High-power thin-disk lasers emitting beams with axially-symmetric polarizations

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• High-power lasers are crucial for various scientific and industrial applications.
• Controlling laser beam polarization, particularly radial and azimuthal, is essential for advanced applications.
• Existing methods for generating polarized beams often face limitations in power and efficiency.

Purpose of the Study:

• To demonstrate efficient intracavity generation of radially polarized beams from a continuous wave thin-disk laser.
• To develop and analyze nanograting-based polarization converters for femtosecond laser pulses.
• To achieve high-power generation of azimuthally polarized beams with high conversion efficiency.

Main Methods:

• Intracavity generation using circular grating waveguide output couplers (GWOC) for radial polarization selection.
• Detailed analysis of GWOC fabrication tolerances, including duty cycle and grating profile effects.
• Conversion of femtosecond laser pulses from linear to azimuthal polarization using a nanograting-based polarization converter.

Main Results:

• Achieved 750 W average output power with 43% optical efficiency for radially polarized beams.
• Demonstrated conversion of femtosecond laser pulses to azimuthal polarization with >90% efficiency.
• Generated azimuthally polarized beams with up to 850 W average power, 400 fs pulse duration, and 1 MHz pulse repetition rate.

Conclusions:

• Circular grating waveguide output couplers are effective for selecting radial polarization in high-power thin-disk lasers.
• Nanograting-based converters offer a highly efficient method for generating high-power azimuthally polarized femtosecond laser pulses.
• The presented techniques significantly advance the capabilities for generating and controlling high-power polarized laser beams.