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Coherence singularity and evolution of partially coherent Bessel-Gaussian vortex beams
Optics Express
|May 9, 2023
Summary
The topological charge of partially coherent Bessel-Gaussian vortex beams can be determined by counting coherence singularities. This relationship, dependent on an off-axis reference point, is crucial for optical communications.
Area of Science:
- Optical physics
- Beam propagation
- Coherence theory
Background:
- Partially coherent Bessel-Gaussian (PCBG) vortex beams carry topological charge (TC) information within their cross-spectral density (CSD) phase.
- Understanding the relationship between TC and beam properties is vital for advanced optical applications.
Purpose of the Study:
- To investigate and confirm the quantitative relationship between the topological charge (TC) and the number of coherence singularities in PCBG vortex beams.
- To establish a method for measuring the CSD phase of PCBG vortex beams.
- To explore the influence of propagation distance and coherence width on this relationship.
Main Methods:
- Theoretical analysis of PCBG vortex beam propagation.
- Experimental verification using a developed CSD phase measurement scheme.
- Analysis of beam characteristics at varying propagation distances and coherence widths.
Main Results:
- The number of coherence singularities equals the magnitude of the TC for PCBG vortex beams with an off-axis reference point.
- The phase winding direction directly corresponds to the sign of the TC.
- The quantitative relationship was confirmed experimentally across different propagation conditions.
Conclusions:
- A reliable method for determining the TC of PCBG vortex beams has been established.
- The findings provide a foundation for utilizing PCBG vortex beams in optical communication systems.
- This research clarifies a key characteristic of PCBG vortex beams, differentiating them from other vortex beam types.
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