Polarization-Insensitive Metalenses at Wavelengths in Ultraviolet Region

Metasurfaces in the ultraviolet band have attracted current research concern due to the expanding requirement for wearable UV optical and ultra-compact systems. The constraints of traditional plasmonic metasurfaces operating in transmission mode can be controlled by using an appropriate dielectric material. A metalens presents promising wavefront engineering for multiple applications. Metalenses have sophisticated advanced technology in the progress of miniaturized and integrated optical devices. However, metalenses using the Pancharatnam– Berry (PB) phase or resonance adjusting technique are limited to polarization reliance and for different applications, polarization-insensitive metalenses are extremely preferable. We present three designs of high-efficiency dielectric polarization-insensitive UV metalens using cylindrical nanopillars with focusing efficiency, offering full phase delay in a broadband spectrum of Ultraviolet light (380–400nm). The designed metalenses include titanium dioxide (cylindrical nanopillars on a glass substrate with geometrically different radii and present magnificent polarization-insensitive operation in the broadband UV band. It will considerably advance the miniaturization and integration of the UV photonic devices by limiting the use of Plasmonics structures that are undefended to the ohmic losses and absorption of the metals. The focusing efficiency of the designed metalenses is as high as 43%, 45%, and 47% for the designed wavelengths of metalenses $\lambda_{d}=396\text{n}\text{m}$, 388 nm, and 380 nm, respectively.