Trapping volume control in optical tweezers using cylindrical vector beams

Area of Science:

• Physics
• Optical Engineering
• Nanotechnology

Background:

• Optical trapping utilizes focused laser beams to manipulate microscopic particles.
• Traditional optical traps often use linearly or circularly polarized light, limiting control over trap geometry.
• Cylindrical vector beams (CVBs) offer spatially varying polarization, presenting new possibilities for optical manipulation.

Purpose of the Study:

• To investigate the optical trapping of spherical microparticles using cylindrical vector beams (CVBs).
• To quantify the control over optical trap strength and geometry afforded by CVBs.
• To compare experimental findings with theoretical predictions based on T-matrix scattering theory.

Main Methods:

• Three-dimensional tracking of Brownian motion of trapped microparticles.
• Extraction of optical trap spring constants from positional fluctuations.
• Characterization of trap geometry using the aspect ratio of spring constants.
• Systematic variation of the polarization angle of the CVBs.

Main Results:

• Demonstrated ability to control optical trap strength and geometry by adjusting CVB polarization.
• Quantified the relationship between polarization angle and trap spring constants.
• Experimental results show good agreement with the T-matrix theoretical model.

Conclusions:

• CVBs provide an additional degree of freedom for optical trapping control.
• Polarization adjustment in CVBs enables tunable optical trap characteristics.
• This work advances the understanding and application of advanced light fields in optical manipulation.