Double helical laser beams based on interfering first-order Bessel beams.

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Nondiffracting beams, such as Bessel beams, are crucial for applications requiring stable beam propagation.
• Helical beams possess orbital angular momentum, enabling advanced optical manipulation and communication.

Purpose of the Study:

• To demonstrate the generation of a nondiffracting double helical beam.
• To validate a theoretical model for the propagation of such beams.
• To show the applicability of the system for both continuous wave and pulsed lasers.

Main Methods:

• Utilized axicons and ±1 vortex phase plates in a common-path interferometric setup.
• Employed linear diffraction theory to derive an analytical expression for beam propagation.
• Conducted experiments with continuous laser light and ultrafast laser pulses.

Main Results:

• Successfully generated a nondiffracting double helical beam.
• Analytical expression for beam propagation showed excellent agreement with experimental results.
• Simulations based on Fresnel diffraction corroborated the theoretical model and experimental findings.

Conclusions:

• The common-path interferometric system effectively generates nondiffracting double helical beams.
• Linear diffraction theory provides an accurate and simple model for beam propagation.
• The demonstrated method is versatile, applicable to both continuous and ultrafast laser sources.