Switchable optical trapping based on vortex-pair beams generated by a polarization-multiplexed dielectric...

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Optical trapping is crucial for microparticle manipulation but faces limitations in multiparticle handling and integration.
• Existing methods struggle with flexible control and simultaneous trapping of multiple microparticles.

Purpose of the Study:

• To propose and demonstrate a switchable optical trapping scheme for microparticles.
• To overcome limitations in multiparticle trapping and flexible manipulation using a novel optical setup.

Main Methods:

• Fabrication and characterization of a miniaturized all-dielectric metasurface composed of titanium dioxide nanoposts.
• Generation of polarization-tuned two-fold vortex-pair beams by the metasurface.
• Demonstration of switchable trapping by adjusting polarization (transverse electric and transverse magnetic) and vortex beam properties.

Main Results:

• The metasurface successfully generated tunable vortex-pair beams with controllable topological charges and phase singularity separations.
• Single microparticle trapping was achieved with opposite topological charge vortex pairs under transverse electric polarization.
• Simultaneous trapping of two microparticles was demonstrated with same topological charge vortex pairs under transverse magnetic polarization.

Conclusions:

• The proposed switchable optical trapping scheme offers enhanced integration and flexible manipulation capabilities for multiple particles.
• This technology holds significant potential for applications in biophysics, nanotechnology, and photonics.
• The polarization-tunable metasurface provides a versatile platform for advanced optical manipulation techniques.