Work

Four-channel polarization-multiplexed metalens for 3D optical trapping

Year: 2026

Type: article

Abstract: Polarization multiplexing offers an additional degree of freedom for parallel optical manipulation in compact systems. However, simultaneously generating spatially separated foci with prescribed local polarization states under a fixed incident polarization and establishing their three-dimensional trapping stability through optical-force analysis remains challenging. Here, we propose and numerically demonstrate a four-channel polarization-multiplexed Pancharatnam-Berry metalens operating in water at 532 nm. Under x -polarized illumination, the metalens simultaneously forms four off-axis foci in a common focal plane, with prescribed local polarization states corresponding to linear polarization at 30° and 120°, right-circular polarization, and left-circular polarization. The simulated mean FWHMs of the four channels yield ratios of 1.032–1.062 relative to the common scalar Airy FWHM benchmark. Within circular regions of radius 3×FWHM, the target-polarization-projected power accounts for 78.15% of the total encircled power, with an inter-channel power uniformity of 0.931. Maxwell stress tensor calculations for a 0.2-µm-radius SiO 2 sphere at an incident power of 100 mW reveal stable transverse and axial zero-force equilibria and trap depths exceeding 10 k B T in all four channels. These results establish a direct connection between polarization-multiplexed focal-field engineering and channel-dependent optical-force responses, demonstrating a compact approach to parallel three-dimensional optical trapping with polarization-labeled channels.

Source: Optics Express

DOI: 10.1364/oe.612843