Shaping the Arago-Poisson spot with incomplete spiral phase modulation

Area of Science:

• Optics and Photonics
• Wave Phenomena
• Light-Matter Interactions

Background:

• The Arago-Poisson spot is a key phenomenon demonstrating the wave nature of light.
• Orbital angular momentum (OAM) of light is another fundamental property with significant applications.
• Connecting these phenomena could lead to new optical control methods.

Purpose of the Study:

• To demonstrate a novel method for shaping the Arago-Poisson spot.
• To explore the relationship between the Arago-Poisson spot and OAM.
• To investigate the effect of spiral phase modulation on light diffraction.

Main Methods:

• Utilizing a spatial light modulator to create holographic gratings.
• Generating incomplete spiral phase profiles with five- and tenfold symmetry.
• Modulating phase fronts of incident light beams.
• Analyzing experimental results using Poynting vector flow visualization and OAM spectra decomposition.

Main Results:

• Observed gradual formation of on-axis bright spots upon propagation for incomplete spiral phases.
• Established a connection between the Arago-Poisson spot and OAM by varying phase height.
• Demonstrated controllable mixing of Gaussian and OAM beams.

Conclusions:

• Spiral phase modulation is an effective tool for shaping light diffraction.
• The study provides a visual and spectral understanding of the interplay between Arago-Poisson spots and OAM.
• Potential applications in optical manipulation and beam shaping are highlighted.