Fiber-based vortex beam source operating in a broadband or tunable mode

Area of Science:

• Optics and Photonics
• Fiber Optics
• Laser Physics

Background:

• Optical vortex beams possess orbital angular momentum, enabling advanced applications.
• Generating tunable and broadband optical vortices with high purity remains a significant challenge.

Purpose of the Study:

• To demonstrate a novel fiber-based source for generating broadband and tunable optical vortex beams.
• To achieve vector vortices with specific total angular momenta (+2, 0, -2) in the 1100-1400 nm spectral range.

Main Methods:

• Utilized a two-mode birefringent PANDA fiber with stress-applying elements to convert linearly polarized (LP₁₁) modes into vector vortices.
• Generated broadband supercontinuum or tunable Raman solitons in the LP₁₁ modes of a specialized birefringent microstructured fiber using two pulsed lasers.
• Employed a Wollaston prism-based method for pure excitation of LP₁₁ modes.

Main Results:

• Successfully generated vector optical vortices with total angular momenta of +2, 0, and -2.
• Achieved broadband (1100-1400 nm) and tunable operation of the optical vortex beam source.
• Experimentally confirmed high modal and polarization purities of the generated beams.
• Verified the vortex nature of the output beams using shearing interferometry.

Conclusions:

• The demonstrated fiber-based source provides a versatile platform for generating high-purity optical vortex beams.
• The method allows for broadband and tunable operation, expanding possibilities for optical manipulation and communication.