But due to the extremely reduced feature size of the nanostructures which need to be replicated by the thousands or by the millions even for micro-scale metalenses, they have been often impossible to design at a larger scale in an efficient manner.
But researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated an all-glass, centimetre-scale metalens operating in the visible spectrum, which they could manufacture using conventional chip fabrication methods. Their new approach opens up the application of metalenses to low-light conditions and VR applications where the lens needs to be larger than a pupil, designed at a centimetre-scale.
The results published in Nano Letters under the title “All-Glass, Large Metalens at Visible Wavelength Using Deep-Ultraviolet Projection Lithography” report the mass-fabrication of a 45 metalenses each 1cm in diameter on a 4 inch fused-silica wafer.
"Previously, we were not able to achieve mass-production of centimetre-scale metalenses at visible wavelengths because we were either using electron-beam lithography, which is too time consuming, or a technique called i-line stepper lithography, which does not have enough resolution to pattern the required subwavelength-sized structures," explained Joon-Suh Park, a Ph.D. candidate at SEAS and first author of the paper.