Broadband Multifocal Conic-Shaped Metalens

TL;DR

This paper introduces novel broadband multifocal conic-shaped metalenses that focus light at multiple points with reduced noise and polarization control, enhancing nanoscale imaging performance.

Contribution

It presents two types of conic-shaped metalenses with nanoslits that achieve effective multifocal focusing, broadband operation, and active polarization control, advancing nanophotonic device design.

Findings

Effective multifocal focusing with constructive interference

Broadband operation from 600 nm to 900 nm

Active dual-polarity control via circular polarization

Abstract

Multifocal lens, which focus incident light at multiple foci, are widely used in imaging systems and optical communications. However, for the traditional design strategy, it combines several lenses that have different focal points into a planar integrated unit, resulting a low imaging quality due to the high background noise. Here, we propose two kinds of multifocal metalens with Au nanoslits arranged in an elliptical and a hyperbolic shape, which are able to effectively focus incident light at all of the foci with constructive interference, and extremely decrease the background noise and improve the lens imaging performance at the nanoscale. We further demonstrate that, the proposed metalens can possess a broadband operation wavelength changed from 600 nm to 900 nm, with its dual-polarity actively controlled by the incident circular polarization lights. With great agreement between the experimental and simulation results, our proposed conic-shaped metalens provides a significant potential for the future integrated nanophotonic device.