An inverse designed achromatic flat lens operating in the ultraviolet

TL;DR

This paper presents a numerically simulated inverse-designed achromatic flat lens for ultraviolet light, achieving high efficiency and wide field of view, advancing UV optical system miniaturization.

Contribution

It introduces a novel inverse design method for a broadband, achromatic UV flat lens with record off-axis efficiency and polarization insensitivity.

Findings

Average on-axis efficiency ~86%

Off-axis efficiency ~67% at 30° field of view

First reported high-efficiency UV achromatic metalens

Abstract

We demonstrate an inverse designed achromatic, flat, polarization-insensitive diffractive optic element, i.e., multilevel diffractive lens (MDL), operating across a broadband range of UV light (250 nm - 400 nm) via numerical simulations. The simulated average on-axis focusing efficiency of the MDL is optimized to be as high as ~86%. We also investigate the off-axis focusing characteristics at different incident angles of the incoming UV radiation such that the MDL has a full field of view of 30 degrees. The simulated average off-axis focusing efficiency is ~67%, which is the highest reported till date for any chromatic or achromatic UV metalens or diffractive lens to the best of our knowledge. The designed MDL is composed of silicon nitride. The work reported herein will be useful for the miniaturization and integration of lightweight and compact UV optical systems.