Fullwave Maxwell inverse design of axisymmetric, tunable, and multi-scale multi-wavelength metalenses

TL;DR

This paper introduces advanced inverse-design techniques for axisymmetric metalenses that are tunable, multi-wavelength, and scalable, enabling complex optical functionalities validated through experimental fabrication.

Contribution

It presents novel axisymmetric inverse-design methods for reconfigurable and multi-wavelength metalenses, with experimental validation and scalable fullwave Maxwell simulations.

Findings

Reconfigurable lenses can shift focal spots with refractive-index changes

Multi-wavelength lenses operate at 1μm and 10μm wavelengths

Experimental validation achieved for a near-infrared monochrome lens

Abstract

We demonstrate new axisymmetric inverse-design techniques that can solve problems radically different from traditional lenses, including \emph{reconfigurable} lenses (that shift a multi-frequency focal spot in response to refractive-index changes) and {\emph{widely separated}} multi-wavelength lenses ($\lambda = 1\,\mu$m and $10\,\mu$m). We also present experimental validation for an axisymmetric inverse-designed monochrome lens in the near-infrared fabricated via two-photon polymerization. Axisymmetry allows fullwave Maxwell solvers to be scaled up to structures hundreds or even thousands of wavelengths in diameter before requiring domain-decomposition approximations, while multilayer topology optimization with $\sim 10^5$ degrees of freedom can tackle challenging design problems even when restricted to axisymmetric structures.