High power single-longitudinal-mode CO₂ laser with a frequency-tunable range of 0.29 GHz

Area of Science:

• Optics and Photonics
• Laser Physics
• Applied Physics

Background:

• Master oscillator power amplifier (MOPA) systems are crucial for tunable laser applications.
• Radio-frequency (RF)-excited waveguide carbon dioxide (CO2) lasers offer advantages in compactness and efficiency.
• Achieving single-longitudinal-mode operation with wide tunability is a key challenge in laser development.

Purpose of the Study:

• To demonstrate a frequency-tunable, single-longitudinal-mode MOPA system.
• To investigate the performance of an RF-excited waveguide CO2 laser for lidar applications.
• To achieve a wide continuous tuning range within a single longitudinal mode.

Main Methods:

• Utilized an RF-excited waveguide CO2 laser as the master oscillator.
• Implemented a three-stage amplification configuration using folded-waveguide CO2 amplifiers.
• Employed a closed-loop cavity length adjustment for frequency tuning.

Main Results:

• Achieved a continuous tuning range of 0.29 GHz within the longitudinal mode spacing.
• Obtained a maximum output power of 23.7 W at 9.56 μm (9P(20) line).
• Demonstrated an amplification factor of 17 with three seven-channel amplifiers.
• Measured a laser linewidth of 3.9 MHz.

Conclusions:

• The developed laser system is highly frequency-tunable and operates in a single longitudinal mode.
• The system exhibits significant output power and amplification, suitable for demanding applications.
• This RF-excited waveguide CO2 laser MOPA system is a promising candidate for coherent detection lidar.