Gouy phase induced polarization transition of focused vector vortex beams

Area of Science:

• Optics and Photonics
• Laser Physics
• Material Science

Background:

• Vector vortex beams (VVBs) exhibit complex polarization properties.
• The Gouy phase significantly influences beam propagation and focal characteristics.
• Understanding polarization transitions is crucial for applications like laser material processing.

Purpose of the Study:

• To establish a unified criterion for Gouy phase effects on VVB polarization transitions.
• To investigate the relationship between beam parameters and observed polarization changes.
• To explore the potential of controlled polarization transitions in modifying femtosecond laser-induced surface structures.

Main Methods:

• Theoretical analysis of focused VVBs considering Gouy phase.
• Numerical simulations to visualize polarization evolution and intensity distributions.
• Examination of the dependence on polarization order and topological charge parity.
• Analysis of conditions for cross-polarization transitions based on Gouy phase difference (GPD).

Main Results:

• A common criterion for Gouy phase-induced polarization transition in VVBs was proposed.
• Cross-polarization transitions occur when spin components overlap at specific GPDs ((2k+1)π).
• Focal fields exhibit radially variant polarization due to unequal spin component intensities.
• The parity of the smaller modulus between polarization order and topological charge dictates transition behavior.

Conclusions:

• The study provides a fundamental understanding of polarization transitions in focused VVBs.
• The findings offer a method to control focal field polarization by tuning beam parameters and GPD.
• This controllable polarization transition has potential applications in creating tailored periodic surface structures.