Mechanical Characterization of Broadband Achromatic Optical Vortex Metalens

Abstract

Metalenses, which may effectively manipulate the wavefront of incident light, have been proposed and extensively utilized in the development of various planar optical devices for specialized purposes. However, similar to traditional lenses, the metalens suffers from chromatic aberration problems due to the significant phase dispersion in each unit structure and the limited operational bandwidth. To mitigate the impact of chromatic aberration, we integrate a phase compensation approach with a novel utilization of a phase shift function to define the adjusted phase criterion satisfied by each α-Si resonance unit. This approach may lead to development of an innovative optical tweezer known as an achromatic optical vortex metalens (AOVM), offering reliable focusing capabilities across the 1300 nm and 1600 nm incident light range. Numerical simulations are conducted to investigate the optical properties of 200 nm diameter SiO2 particles at the focal plane of the AOVM. The trapping ability of the AOVM is successfully validated, exhibiting favorable characteristics including constant optical force, stable kinematic state of trapped particles, and consistent capture positions, surpassing those of the optical vortex metalens.