Divide and structure: generating and interswitching orthogonal eigenstates of complementary petal beams using a...

Area of Science:

• Quantum Optics and Structured Light
• Interferometry and Beam Shaping

Background:

• Structured light, including petal beams, is generated by superposing beams with opposite orbital angular momentum (OAM).
• These beams have potential applications in various fields, including optical manipulation and information transmission.

Purpose of the Study:

• To demonstrate a simple and effective scheme for generating complementary petal beams.
• To explore the manipulation of light's helicity and handedness using a modified Sagnac interferometer.

Main Methods:

• Utilized a π-shifted Sagnac interferometer (SI) incorporating a spiral phase plate (SPP) to divide and structure an incoming beam.
• Employed a half-wave plate (HWP) within the SI to switch intensity patterns between interferometer outputs.
• Investigated the effect of the SPP and HWP on counterpropagating beams, analyzing symmetry breaking.

Main Results:

• Successfully generated two azimuthally complementary petal beams, representing orthogonal eigenstates, from a single input beam.
• Demonstrated the ability to interswitch and route these petal beam patterns between the two outputs of the SI using the HWP.
• Showcased that the SI, for general Laguerre-Gaussian (LG) modes, produces two orthogonal output states with complementary petal beams.

Conclusions:

• The proposed π-shifted SI scheme provides a robust method for generating and controlling structured light patterns.
• The observed double symmetry breaking (helicity and handedness) offers insights into light-matter interactions.
• The technique is adaptable for applications in particle trapping, optical communications, and signal processing, particularly multiplexing/demultiplexing with high OAM beams.