Polarization singularities of focused, radially polarized fields

Area of Science:

• Optics and Photonics
• Electromagnetism
• Mathematical Physics

Background:

• Radially polarized electromagnetic fields exhibit complex polarization states when strongly focused.
• Polarization singularities, such as C-lines, L-lines, and V-points, are critical points in the polarization structure.
• Understanding the dynamics and interactions of these singularities is crucial for applications in optical trapping and microscopy.

Purpose of the Study:

• To investigate the types and relationships of polarization singularities in strongly focused, radially polarized electromagnetic fields.
• To demonstrate the annihilation of different polarization singularities through smooth variations of system parameters.
• To analyze specific examples of singularity evolution and collision, including lemon, monstar, star, C-line, and L-line interactions.

Main Methods:

• Theoretical analysis of the polarization state of focused electromagnetic fields.
• Numerical simulations to visualize and track polarization singularities.
• Examination of parameter space, specifically the aperture angle of the focusing lens.

Main Results:

• Identification of multiple types of polarization singularities.
• Demonstration that polarization singularities can annihilate each other.
• Observation of the evolution of a lemon singularity into a monstar, followed by its annihilation with a star singularity.
• Documentation of a rare collision between a C-line and an L-line, resulting in a V-point.

Conclusions:

• The behavior and interactions of polarization singularities are predictable and can be controlled by system parameters.
• The study provides insights into the topological properties of light fields.
• The findings contribute to the fundamental understanding of light polarization and its manipulation.