Chiral Metamaterials and Optical Activity

Chiral metamaterials are artificially structured composites that lack mirror symmetry and thus interact differently with left- and right-handed circular polarisation of light, yielding optical activity and circular dichroism far beyond what is found in natural materials. By arranging subwavelength elements—such as helices, gammadion motifs or tailored dielectric nanopillars—into bulk volumes or planar metasurfaces, researchers can dictate polarisation rotation and selective absorption across microwave, terahertz and optical frequencies. These bespoke interactions, rooted in resonant electric and magnetic modes, pave the way for compact circular polarisers, chiral sensors, spin-locked photonic circuits and novel platforms for enantiomeric discrimination, highlighting the broad scientific and technological impact of chiral metamaterials.

Research from Nature Portfolio

Recent studies have demonstrated all-dielectric L-shaped silicon nanopillar arrays fabricated via glancing-angle deposition that achieve broadband and enhanced chiroptical response in transmission, with tunable amplitude and operating frequency through simple geometric adjustments, opening avenues for integrated chiral sensors and spin-locked nanowaveguides. Complementing this, high-resolution nanoscale investigations have visualised handedness-dependent Ohmic dissipation as the microscopic origin of circular dichroism in two-dimensional metasurfaces, elucidating the role of non-radiative losses in chiral light–matter interactions. Additionally, planar silicon-based chiral metasurfaces functioning as circular dichroism waveplates have been shown to combine near-unity dichroism and extreme extinction ratios in transmission and reflection, demonstrating a compact route to efficient circular polarisation control.

Chiral Metamaterials and Optical Activity publication trend

The graph below shows the total number of articles in chiral metamaterials and optical activity across all publications each year (not limited to Nature Index journals).

Technical terms

Chirality: Property of a structure or medium that lacks mirror symmetry, leading to different interactions with left- and right-handed circularly polarised light.

Metamaterial: Artificially engineered assembly of subwavelength building blocks designed to produce electromagnetic responses not found in natural materials.

Metasurface: Planar arrangement of nanoscale or microscale structures that manipulates light’s phase, amplitude and polarisation at a two-dimensional interface.

Optical Activity: Phenomenon in which the plane of polarisation of linearly polarised light rotates as it propagates through a chiral medium.

Circular Dichroism: Difference in absorption or transmission between left- and right-handed circular polarisation, arising from chiral asymmetry.

References

1. Self‐Assembly for Creating Vertically‐Aligned Graphene Micro Helices with Monolayer Graphene as Chiral Metamaterials. Advanced Materials (2024).
2. Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials. Nature Communications (2024).
3. Mechanically Tunable Terahertz Circular Polarizer with Versatile Functions. Laser & Photonics Review (2023).
4. Experimental demonstration of the microscopic origin of circular dichroism in two-dimensional metamaterials. Nature Communications (2016).
5. All-dielectric metasurface circular dichroism waveplate. Scientific Reports (2017).