Fourier transform-limited, nanosecond, CW-seeded optical parametric amplifier with high spectral purity

Area of Science:

• Laser Physics
• Spectroscopy
• Optical Engineering

Background:

• Continuous wave (CW)-seeded optical parametric amplifiers (OPAs) offer potential for generating narrow linewidth nanosecond pulses.
• High spectral purity and stability are crucial for applications like gas sensing and LIDAR.

Purpose of the Study:

• To develop and characterize a CW-seeded nanosecond pulse OPA system.
• To evaluate its performance for methane absorption spectroscopy.
• To assess its suitability for gas-sensing LIDAR systems.

Main Methods:

• Seeding a nanosecond pulse OPA with a tunable CW laser diode at 1647 nm.
• Pumping the OPA with a 1030 nm fiber laser (10 W average power, 10 ns pulse duration, 100 kHz repetition rate).
• Characterizing spectral purity, linewidth, conversion efficiency, and beam quality; demonstrating methane absorption spectroscopy.

Main Results:

• Achieved a maximum signal conversion efficiency of 21% (2.16 W average power, 20 µJ pulse energy).
• Obtained spectral purity > 99.97% and a spectral linewidth < 110 MHz (near Fourier transform-limited).
• Demonstrated stable methane absorption spectroscopy, confirming source performance.

Conclusions:

• The CW-seeded OPA system provides narrow linewidth, high spectral purity, and excellent stability.
• The demonstrated methane spectroscopy confirms the source's capability for gas sensing.
• This technology shows significant promise for advanced gas-sensing LIDAR systems.