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Orbital angular momentum generation in two-mode fiber, based on the modal interference principle.
Optics Letters
|February 16, 2019
Summary
Researchers developed a new method for generating orbital angular momentum (OAM) beams using modal interference in two-mode fibers. This technique achieves high-efficiency conversion of light modes into OAM beams, reaching up to 99% efficiency.
Area of Science:
- Optics and Photonics
- Fiber Optics
- Light-Matter Interactions
Background:
- Orbital angular momentum (OAM) offers unique properties for optical applications.
- Generating OAM beams typically requires complex setups.
- Modal interference in optical fibers presents a potential pathway for OAM generation.
Purpose of the Study:
- To demonstrate a novel and efficient method for generating orbital angular momentum (OAM) beams.
- To utilize modal interference in a two-mode fiber for OAM beam generation.
- To achieve high conversion efficiency for OAM beams.
Main Methods:
- Fabrication of micro-waveguides in a two-mode fiber using femtosecond laser micro-processing.
- Implementation of an in-line modal interferometer based on the fabricated micro-waveguides.
- Theoretical and experimental optimization of waveguide parameters to enhance mode conversion efficiency.
Main Results:
- Successful generation of ±1-order OAM beams through modal interference at specific dips.
- Demonstration of ideal conversion from left- or right-handed circular polarized HE11 modes to OAM beams.
- Achieved a high OAM beam generation efficiency of up to 99%, confirmed by interference spectrum and spiral/fork patterns.
Conclusions:
- The proposed method offers a novel and efficient approach for generating OAM beams.
- Modal interference in two-mode fibers provides a practical platform for OAM beam generation.
- Femtosecond laser-written micro-waveguides enable high-efficiency in-line OAM beam generation.
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