Simplified intracavity phase plates for increasing laser-mode discrimination

Area of Science:

• Optics and Photonics
• Laser Physics
• Diffractive Optics

Background:

• Traditional laser resonators face challenges in simultaneously achieving high modal discrimination and low fundamental-mode loss.
• Diffractive optical elements offer novel approaches to manipulate light within laser cavities.

Purpose of the Study:

• To introduce and analyze a new class of laser resonators employing diffractive mirrors and intracavity diffractive phase elements.
• To investigate methods for achieving simultaneous high modal discrimination and low fundamental-mode loss in these resonators.

Main Methods:

• Utilized sinusoidal and pseudorandom diffractive phase elements.
• Approximated a single-step phase modulation element with a Gaussian function.
• Derived explicit expressions for modal discrimination with a Gaussian output mirror.
• Performed numerical simulations for a phase element with a step singularity, resulting in a super-Gaussian fundamental mode.

Main Results:

• Achieved simultaneous high modal discrimination and low fundamental-mode loss using specific diffractive elements.
• Analyzed the impact of phase element radius, position, and cavity Fresnel number on modal discrimination.
• Identified optimal resonator configurations with plane output mirrors (striped or circular) for enhanced performance.

Conclusions:

• The proposed diffractive laser resonators offer superior modal control compared to conventional designs.
• Optimized diffractive phase elements and output mirror geometries are crucial for maximizing laser performance.
• This work provides a pathway for designing highly efficient and mode-selective laser systems.