Wavefront shaping enables high-power multimode fiber amplifier with output focus.

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• High-power fiber lasers are crucial for science, industry, and defense.
• Stimulated Brillouin scattering (SBS) limits power scaling in single-frequency fiber laser amplifiers.
• Previous mitigation strategies focused on single-mode or few-mode fibers, limiting power scalability.

Purpose of the Study:

• To explore a highly multimode fiber amplifier for suppressing stimulated Brillouin scattering.
• To investigate the use of spatial wavefront shaping for coherent control of multimode laser amplification.
• To achieve high-power, efficient, and narrow-linewidth output from a fiber laser amplifier.

Main Methods:

• Utilized a highly multimode fiber amplifier design.
• Implemented a spatial wavefront shaping technique on the input light.
• Analyzed SBS suppression through reduced light intensity and spectral broadening in a large fiber core.

Main Results:

• Achieved significant suppression of stimulated Brillouin scattering in the multimode fiber amplifier.
• Demonstrated focusing of the amplified output beam to a diffraction-limited spot using wavefront shaping.
• Obtained high-power, high-efficiency, and narrow-linewidth laser output, ensuring high coherence.

Conclusions:

• Multimode fiber amplifiers, combined with wavefront shaping, effectively suppress SBS for power scaling.
• Optical wavefront shaping provides coherent control over multimode laser amplification.
• Potential applications include coherent beam combining, large-scale interferometry, and directed energy delivery.