2.7  μm optical vortex beam directly generated from an Er:Y₂O₃ ceramic laser

Area of Science:

• Laser Physics
• Photonics
• Quantum Optics

Background:

• Vortex beams, characterized by orbital angular momentum, have diverse applications in optical manipulation and communication.
• Generating vortex beams in the 3 µm spectral region is challenging due to material limitations and laser design complexities.

Purpose of the Study:

• To demonstrate the first direct generation of vortex beams in the 3 µm spectral region.
• To achieve controllable handedness and high purity in the generated vortex beams.
• To quantitatively evaluate the orbital angular momentum of the produced beams.

Main Methods:

• Utilized an Erbium-doped Yttrium Oxide (Er:Y2O3) ceramic laser.
• Introduced asymmetric cavity loss to control beam handedness.
• Reduced the number of longitudinal modes for high purity.

Main Results:

• Successfully generated direct vortex beams in the 3 µm spectral region.
• Achieved controllable handedness with high purity.
• Quantitatively measured orbital angular momentum of 0.95ħ (LG0,+1 mode) and -0.94ħ (LG0,-1 mode).
• Observed optical spectra centered at 2710.8 nm and 2710.5 nm.

Conclusions:

• The Er:Y2O3 ceramic laser system is effective for direct vortex beam generation in the 3 µm region.
• The method provides a reliable way to produce high-purity vortex beams with controllable handedness.
• This advancement opens possibilities for new applications of vortex beams in the mid-infrared spectrum.