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

Abstract

In this paper, an all-fiberized and narrow-linewidth 5 kW power-level fiber amplifier is presented. The laser is achieved based on the master oscillator power amplification (MOPA) configuration, in which the phase-modulated single-frequency laser is applied as the seed laser and bidirectional pumping configuration is applied in the power amplifier. The stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and transverse mode instability (TMI) effects are all effectively suppressed in the experiment. Consequently, the output power is scaled up to 4.92 kW with a slope efficiency of as high as ~ 80%. The 3 dB spectral width is about 0.59 nm, and the beam quality is measured to be M 2 ~ 1.22 at maximum output power. Furthermore, we have also conducted detail spectral analysis on the spectral width of the signal laser, which reveals that the spectral wing broadening phenomenon could lead to the obvious decrease of the spectral purity at certain output power. Overall, this work could provide a well reference for obtaining and optimizing high-power narrow-linewidth fiber lasers.

High‐Power Laser Systems

“…[364,365] The coiled active fiber of YDF 20/400 under bidirectional pumped MOPA configuration has achieved a narrow linewidth SM 4.92 kW output at 1071 nm by 976 nm pumping. [366] and the SM power scaled to 6 kW with a larger size fiber of YDF 25/400 by 981nm pumping. [340] However, it is easy to cause partial overheating by pouring a large amount of core laser into the cladding through the tapered end cone.…”

Six kilowatt record all-fiberized and narrow-linewidth fiber amplifier with near-diffraction-limited beam quality

“…In those two beam combination systems, high-power singlemode fiber lasers with narrow-linewidth are the crucial units. Nevertheless, the power scaling of narrow-linewidth fiber lasers always lags behind that of broad-linewidth fiber lasers [12][13][14][15][16][17] , because extra design is required to maintain narrow-linewidth operation. Furthermore, recent experimental results reveal that narrower signal bandwidth generally means a lower TMI threshold for the same fiber amplifier [18] .…”

3.96 kW All-Fiberized Linearly Polarized and Narrow Linewidth Fiber Laser with Near-Diffraction-Limited Beam Quality

“…Normally, the methods of generating narrow linewidth laser seeds mainly include: narrow linewidth laser diode [ 9 , 10 ], multi-longitudinal-mode fiber oscillator [ 11 , 12 , 13 ], filtered superfluorescent source [ 14 , 15 , 16 ], and phase modulated single-frequency laser [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Among them, phase modulation has been proved to be a preferable method to acquire narrow linewidth high power fiber laser without obvious spectral broadening and high SRS threshold [ 17 , 18 , 19 ].…”