Metalenses
The concept of metalenses
Metalenses offer a fundamentally different approach to optics compared to conventional refractive lenses by shaping light through nanoscale structures rather than bulk curvature. This allows metalenses to achieve extreme miniaturization, replacing multi-element refractive lens stacks with single, ultra-thin optical layers. They can precisely control phase, amplitude, and polarization at subwavelength scales, enabling advanced functionalities such as aberration correction, flat focusing, and compact wide-angle imaging that are difficult or impossible with traditional optics. In addition, metalenses open the door to multifunctional and co-designed optics-combining focusing, filtering, and beam shaping in one element-while offering the potential for wafer-level fabrication and integration with semiconductor-style manufacturing, something that conventional refractive optics struggle to achieve at scale.
Meta-atoms height
1200 nm
Meta-atoms RI : 2.3
Encapsulant RI : 1.5
Meta-atoms height
600 nm
Meta-atoms RI : 2.55
Encapsulant RI : 1.12
Meta-atoms HiRI-COAT: RI = 2.55
Encapsulant AIR-COAT: RI = 1.12
MULTILAYER: Stacked HiRI-COAT metasurfaces and AIR-COAT encapsulant
From a physical standpoint, metalenses operate by engineering spatially varying phase delays across the surface to reproduce the wavefront of a conventional lens. This phase control is achieved through mechanisms such as resonant scattering, propagation phase accumulation within high-index nanostructures, or geometric (Pancharatnam-Berry) phase for polarization-dependent designs. By tailoring these effects at a subwavelength pitch, metalenses can implement arbitrary phase profiles.
Why is it different?
FABRICATION
CONTRAST
STACK
As the optical function is encoded at the nanoscale, metalense can correct aberrations (e.g. spherical aberration, coma) directly at the surface and enable compact focusing with high numerical aperture. However, chromatic dispersion remains a central challenge, as the phase response of the nanostructures is inherently wavelength-dependent. Advanced designs mitigate this through dispersion-engineered meta-atoms or multi-layer metasurfaces.
Overall, metalenses provide precise wavefront shaping in an ultra-thin form factor, bridging nanofabrication, electromagnetics, and optical design, and enabling optical functionalities that are difficult to realize with conventional refractive elements.
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