Ring resonator for lasers with annular gain media

Area of Science:

• Optics and Photonics
• Laser Physics
• Optical Engineering

Background:

• Traditional laser resonators face limitations in power extraction efficiency and beam quality.
• Annular gain media offer potential for higher power but require specialized resonator designs.
• Diffraction effects are often detrimental and need careful management in resonator design.

Purpose of the Study:

• To present a novel ring resonator design for lasers utilizing annular gain media.
• To investigate the generation and utilization of azimuthal radiation flux for enhanced power extraction.
• To analyze the impact of diffraction on resonator modes and beam quality.

Main Methods:

• Experimental implementation of a ring resonator with two annular mirrors and a decentered coupling aperture.
• Theoretical modeling of the resonator, including edge diffraction effects at the coupling aperture.
• Characterization of optical power extraction efficiency and beam quality using a diffusion-cooled CO2 laser.

Main Results:

• Demonstration of high optical power extraction from the entire gain volume via azimuthal radiation flux.
• Observation of random jumping between unidirectional and bidirectional operation due to mode degeneracy.
• Achievement of 2x diffraction-limited beams with high extraction efficiencies.
• Experimental stabilization of unidirectional operation, though sensitive to mirror alignment.

Conclusions:

• The proposed ring resonator effectively utilizes azimuthal radiation flux for efficient power extraction from annular gain media.
• Diffraction plays a crucial role in mode formation and operation characteristics, offering opportunities for beam shaping.
• The resonator design shows promise for high-power, high-beam-quality laser systems.