Efficient high-charge Laguerre-Gaussian mode conversion by using a periscopic axicon mirror.

Area of Science:

• Optical physics
• Laser beam shaping
• Quantum optics

Background:

• Laguerre-Gaussian (LG) modes are crucial in various optical applications.
• Converting fundamental Gaussian beams to high-charge LG modes using spiral phase plates (SPPs) suffers from reduced efficiency due to transverse intensity deviations.

Purpose of the Study:

• To propose and verify a novel three-step scheme for dramatically improving the conversion efficiency of Gaussian to high-charge LG modes.
• To overcome the limitations of existing methods in high charge plate applications.

Main Methods:

• A three-step conversion process involving a 1st-order SPP, spatial filtering, a periscopic axicon mirror (PAM), and a second high-order SPP.
• Optimization of the PAM parameter to match beam intensity.
• Numerical simulations using the particle-in-cell (PIC) code EPOCH for verification.

Main Results:

• Achieved a total conversion efficiency as high as 91.85% from a fundamental Gaussian beam to a high-charge LG0l mode.
• Demonstrated significantly higher efficiency compared to methods without the PAM.
• Validated the scheme's effectiveness through numerical simulations.

Conclusions:

• The proposed three-step scheme effectively enhances the conversion efficiency of Gaussian to high-charge LG modes.
• The integration of a PAM is critical for intensity matching and efficiency improvement.
• This method offers a viable solution for efficient generation of high-charge LG beams.