10 W, 2 mJ-level ns all-fiber amplifier at 2.8 µm.

Area of Science:

• Laser Physics and Photonics
• Fiber Optics
• Nonlinear Optics

Background:

• High-power fiber amplifiers are crucial for various scientific and industrial applications.
• Scaling output energy and power in fiber laser systems presents significant challenges.
• Erbium-doped fluoride fibers offer unique properties for mid-infrared amplification.

Purpose of the Study:

• To demonstrate a single-stage, high-energy fiber amplifier in the mid-infrared region.
• To investigate the performance of a master-oscillator power-amplifier (MOPA) configuration using large-core fibers.
• To achieve record pulse energy and output power for nanosecond fiber amplifiers.

Main Methods:

• Fabrication of a single-stage amplifier using two spliced large core erbium-doped fluoride fibers (85 µm and 130 µm diameters).
• Utilized an optical parametric generator (OPG) with ~2 ns pulse duration and 2.8 µm wavelength as the seed source.
• Characterized the amplifier's output power, pulse energy, peak power, and slope efficiency using 940 nm pump light.

Main Results:

• Achieved an average output power of 10 W.
• Recorded a record pulse energy of 2 mJ, corresponding to 1 MW peak power.
• Demonstrated a maximum slope efficiency of 21% with respect to the incident pump power.

Conclusions:

• The demonstrated single-stage fiber amplifier configuration successfully achieved high output power and pulse energy.
• The MOPA architecture using large-core fluoride fibers is a promising approach for further power and energy scaling.
• This work advances the development of high-performance mid-infrared nanosecond fiber laser sources.