Increased frequency conversion of Nd:YAG laser radiation with a variable-reflectivity mirror

Area of Science:

• Optics and Photonics
• Laser Physics
• Nonlinear Optics

Background:

• Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) lasers are widely used for various applications.
• Improving the frequency-doubling efficiency of Nd:YAG lasers is crucial for generating green light.
• Unstable resonators with variable reflectivity mirrors offer potential for enhanced laser performance.

Purpose of the Study:

• To investigate the use of a variable-reflectivity-mirror unstable resonator to enhance the frequency-doubling efficiency of a Nd:YAG laser.
• To quantify the output energy and efficiency of green light generation.
• To analyze the beam divergence of the frequency-doubled output.

Main Methods:

• Utilized a Nd:YAG laser system.
• Incorporated a variable-reflectivity-mirror unstable resonator design.
• Performed frequency doubling experiments at different pulse repetition frequencies (Hz).
• Measured output energy, conversion efficiency, and beam divergence.

Main Results:

• Achieved a significant increase in frequency-doubling efficiency.
• Obtained up to 385 mJ of green light at a pulse repetition frequency of 5 Hz.
• Reached a maximum conversion efficiency of 61%.
• Observed an increase in beam divergence from 0.26 mrad at 0.5 Hz to 0.69 mrad at 5 Hz.

Conclusions:

• The variable-reflectivity-mirror unstable resonator effectively enhances the frequency-doubling efficiency of Nd:YAG lasers.
• High green light output and efficiency are achievable at elevated pulse repetition frequencies.
• Beam divergence is a parameter to consider at higher operating frequencies.