kW-level, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme

Abstract

In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode-multimode-single-mode structure seed laser, a linearly polarized Yb-doped fiber laser with narrow linewidth and high output power is achieved. This laser, when used as a master oscillator, can be capable of suppressing the ASE in the process of power amplification. Thus, only one-stage amplification structure is used to scale up the laser power, and linearly polarized output with a polarization extinction ration of 14 dB, a narrow linewidth of 0.3 nm and an output power of 1018 W are achieved. Moreover, due to the good beam quality of seed laser and the well-designed amplifier stage, the beam quality of the output laser is near-diffraction-limited with M 2x ∼ 1.18 and M 2 y ∼ 1.24 at the maximum power, and without mode instability occurring.

All-fiberized and narrow-linewidth 5 kW power-level fiber amplifier based on a bidirectional pumping configuration

“…High-power narrow-linewidth fiber lasers with excellent beam quality have been highly desired for spectral and coherent beam combinations [1][2][3]. The power scaling of single-mode narrow-linewidth fiber lasers has been under intense investigations [4][5][6][7][8][9][10][11][12][13][14][15]. This mainly involves comprehensive suppressions of the transverse mode instabilities (TMI) and nonlinear inelastic scattering effects, such as stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) [16][17][18].…”

“…It should be noted that those two fiber laser systems are established in free-space structure, which is not suitable for compact assembling and maintenance. Therefore, most of the reported all-fiberized narrow-linewidth fiber amplifiers are based on conventional active fiber and require comprehensive optimization of structure and parameters of the fiber amplifiers [7][8][9][10][11][12][13][14][15]. As for all-fiberized format, 3.7 kW output power had been achieved with near diffraction limited beam quality and spectral linewidth of ~ 0.3 nm [15].…”

Seeding High Brightness Fiber Amplifiers With Multi-Phase Coded Signal Modulation for SBS Effect Management

“…As for SBS effect, several suppressing techniques have been proposed, such as selecting large mode area, short active fibers [18,19], applying thermal or stress gradients [20][21][22][23], acoustic tailoring techniques [24,25], multilongitudinal-mode (MLM) fiber oscillator [26], multi-tone injection [27,28] and phase modulation [29][30][31][32][33][34]. Among all of them, phase modulation technique is a simple and robust approach to mitigate SBS effect and control the linewidth of fiber amplifiers to promise an excellent temporal coherence [35].…”

In-band pumping avenue based high power superfluorescent fiber source with record power and near-diffraction-limited beam quality

“…Although previous investigations have announced that hundred-watt-level high power SFS can be achieved in a single-stage structure with careful system parameters design, the further power enhancement is still a challenge because of the physical parasitic lasing issue. What is more, the presented high power SFSs in single-stage structure were often broadband and randomlypolarized [16][17][18][19] , while narrowband and polarization characteristics are required in practical applications [20,21] . Fortunately, employing master-oscillator-power-amplifier (MOPA) configuration can introduce a new horizon of high power SFS and leverage the high power SFS with special spectrum/polarization characteristics [22][23][24][25] and kilowatts operating power [26][27][28][29][30] .…”