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Wavelength- and OAM-tunable vortex laser with a reflective volume Bragg grating
Optics Express
|October 19, 2017
Summary
This study presents a tunable vortex laser for optical communications. It uses a novel volume Bragg grating (VBG) to generate orbital angular momentum (OAM) beams, enhancing data capacity.
Area of Science:
- Optics and Photonics
- Optical Communications
- Laser Physics
Background:
- Vortex beams with orbital angular momentum (OAM) are crucial for expanding optical communication capacity.
- OAM mode multiplexing offers a path to higher data rates when combined with existing techniques.
Purpose of the Study:
- To demonstrate a novel wavelength- and OAM-tunable vortex laser operating at 1.6 µm.
- To investigate the use of a volume Bragg grating (VBG) as an OAM-preserving wavelength selector within a laser cavity.
Main Methods:
- A z-shaped laser cavity design was employed, incorporating a reflective VBG as a folding mirror.
- The VBG was theoretically and experimentally validated for its OAM-preserving properties and wavelength selectivity.
Main Results:
- Direct generation of vortex beams with tunable OAM states (0, ±ħ, ±2ħ) was achieved.
- The laser produced beams with a narrow bandwidth (< 0.04 nm) and tunable wavelengths.
- The VBG effectively acted as an OAM-preserving wavelength selector within the laser cavity.
Conclusions:
- A novel, compact, and robust resonant cavity laser for generating tunable vortex beams was successfully developed.
- This technology offers a new approach for optical communications by integrating spatial multiplexing (OAM) with wavelength multiplexing.