Effect of the Number of Longitudinal Modes on Spectral Broadening in a High Power Fiber Amplifier

Peng, Wanjing; Sun, Yunxu; Zha, Congwen; Li, Tenglong; Wu, Juan; Feng, Yujun; Ma, Yanxing; Zhu, Rihong; Tang, Chun

doi:10.1109/lpt.2018.2834357

Cited by 18 publications

(16 citation statements)

References 18 publications

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“…High power linearly polarized all-fiber lasers or MOPAs with narrow linewidth and near diffraction limited beam quality have important applications for nonlinear frequency conversion [1], spectral beam combining (SBC) [2]- [5] and coherent beam combining (CBC) [6]- [8]. However, nonlinear effects (NLE) such as SBS [9], four-wave-mixing (FWM) [10], [11] and mode instability (MI) [12] effects have limited the power scaling of this type of narrow linewidth fiber laser systems. Over the past decade, several methods were employed in these systems for NLE and MI suppression.…”

Section: Introductionmentioning

confidence: 99%

2.5 kW Narrow Linewidth Linearly Polarized All-Fiber MOPA With Cascaded Phase-Modulation to Suppress SBS Induced Self-Pulsing

Feng

Chang

et al. 2020

IEEE Photonics J.

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As a major limitation for power scaling of high power narrow linewidth fiber master oscillator power amplifiers (MOPAs), Stimulated Brillouin Scattering (SBS) induced selfpulsing in polarization maintaining (PM) fiber amplifiers is well characterized and analyzed in this paper by comparing different white noise signal (WNS) phase-modulated modes in experiments. It is found that the self-pulsing effect is not observed in the PM-amplifier with single-frequency laser seed injection, and cascaded WNS modulation provides superior self-pulsing suppression than single WNS modulation with similar output linewidth. Moreover, the experimental results indicate that the self-pulsing threshold can hardly be predicted only by the output linewidth or the defined SBS threshold in a WNS phase modulated fiber amplifier system. As self-pulsing is originated from the spectral spikes in WNS modulated system, we theoretically analyzed characteristics of these spikes in different phase-modulation modes. It indicates the spectral peak intensity can be reduced by cascaded modulation, for which self-pulsing can be suppressed. The theoretical predictions agree well with the experimental results. At the same time, in order to suppress the mode instability effect, a plum blossom shaped bending mode selection device is used in this high-power narrow linewidth fiber amplifier system. Finally, a 32 GHz cascaded WNSs modulated, over than 2.5 kW linearly polarized all-fiber amplifier with a slope efficiency of 86.7% is demonstrated. The polarization extinction ratio (PER) is measured larger than 14 dB and the beam quality factor M 2 maintains lower than 1.3 in the power scaling process.

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Section: Introductionmentioning

confidence: 99%

2.5 kW Narrow Linewidth Linearly Polarized All-Fiber MOPA With Cascaded Phase-Modulation to Suppress SBS Induced Self-Pulsing

Feng

Chang

et al. 2020

IEEE Photonics J.

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“…Therefore, the length of the active fiber in the amplifying section can still be reduced for further SRS suppression. In addition, according to the conclusion in the literature [26], a better SRS suppression can be achieved with shorter fiber in the resonant cavity. The length of the fiber in the current resonant cavity of oscillating section is 8 m, and there is still more room for optimization.…”

Section: Experiments Results Of Bidirectional Pumpingmentioning

confidence: 64%

A 3.5-kW near-single-mode oscillating–amplifying integrated fiber laser

Zeng

Wang

Yang

et al. 2021

High Pow Laser Sci Eng

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The fiber laser based on oscillating-amplifying integrated structure has the potential to take into account the advantages of fiber laser oscillator and amplifier with the characteristics of strong anti-back reflected light ability and high efficiency. Here, we achieved a 3.5 kW near single-mode (M 2~1 .24) oscillating-amplifying integrated fiber laser with an active fiber length of 8 m in the oscillating section and 17.6 m in the amplifying section. While operating at the maximum power, the optical-to-optical conversion efficiency is 87.0%, and the intensity of stimulated Raman scattering is about 23.61 dB lower than the signal light. As far as we know, this is the highest output power of the oscillating-amplifying integrated fiber laser, accompanied with the best beam quality and the highest efficiency.

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“…According to the previous research, the fiber amplifier based on FO seed has obvious spectral broadening due to FWM and SPM [34][35][36]. And it also has a serious SRS effect because of the temporal instability of the FO seed [37,38].…”

Section: Introductionmentioning

confidence: 99%

Influence of injected signal polarization on SBS, SRS, spectral broadening, and self-pulsing properties in high-power fiber amplifier

Wang¹,

Peng²,

Feng³

et al. 2022

Laser Phys. Lett.

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In this paper, we construct a narrow-linewidth amplifier based on polarization-maintaining (PM) fiber, which can be injected by a fiber oscillator seed or white noise signal phase-modulated seed. The stimulated Brillouin scattering (SBS), SRS, spectral broadening, self-pulsing properties of the fiber amplifier when its’ injected signal is 0° or 45° relative to the slow axes of the PM fiber are studied. It is indicated that when the injected signal is launched at 45° relative to the slow axes, the nonlinear effects are significantly suppressed compared with the case of the injected signal is launched parallel to the slow axis. The spectral broadening rate is reduced from 0.14 pm W−1 to 0.0747 pm W−1, the ratio of Raman to laser peak intensity is increased from 20 dB to 30 dB, the SBS threshold is increased by >24%, and the self-pulsing threshold is increased by 28.7%. It is worth noting that the nonlinear properties corresponding to the injected polarization state in our experiment are quite different from some earlier works.

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Effect of the Number of Longitudinal Modes on Spectral Broadening in a High Power Fiber Amplifier

Cited by 18 publications

References 18 publications

2.5 kW Narrow Linewidth Linearly Polarized All-Fiber MOPA With Cascaded Phase-Modulation to Suppress SBS Induced Self-Pulsing

2.5 kW Narrow Linewidth Linearly Polarized All-Fiber MOPA With Cascaded Phase-Modulation to Suppress SBS Induced Self-Pulsing

A 3.5-kW near-single-mode oscillating–amplifying integrated fiber laser

Influence of injected signal polarization on SBS, SRS, spectral broadening, and self-pulsing properties in high-power fiber amplifier

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