kW-level monolithic single-mode narrow-linewidth all-solid photonic bandgap fiber amplifier

Area of Science:

• Laser Physics
• Photonics
• Optical Engineering

Background:

• High-power fiber lasers are essential for applications like laser beam combining.
• Transverse Mode Instability (TMI) has limited power scaling in previous fiber laser designs.
• Photonic bandgap fibers offer large mode areas and mode suppression for power scaling.

Purpose of the Study:

• To demonstrate a TMI-limited single-mode output power exceeding previous records.
• To investigate the use of photonic bandgap fibers for high-power laser amplification.
• To achieve the highest output power from a photonic bandgap fiber amplifier to date.

Main Methods:

• Utilized a monolithic fiber amplifier configuration.
• Employed a 25/400 photonic bandgap fiber.
• Broadened the spectral linewidth to approximately 8 GHz to mitigate stimulated Brillouin scattering.

Main Results:

• Achieved a TMI-limited single-mode output power of 1.37 kW.
• Demonstrated the highest output power from a photonic bandgap fiber amplifier reported to date.
• Successfully suppressed stimulated Brillouin scattering through spectral linewidth broadening.

Conclusions:

• Photonic bandgap fibers are a viable technology for scaling fiber laser power.
• The demonstrated power level represents a significant advancement for high-power fiber laser systems.
• Further research can explore even higher power levels and different fiber designs.