Master oscillator with power amplifiers: performance of a two-element cw HF phased laser array

Area of Science:

• Laser Physics
• Optical Engineering
• Chemical Lasers

Background:

• Phased arrays require high mutual coherence for effective beam combination.
• Master Oscillator Power Amplifier (MOPA) configurations are crucial for high-power laser systems.
• Multiline chemical lasers present unique challenges for coherence control.

Purpose of the Study:

• To experimentally evaluate the performance of a two-element phased array of multiline continuous-wave (cw) HF chemical lasers.
• To measure the mutual coherence of amplified beams in a MOPA configuration.
• To investigate the impact of spectral mismatch and master oscillator spatial coherence on phased array performance.

Main Methods:

• Utilized a two-element phased array of multiline cw HF chemical lasers in a MOPA configuration.
• Measured mutual coherence via interference fringe visibility in the near field.
• Employed white light interferometry to equalize optical path lengths.
• Analyzed spectral data, amplification factors, and mutual coherence measurements.

Main Results:

• Achieved high multiline visibilities of 0.90 +/- 0.02 when optical path difference was minimized.
• Demonstrated that spectral mismatch did not affect amplification factor or mutual coherence.
• Presented experimental data on spectra, amplification, and coherence.

Conclusions:

• The MOPA configuration effectively produced highly coherent beams from the HF chemical laser phased array.
• Optical path length equalization is critical for achieving high fringe visibility.
• Near-field measurements provide valuable insights, but far-field optimization is necessary for precise path length adjustments.