Optical and electronic solutions for power stabilization of CO₂ lasers

Area of Science:

• Geophysics
• High-pressure physics
• Laser technology

Background:

• Laser-heated diamond anvil cells (LH-DACs) generate extreme conditions for materials science.
• Precise in situ measurements in LH-DACs demand highly stable laser power sources.
• Typical CO2 gas lasers exhibit significant power fluctuations at second and microsecond timescales.

Purpose of the Study:

• To address the challenge of laser power instability in LH-DAC experiments.
• To develop and demonstrate methods for stabilizing CO2 gas laser power.
• To improve the reliability of in situ measurements under high pressure-temperature conditions.

Main Methods:

• Characterization of power and pointing instabilities in CO2 gas lasers.
• Implementation of direct current modulation for second-timescale power stabilization.
• Utilizing external modulation for microsecond-timescale power stabilization.
• Employing a diffuser or integrating sphere to mitigate pointing instability effects.

Main Results:

• CO2 laser power instabilities measured at ±5% (second timescale) and ~±50% (microsecond timescale).
• Developed methods achieve a stable power output of ±0.3%.
• Demonstrated effective mitigation of pointing instability for accurate power measurements.

Conclusions:

• Stabilized CO2 gas lasers are crucial for reliable LH-DAC research.
• The presented modulation techniques offer practical solutions for laser power stabilization.
• Achieving ±0.3% power stability significantly enhances the accuracy of high pressure-temperature experiments.