Trapping and manipulation of nanoparticles using multifocal optical vortex metalens

Abstract

Optical trapping and manipulation have emerged as a powerful tool in the biological and physical sciences. In this work, we present a miniature optical tweezers device based on multifocal optical vortex metalens (MOVM). The MOVM is capable of generating multiple focal fields with specific orbital angular momentum at arbitrary position. The optical force of the vortex field exerted on both high-refractive-index particle and low-refractive-index particle are analyzed. The simulation results show that the two kinds of dielectric particles can be trapped simultaneously. Besides, it is also feasible to manipulate plasmonic nanoparticles even under the resonant condition, which is realized by constructing a 4Pi focusing system with metalenses. Moreover, the metalens can be made into an array format that is suitable for trapping and manipulating various nanoparticles with diverse motion behaviors. The work illustrates the potential of such optical tweezers for further development in lab-on-a-chip devices, and may open up new avenues for optical manipulation and their applications in extensive scientific fields.

All-dielectric silicon metalens for two-dimensional particle manipulation in optical tweezers

“…Furthermore, we expanded the concept to realize a dielectric vortex metalens, which was used to create a donut-shaped intensity distribution in the focal region without the need for an additional phase mask (q-plate). Theoretical concepts for the orbital angular momentum (OAM) transfer with dielectric vortex metalens already exist but have not been experimentally demonstrated yet [24]. In this work, we show that optically trapped particles can indeed rotate in a circular motion based on the topological charge of the helical phase front.…”

“…The abrupt phase change follows for circularly polarized light that is converted to its opposite helicity. This concept enables our device to work either as a convex or concave lens based on the used input circular polarization state [14,23,24]. We demonstrate polarization-sensitive twodimensional (2D) drag and drop manipulation of polystyrene microbeads suspended in water.…”

Controlled Mechanical Motions of Microparticles in Optical Tweezers

“…The angular momentum of light has two forms, spin angular momentum (SAM) and orbital angular momentum (OAM). Both SAM and OAM of light can be conveyed to particles through absorption and scattering, and result in torque that rotates the objects in addition to the usual trapping operation [ 69 , 70 , 71 , 72 ]. As shown in Figure 5 a, the transfer of SAM from circularly polarized light to nearly perfectly spherical vaterite crystals, which has similar birefringence properties to calcite [ 16 ], can cause this crystal to rotate in a speed up to 1000 Hz [ 73 ].…”

Single-shot measurement of phase and topological properties of orbital angular momentum radiation through asymmetric lateral coherence

“…The importance of this peculiar property of light comes from the huge impact that it is having on different fields of research such as telecommunication, quantum information and computing, microscopy, as well as physics and astrophysics. Among the most recent remarkable results, a few are worth mentioning: bandwidth information has been increased by encoding l in the transmitted beam [2], resolution has been pushed beyond the diffraction limit [3], nanoparticles can be finely controlled and manipulated [4], high contrast coronagraphy can be effectively implemented in astrophysics research [5], and novel photoelectric effect rules have been evidenced [6].…”