3.05 kW, 13.7 GHz linewidth fiber amplifier based on PRBS phase modulation for SBS suppression.

Area of Science:

• Photonics and Optical Engineering
• High-Power Fiber Lasers

Background:

• Stimulated Brillouin scattering (SBS) is a major limitation in high-power fiber amplifiers.
• Effective suppression of SBS is crucial for achieving high output power and beam quality.

Purpose of the Study:

• To investigate the effectiveness of pseudo-random binary sequence (PRBS) phase modulation for SBS suppression in a multi-stage fiber amplifier.
• To optimize PRBS parameters and experimentally demonstrate high-power amplification.

Main Methods:

• Experimental measurement of stimulated Brillouin gain spectra for modulated and unmodulated configurations.
• Theoretical and experimental investigation of the SBS threshold.
• Optimization of PRBS phase modulation parameters via simulation.
• Implementation of a two-stage preamplifier and counter-pumping main amplifier.

Main Results:

• A maximum output power of 3.05 kW was achieved with a slope efficiency of 85.9%.
• The amplifier operated at a central wavelength of 1050 nm with a linewidth of 13.7 GHz.
• SBS reflectivity was suppressed to below 0.01% at 3.05 kW output power.

Conclusions:

• Pseudo-random binary sequence phase modulation is an effective technique for suppressing SBS in high-power fiber amplifiers.
• The developed multi-stage fiber amplifier demonstrates efficient high-power operation with suppressed SBS.
• The findings pave the way for developing more robust and powerful fiber laser systems.