Stimulated Brillouin Scattering Enhancement Factor Improvement in a 11.6-GHz-Linewidth 1.5-kW Yb-Doped Fiber Amplifier

Abstract

The stimulated Brillouin scattering (SBS) threshold enhancement factor in a pure white noise linewidth broadening Yb-doped fiber amplifier (YDFA) with a short large mode area fiber is theoretically and experimentally studied. We demonstrate a 1064.08 nm, 11.6 GHz linewidth, 1.5 kW output power YDFA with an SBS threshold enhancement of ∼57 (26 W SBS threshold with single frequency seed). The output beam is near-diffraction limited with a beam quality factor of 𝑀 2 = 1.15 and a slope efficiency of up to 87%. No SBS or stimulated Raman scattering effects are observed in the whole power range. Further power scaling is limited by the available pump power in our system.

818 W Yb-doped amplifier with <7 GHz linewidth based on pseudo-random phase modulation in polarization-maintained all-fiber configuration

“…The SBS-limited power seems to be close. Once the SBS dominates, the output power gets saturated and the intensity of the Rayleigh scattering spectrum becomes larger than the SBS spectrum by more than 10 dB [16,22,26]. Judging from the slope efficiency in figure 4(b) and the SBS spectrum in figure 5, the output power is expected to be increased further.…”

“…The linewidth could be varied by adjusting the V π voltage. Laser linewidth was maintained after each amplifier as in other narrow-linewidth HPFL results [17,22]. In broader bandwidth HPFLs, however, linewidth broadening is reported after each amplifier [16,20].…”

“…In this experiment, PM 818 W output power could be achieved from <7 GHz FWHM laser linewidth (6.6 GHz PRBS). We calculated the theoretical SBS threshold power as figure 8, referring to the modified relation [22,33] which consider both laser linewidth and short fiber length. In the case of 9 m effective LMA fiber length, about 1.2 kW SBS threshold power can be achieved at 5 GHz linewidth, and 2.5 kW at 10 GHz.…”

“…This result can help facilitate the development of <10 GHz, >kW PM HPFLs. Figure 1 summarizes the published results of narrowlinewidth, single-mode, Yb-doped HPFLs based on PM and non-PM optical fibers [7,9,[12][13][14][15][16][17][18][19][20][21][22][23], from which the output power per linewidth ratio in the kW regime can be compared.…”

High-gain and low-distortion Brillouin amplification based on pump multi-frequency intensity modulation

“…As one of the strongest nonlinear light-matter interactions, stimulated Brillouin scattering (SBS) has been widely studied in the amplification of weak signals, pulse compression, distributed strain/temperature sensors, slow/fast-light generators, tunable optical filters, and beam shaping. [1][2][3][4][5][6][7][8] More recently, the SBS in optical fibers is found to be able to realize the high-gain amplification of weak signals embedded in strong background noise. [9] The efficient mechanism for weak signal amplification possesses many advantages, such as room temperature operation, compatibility with off-the-shelf telecom equipment and easy-to-filter out most of the background optical noise due to the narrow Brillouin resonance width (∼ 30 MHz in standard single mode optical fibers).…”