation and actively reconfigurable platforms, extending applications across compact optical imaging, secure communications, sensing and next-generation wireless networks.

Research from Nature Portfolio

Recent studies have demonstrated low-index, low-aspect-ratio grating designs capable of redirecting and focusing visible light at large off-axis angles with near-unity efficiency. By adopting scalable nano-imprint lithography and tailoring subwavelength metagrating profiles, these flat optics achieve fields of view exceeding 110° without resorting to high-index semiconductor nanostructures. In another development, reflective blazed surfaces with multiple coupled resonances per unit cell form blazing passbands that broaden both operational bandwidth and angular tolerance. Experiments at microwave frequencies confirm that these multi-pole resonant metagratings can sustain zero specular scattering over a wide frequency band, suggesting routes to high-efficiency retroreflectors, spectral beam combiners and frequency-scanned antenna reflectors.

Metasurface Design and Wavefront Control publication trend

The graph below shows the total number of articles in metasurface design and wavefront control across all publications each year (not limited to Nature Index journals).

Technical terms

Metasurface: An engineered planar array of subwavelength scatterers that imposes designed discontinuities in the phase, amplitude or polarisation of incident waves.

Metagrating: A periodic or locally periodic arrangement of scatterers that leverages discrete diffraction orders to achieve near-unitary wavefront manipulation without continuous impedance gradients.

Phase discontinuity: An abrupt change in the optical phase imparted at a surface, enabling control over the propagation direction of transmitted or reflected waves.

Huygens’ metasurface: A class of metasurfaces combining orthogonal electric and magnetic responses in each meta-atom to independently tailor amplitude and phase of scattered waves.

Diffraction efficiency: The fraction of incident optical power steered into a desired diffraction order by a metasurface or metagrating.

References

1. Off-axis metasurfaces for folded flat optics. Nature Communications (2023).
2. Reconfigurable Tri‐Mode Metasurface for Broadband Low Observation, Wide‐Range Tracing, and Backscatter Communication. Advanced Science (2024).
3. Broadband depolarized perfect Littrow diffraction with multilayer freeform metagratings. Optica (2023).
4. Wave-front Transformation with Gradient Metasurfaces. Physical Review X (2016).
5. Optical Huygens’ Metasurfaces with Independent Control of the Magnitude and Phase of the Local Reflection Coefficients. Physical Review X (2014).
6. Flat Engineered Multichannel Reflectors. Physical Review X (2017).
7. Wide-band/angle Blazed Surfaces using Multiple Coupled Blazing Resonances. Scientific Reports (2017).
8. Metagratings for Efficient Wavefront Manipulation. IEEE Photonics Journal (2021).
9. Wide-angled off-axis achromatic metasurfaces for visible light.. Optics Express (2016).