Simple coherent polarization manipulation scheme for generating high power radially polarized beam

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Radially polarized beams offer unique advantages in laser-matter interactions and microscopy.
• Previous methods for generating radially polarized beams often require complex and unstable interferometric setups, such as Mach-Zehnder interferometers.
• Achieving coherent control of polarization states is crucial for efficient beam conversion.

Purpose of the Study:

• To present a novel, simple, and robust scheme for converting a Gaussian beam into an approximated radially polarized beam.
• To overcome the limitations of interferometric stability in previous radially polarized beam generation techniques.
• To demonstrate coherence control suitable for lasers with short temporal coherence lengths.

Main Methods:

• Utilizing coherent polarization manipulation combined with the Poynting walk-off effect in birefringent crystals.
• Employing a symmetrical arrangement of two walk-off crystals and a half-wave plate.
• Implementing a scheme that alleviates the need for high interferometric stability.

Main Results:

• Successfully converted a Gaussian beam into an approximated radially polarized beam.
• Demonstrated coherence control independent of the laser's temporal coherence length.
• Generated 14 watts of radially polarized beam power from an Ytterbium fiber laser.

Conclusions:

• The proposed scheme offers a simpler and more stable alternative for generating radially polarized beams.
• The method is effective even with lasers exhibiting short coherence lengths, broadening its applicability.
• The power output is primarily limited by the input fiber laser power, indicating scalability.