High-power linearly-polarized single-frequency thulium-doped fiber Master-Oscillator Power-Amplifier

Area of Science:

• Laser Physics
• Fiber Optics
• Photonics

Background:

• High-power fiber lasers are crucial for various applications.
• Thulium (Tm)-doped fiber lasers offer unique emission properties in the 2-micrometer wavelength range.
• Developing narrow-linewidth, high-power sources is an ongoing challenge.

Purpose of the Study:

• To demonstrate a high-power, narrow-linewidth laser source operating around 2 micrometers.
• To investigate the performance of a thulium-doped fiber master-oscillator power amplifier (MOPA) system.
• To identify power limitations and explore scaling prospects.

Main Methods:

• A distributed-feedback master-oscillator (DFB-MO) using Tm-doped fiber was designed.
• The MO was followed by three Tm-doped fiber amplifier stages.
• In-band pumping at 1565 nm and cladding-pumping at 795 nm were utilized for amplification.

Main Results:

• A single-frequency output power of 100 W was achieved at 1943 nm.
• The beam quality was excellent, with a beam propagation factor (M(2)) of 1.25.
• A high polarization extinction ratio of >94% was recorded.

Conclusions:

• The developed Tm-doped fiber MOPA system represents a significant advancement in high-power 2-micrometer sources.
• Thermally-induced damage in the final amplifier stage was identified as the primary power limitation.
• Further power scaling is feasible with improved thermal management and amplifier design.