Nonlinear imaging with all-dielectric metasurfaces

TL;DR

This paper explores nonlinear dielectric metasurfaces, demonstrating their unique imaging capabilities, including third-harmonic generation and higher-order correlations, challenging classical lens theory and opening new avenues for photonic applications.

Contribution

It introduces a generalized Gaussian lens equation for nonlinear imaging and experimentally demonstrates higher-order spatial correlations in nonlinear metalenses.

Findings

Verified a generalized Gaussian lens equation for nonlinear imaging

Demonstrated third-harmonic imaging of objects

Observed higher-order spatial correlations in nonlinear metalenses

Abstract

Nonlinear metasurfaces incorporate many of the functionalities of their linear counterparts such as wavefront shaping but simultaneously they perform nonlinear optical transformations. This dual functionality leads to a rather unintuitive physical behavior which is still widely unexplored for many photonic applications. The nonlinear processes render some basic principles governing the functionality of linear metasurfaces not directly applicable, such as the superposition principle and the geometric optics approximation. On the other hand, nonlinear metasurfaces facilitate new phenomena that are not possible in the linear regime. Here, we study the imaging of objects through a dielectric nonlinear metalens. We illuminate objects by infrared light and record their generated images at the visible third-harmonic wavelengths. We revisit the classical lens theory and suggest a generalized Gaussian lens equation for nonlinear imaging, verified both experimentally and analytically. We also demonstrate experimentally higher-order spatial correlations facilitated by the nonlinear metalens, resulting in additional image features.