Direct experimental evidence for free-space fractional optical vortex transmutation

Area of Science:

• Optics and Photonics
• Quantum Information Science

Background:

• Vortex transmutation offers new methods for optical vortex modulation.
• Fractional optical vortex (FOV) transmutation has been challenging due to generation and detection limitations.

Purpose of the Study:

• To provide experimental evidence for a free-space fractional optical vortex transmutation rule.
• To develop effective methods for generating and detecting fractional optical vortices.

Main Methods:

• Utilized fractional spiral polygonal lenses (FSPLs) for simultaneous wavefront generation and manipulation.
• Employed a deep learning scheme with Bayesian optimization for output vorticity prediction.
• Analyzed far-field diffraction patterns for fractional output vorticity measurement.

Main Results:

• Achieved a data recovery rate of up to 98.2% in vorticity prediction.
• Demonstrated an average error of 0.02 for recognized fractional orbital angular momentum modes.
• Observed FOV central vorticity changing according to a modulo-n transmutation rule in free space.

Conclusions:

• Established a quantitative experimental rule for free-space FOV transmutation.
• FSPLs and deep learning provide a robust framework for FOV generation and detection.
• Results pave the way for applications in quantum information processing and particle manipulation.