Cavity-induced SAM to OAM conversion for sub-wavelength focused chiral field generation

Area of Science:

• Optics and Photonics
• Nanotechnology
• Physical Chemistry

Background:

• Chiral fields are crucial for manipulating chiral matter at the nanoscale.
• Generating and controlling these fields with high precision remains a challenge.

Purpose of the Study:

• To demonstrate spin-to-orbital angular momentum (SAM to OAM) conversion for generating focused chiral fields.
• To showcase the utility of these fields for tweezing and separating chiral objects like molecules.

Main Methods:

• Utilized a micron-size Helmholtz hemisphere resonator fed by a circularly polarized Gaussian laser.
• Investigated the interplay between resonator cavity modes and diffraction for sub-wavelength chiral field formation.
• Employed analytical and fully numerical simulations for in-situ motion illustration.

Main Results:

• Generated focused chiral fields with nanoscale chirality density via SAM to OAM conversion.
• Demonstrated the ability of these fields to tweeze and separate radially chiral molecules on surfaces.
• Achieved tunable field generation by adjusting resonator radius and input laser parameters, without plasmonic losses.

Conclusions:

• Developed an effective, tunable tool for nanoscale chiral tweezing and enantiomer separation.
• The proposed method offers a realistic setting with moderate laser intensity.
• Highlights the potential for advanced chiral manipulation in various scientific and technological applications.