Trapping microparticles in a structured dark focus

TL;DR

This paper demonstrates a novel optical trapping method called Dark Focus Tweezer, which stably traps silica microspheres using a structured dark focus beam, with potential applications in optomechanics and biophysics.

Contribution

It introduces and experimentally validates a new dark focus optical trapping technique with a non-harmonic potential landscape, supported by numerical simulations.

Findings

Stable trapping of silica microspheres achieved.

The trapping potential is non-harmonic and matches simulations.

Potential applications in levitated optomechanics and biophysics.

Abstract

We experimentally demonstrate stable trapping and controlled manipulation of silica microspheres in a structured optical beam consisting of a dark focus surrounded by light in all directions - the so-called Dark Focus Tweezer. Results from power spectrum and potential analysis demonstrate the non-harmonicity of the trapping potential landspace, which is reconstructed from experimental data in agreement to Lorentz-Mie numerical simulations. Applications of the dark tweezer in levitated optomechanics and biophysics are discussed.