Polarization Conversion Techniques in Electromagnetic Metasurfaces

Electromagnetic metasurfaces harness subwavelength patterned elements to exert precise control over the phase, amplitude and polarization of incident waves. By engineering anisotropic or chiral unit-cell geometries, researchers have achieved transformations between linear, orthogonal linear and circular polarization states. Key mechanisms include resonant phase delays in metallic or dielectric resonators, geometric (Pancharatnam–Berry) phase manipulation and interference between complementary scatterers. Designs span reflective and transmissive layouts, from microwave to terahertz frequencies, with ultra-thin profiles often below 0.02λ0. Modern advances aim for ultra-wideband operation, wide-angle stability and dynamic tunability, enabling applications in satellite communications, remote sensing, imaging, stealth technology and radar cross section reduction.

Research from Nature Portfolio

Recent studies have demonstrated that multi-band ultrathin reflective metasurfaces can achieve both linear and circular polarisation conversion across satellite communication bands spanning Ku (13.5–18 GHz), K (18–26.5 GHz) and Ka (26.5–38.5 GHz). These metasurfaces employ bilayer designs with tailored unit-cell geometries that impart frequency-dependent phase shifts, yielding left-handed and right-handed circular polarisation in distinct sub-bands and more than 95 % linear conversion efficiency. Crucially, the converter maintains performance for oblique incidence up to 45°, while its thickness remains below 0.02λ₀. Another line of work in the X-band has produced ultrathin single-layer anisotropic structures capable of high-efficiency cross-polarisation conversion over a 31.6 % fractional bandwidth (8–11 GHz) and dual-band linear-to-circular conversion around 7.5–7.7 GHz and 11.5–11.9 GHz. These metasurfaces exhibit stable operation against incidence angles up to 45° in both transverse-electric and transverse-magnetic polarisations, underscoring their robustness and multifunctional capability for compact polarisation-control devices.

Polarization Conversion Techniques in Electromagnetic Metasurfaces publication trend

The graph below shows the total number of articles in polarization conversion techniques in electromagnetic metasurfaces across all publications each year (not limited to Nature Index journals).

Technical terms

Metasurface: A two-dimensional array of engineered subwavelength elements that manipulates electromagnetic waves by locally controlling phase, amplitude and polarisation.

Polarisation conversion ratio (PCR): The ratio of power in the desired polarisation state to the total reflected or transmitted power, expressed as a percentage and indicating device efficiency.

Linear polarisation: A polarisation state in which the electric field oscillates along a fixed direction.

Circular polarisation: A polarisation state in which the electric field rotates uniformly in the plane perpendicular to propagation, described as left-handed or right-handed depending on the rotation sense.

Resonant phase delay: The frequency-dependent phase shift introduced by a resonant element, crucial for achieving specified polarisation transformations.

Radar cross section (RCS) reduction: A measure of how effectively a structure suppresses its reflected signature to electromagnetic interrogation, often achieved by phase-engineered metasurfaces.

References

1. Multi-band ultrathin reflective metasurface for linear and circular polarization conversion in Ku, K, and Ka bands. Communications Engineering (2024).
2. Linear and circular-polarization conversion in X-band using anisotropic metasurface. Scientific Reports (2019).
3. Ultra-wide band and high efficient Polarization converting metasurface employing Bell-shaped unit cell for RCS reduction. Results in Engineering (2024).
4. Ultra-wideband high-efficiency reflective linear-to-circular polarization converter based on metasurface at terahertz frequencies.. Optics Express (2017).
5. Ultra-broadband wide-angle linear polarization converter based on H-shaped metasurface.. Optics Express (2018).