Lattice of C points at intensity nulls

Area of Science:

• Optics and Photonics
• Interferometry
• Singularity Physics

Background:

• Fringe contrast in interferometry typically depends on the state of polarization (SOP).
• Interference of more than two beams allows for altered fringe contrast and high contrast fringe generation.
• C points are optical singularities observed in interference patterns.

Purpose of the Study:

• To investigate the generation of dark C points at intensity nulls using a multi-beam interferometer.
• To explore the relationship between the state of polarization and fringe contrast in complex interference patterns.
• To characterize the unusual nature of dark C points arising from overlapping singularities.

Main Methods:

• Utilizing a six-pinhole interferometer setup.
• Employing a specific selection of states of polarization (SOPs) for interfering beams.
• Analyzing intensity distributions and ellipticity to identify V and C points.

Main Results:

• Achieved high contrast fringes through controlled SOPs in a six-beam interference.
• Realized a lattice of dark C points at intensity nulls, distinct from bright C points.
• Demonstrated that dark C points arise from overlapping singularities and destructive interference.
• Observed V points at intensity nulls and C points at extrema in ellipticity distributions.
• Showed that interference of two same-handed bright C points can create an opposite-handed dark C point.

Conclusions:

• Dark C points are unusual optical phenomena occurring at intensity nulls in multi-beam interference.
• The state of polarization plays a critical role in creating and characterizing these singularities.
• This work provides new insights into the nature of optical singularities and their generation through interference.