# Multifunctional Meta-Devices for Full-Polarization Rotation and Focusing in the Near-Infrared

## TL;DR

This paper introduces a new type of optical device that can control and focus light with various polarization states, enabling advanced micro-nanoscale optical manipulation.

## Contribution

A novel multi-channel and spatial-multiplexing interference strategy for full-polarization control using birefringent metasurfaces.

## Key findings

- Highly efficient multi-channel polarization rotation meta-devices were demonstrated.
- The devices achieved ultra-high polarization extinction ratios and high focusing efficiencies.
- The approach enables independent control of wavefronts at different circular polarizations.

## Abstract

The creation of multi-channel focused beams with arbitrary polarization states and their corresponding optical torques finds effective applications in the field of optical manipulation at the micro-nanoscale. The existing metasurface-based technologies for polarization rotation have made some progress, but they have been limited to single functions and have not yet achieved the generation of full polarization. In this work, we propose a multi-channel and spatial-multiplexing interference strategy for the generation of multi-channel focusing beams with arbitrary polarization rotation based on all-dielectric birefringent metasurfaces via simultaneously regulating the propagation phase and the geometric phase and independently controlling the wavefronts at different circular polarizations. For the proof of concept, we demonstrate highly efficient multi-channel polarization rotation meta-devices. The meta-devices demonstrate ultra-high polarization extinction ratios and high focusing efficiencies at each polarization channel. Our work provides a compact and versatile wavefront-shaping methodology for full-polarization control, paving a new path for planar multifunctional meta-optical devices in optical manipulation at micro–nano dimensions.