102 W monolithic single frequency Tm-doped fiber MOPA

Area of Science:

• Photonics and Optics
• Laser Physics
• Materials Science

Background:

• Thulium-doped fiber amplifiers (TDFAs) are crucial for generating light in the 2-micron wavelength range.
• Achieving high output power while maintaining single-frequency operation in TDFAs presents significant challenges.
• Previous TDFAs have been limited in output power due to parasitic effects and nonlinearities.

Purpose of the Study:

• To demonstrate a high-power, monolithic, all-fiber single-frequency thulium-doped fiber amplifier.
• To investigate the performance limitations, including SBS threshold, of such amplifiers.
• To establish a new power benchmark for monolithic all-fiber lasers near 2 μm.

Main Methods:

• Utilized a monolithic master oscillator power amplifier (MOPA) configuration.
• Employed a thulium-doped fiber as the gain medium.
• Characterized output power, central wavelength, and slope efficiency.
• Analyzed and estimated the stimulated Brillouin scattering (SBS) threshold.

Main Results:

• Achieved a maximum output power of 102 W at a central wavelength of 1.97 μm.
• Observed a slope efficiency of approximately 50% with respect to absorbed pump power.
• Confirmed the absence of parasitic lasing and nonlinear effects.
• Determined that the output power was not limited by the SBS threshold.

Conclusions:

• Successfully demonstrated the first monolithic all-fiber laser with average power exceeding 100 W near 2 μm.
• The MOPA configuration effectively suppresses parasitic lasing and nonlinearities.
• The amplifier's power scalability is promising, with potential for further increases by enhancing pump power.