Metalenses are tiny, thin, flat surfaces that are engineered by nanostructures to focus light. The surface has high aspect ratio nanostructures, made in high refractive index materials. This gives metalenses the benefit of being very thin compared to classical refractive optics. Metalenses can replace curved lenses and lens systems that are currently used in optical devices and therefore they allow further miniaturization in sensors and different imaging devices.
Dark field optical microscopy demonstrating lensing effect for a large range of wavelengths.
Top emerging technology
Metalenses is a new and very interesting field of optics. In 2019, World Economic Forum named metalenses as one of top 10 emerging technologies. Currently, it is possible to design metalenses for single wavelengths with high efficiency. Yet, for broadband applications it is not as simple, since the metalens needs to correct for chromatic aberrations.
Like DOEs, it is possible to make metalens designs that correct for chromatic aberrations and even higher order aberrations and one of the interesting features of metalenses is that it is possible to control polarization.
Image of a Fresnel meta lens, demonstrating pillars down to sub 100 nm diameters with perfect vertical sidewalls