Moiré Metasurfaces and Photonic Crystals

Moiré metasurfaces and photonic crystals represent a convergence of periodic nanostructures and controlled light–matter interaction, in which the superposition of two or more patterned layers yields a new emergent lattice. By twisting or mismatching the period of individual layers, moiré patterns introduce long-range modulation that reshapes the photonic band structure, leading to phenomena such as band flattening, slow light and symmetry-protected resonances. These structures enable access to bound states in the continuum, topological phase singularities and tailored orbital angular momentum, opening pathways to on-chip optical vortices, low-threshold lasing, advanced sensing and compact information processors. The interplay between dielectric contrast and moiré geometry allows highly localised modes, high quality factors and reconfigurable response across spectral regimes from the visible to the mid-infrared. As such, moiré metasurfaces and photonic crystals promise a versatile platform for next-generation photonic devices that require precise phase, amplitude and dispersion control.

Research from Nature Portfolio

Recent studies have identified a non-trivial twist-enabled coupling mechanism in bilayer photonic crystals, whereby a bound state in the continuum is accessed through the moiré channel and radiates robust optical vortices carrying orbital angular momentum. This mechanism shows resilience to geometric disturbances, suggesting potential for integrated vortex sources and information processing. Complementary work has realised topological phase singularities in atomically thin semiconductor films combined with optical resonators, producing rapid phase changes and perfect absorption. By harnessing these singularities, researchers have achieved refractive-index sensing with superior phase sensitivity, thereby broadening the toolkit for flat-optics phase engineering.

Moiré Metasurfaces and Photonic Crystals publication trend

The graph below shows the total number of articles in moiré metasurfaces and photonic crystals across all publications each year (not limited to Nature Index journals).

Technical terms

Moiré pattern: A large-scale interference pattern formed by overlaying two periodic lattices with a relative twist or mismatch.

Metasurface: A two-dimensional array of subwavelength scatterers engineered to mould electromagnetic wavefronts and phase fronts.

Photonic crystal: A material with periodically varying refractive index that controls light propagation via photonic bandgaps.

Bound state in the continuum: A non-radiating resonance embedded in the radiation continuum, accessible through symmetry breaking or perturbations.

Flatband: A photonic band exhibiting negligible dispersion across the Brillouin zone, promoting slow-light and localisation phenomena.

References

1. Twisted moiré photonic crystal enabled optical vortex generation through bound states in the continuum. Nature Communications (2023).
2. Modeling the optical properties of twisted bilayer photonic crystals. Light: Science & Applications (2021).
3. Topological phase singularities in atomically thin high-refractive-index materials. Nature Communications (2022).
4. Magic configurations in moiré superlattice of bilayer photonic crystals: Almost-perfect flatbands and unconventional localization. Physical Review Research (2022).
5. On-chip light trapping in bilayer moiré photonic crystal slabs. Applied Physics Letters (2022).