Cubic-Phase Metasurface for Three-Dimensional Optical Manipulation.

Hsin Yu Kuo,Mu Ku Chen,Hiroaki Misawa,Sunil Vyas,Yuan Luo,Din Ping Tsai,Yu-Jung Lu,Xu Shi,Cheng Hung Chu

doi:10.3390/nano11071730

Abstract

The optical tweezer is one of the important techniques for contactless manipulation in biological research to control the motion of tiny objects. For three-dimensional (3D) optical manipulation, shaped light beams have been widely used. Typically, spatial light modulators are used for shaping light fields. However, they suffer from bulky size, narrow operational bandwidth, and limitations of incident polarization states. Here, a cubic-phase dielectric metasurface, composed of GaN circular nanopillars, is designed and fabricated to generate a polarization-independent vertically accelerated two-dimensional (2D) Airy beam in the visible region. The distinctive propagation characteristics of a vertically accelerated 2D Airy beam, including non-diffraction, self-acceleration, and self-healing, are experimentally demonstrated. An optical manipulation system equipped with a cubic-phase metasurface is designed to perform 3D manipulation of microscale particles. Due to the high-intensity gradients and the reciprocal propagation trajectory of Airy beams, particles can be laterally shifted and guided along the axial direction. In addition, the performance of optical trapping is quantitatively evaluated by experimentally measured trapping stiffness. Our metasurface has great potential to shape light for compact systems in the field of physics and biological applications.

Highlights

Optical tweezer [1,2,3] has become an indispensable tool to operate the motion of microor nanoscale objects for biomedical research [4,5,6,7]
The intensity distribution (|Ey|2 ) in the diffracted field from GaN dielectric metasurface with cubic phase at 532 nm is demonstrated by the finite-difference time-domain (FDTD) method
More detailed information about simulated parameters and boundary conditions can be found in the Supplementary Materials in Sections S1 and S2

Summary

Introduction

Optical tweezer [1,2,3] has become an indispensable tool to operate the motion of microor nanoscale objects for biomedical research [4,5,6,7]. Because of a non-contact approach, the manipulation technique can hold, drag and even twist objects without mechanical damage and has been widely used in diverse applications ranging from the biomedical analysis [4,8,9] to micro-robot engineering [10]. Compared with Gaussian beams, non-diffraction and self-healing beams, such as the Bessel beam, Airy beam, Nanomaterials 2021, 11, 1730. The Airy beam has spatially asymmetric intensity distribution, parabolic propagation trajectory, and self-acceleration behavior, which was theoretically found [25] by Berry and Balazs in 1979 and experimentally observed [26] by Siviloglou et al

Methods

Results

Discussion

Conclusion