Three-dimensional measurements of a millimeter wave orbital angular momentum vortex

Area of Science:

• Electromagnetism
• Optics
• Wave Physics

Background:

• Orbital angular momentum (OAM) vortex beams carry unique phase properties.
• Characterizing OAM vortex beams in three dimensions is crucial for advanced applications.

Purpose of the Study:

• To present initial three-dimensional phase and intensity measurements of a 100 GHz, l=±1 OAM vortex.
• To investigate the spatial characteristics and potential complexities of generated OAM vortex beams.

Main Methods:

• Generated a 100 GHz OAM vortex by illuminating a polypropylene spiral phase plate.
• Utilized a three-dimensional field scanner operating in the W-band (75-100 GHz) for measurements.

Main Results:

• Obtained initial three-dimensional phase and intensity data for the OAM vortex.
• Observed splitting of the OAM phase dislocation at the vortex center.
• Identified a complex inner vortex intensity pattern resulting from the dislocation splitting.

Conclusions:

• The study provides foundational 3D characterization of a specific OAM vortex.
• The observed phase dislocation splitting indicates complex beam behavior requiring further investigation.
• These findings contribute to understanding and manipulating OAM vortex beams.