Significant SBS suppression in optical fibers via spectral and temporal distribution: A pathway to scalable power transmission

Stimulated Brillouin scattering (SBS) typically limits power transmission in optical fibers and the power scalability of fiber lasers and amplifiers, particularly in applications requiring narrow-linewidth operation. In this study, we experimentally characterize SBS suppression through time modulation and multiwavelength operation when transmitting laser beams in 1.5-µm range through optical fibers. A continuous-wave (CW) narrow line-width input seeder for a Master Oscillator Power Amplifier (MOPA) system is replaced by several seeders with different wavelengths. These seeders are then modulated synchronously at high-repetition rates (∼10 MHz; ∼50 ns pulses), in a complementary manner – when one is active, the other is inactive. This hybrid method effectively mitigates SBS gain while maintaining a pseudo-continuous-wave (pseudo-CW) operation with multiple relatively narrow wavelengths. Experimental results indicate the conditions under which this mitigation occurs. For pulse widths exceeding 10 ns and inter-pulse delays greater than 50 ns we demonstrate an increase of at least two orders of magnitude in the SBS threshold compared to the single CW seed source operation with a band width of 1.7 MHz. To the best of our knowledge, this is the first experimental observation of such a significant SBS suppression under these conditions. Our findings present a viable pathway for SBS-free, high-power transmission in optical fibers, with potential applications in high-power fiber laser systems, fiber remote charging, sources for free space telecommunications, material processing, and defense.