Multi-channel electrically tunable varifocal metalens with compact multilayer polarization-dependent metasurfaces and liquid crystals

TL;DR

This paper presents a compact, scalable, electrically tunable varifocal metalens with eight focal lengths, achieved through polarization-dependent metasurfaces and liquid crystals, enabling miniaturized optical systems.

Contribution

It introduces a novel eight-channel electrically tunable metalens combining polarization multiplexing and liquid crystals for scalable focal length control.

Findings

Focal lengths switch among eight values from 3.6 to 9.6 mm.

Total device thickness is approximately 6 mm.

The design is scalable for more focal lengths and miniaturization.

Abstract

As an essential module of optical systems, varifocal lens usually consists of multiple mechanically moving lenses along the optical axis. The recent development of metasurfaces with tunable functionalities holds the promise of miniaturizing varifocal lens. However, existing varifocal metalenses are hard to combine electrical tunability with scalable number and range of focal lengths, thus limiting the practical applications. Our previous work shows that the electrically tunable channels could be increased to 2N by cascading N polarization-dependent metasurfaces with liquid crystals (LCs). Here, we demonstrated a compact eight-channel electrically tunable varifocal metalens with three single-layer polarization-multiplexed bi-focal metalens and three LC cells. The total thickness of the device is ~6 mm, while the focal lengths could be switched among eight values within the range of 3.6 to 9.6 mm. The scheme is scalable in number and range of focal lengths and readily for further miniaturization. We believe that our proposal would open new possibilities of miniaturized imaging systems, AR/VR displays, LiDAR, etc.