Abstract
An all-fiberized high-average-power narrow linewidth ns pulsed laser with linear polarization is demonstrated. The laser system utilizes a typical master oscillator power amplifier (MOPA) configuration. The stimulated Brillouin scattering (SBS) is effectively suppressed due to the short fiber length and large mode area in the main amplifier, combined with the narrow pulse duration smaller than the phonon lifetime of SBS effect. A maximal output power of 466 W is obtained with a narrow linewidth of ${\sim}$203.6 MHz, and the corresponding slope efficiency is ${\sim}$80.3%. The pulse duration is condensed to be ${\sim}$4 ns after the amplification, corresponding to the peak power of 8.8 kW and the pulse energy of $46.6~\unicode[STIX]{x03BC}\text{J}$. Near-diffraction-limited beam quality with an $M^{2}$ factor of 1.32 is obtained at the output power of 442 W and the mode instability (MI) is observed at the maximal output power. To the best of our knowledge, this is the highest average output power of the all-fiberized narrow linewidth ns pulsed fiber laser with linear polarization and high beam quality, which is a promising source for the nonlinear frequency conversion, laser lidar, and so on.
Highlights
Nanosecond fiber lasers have attracted much research interest in recent years due to advantages of relatively low cost and flexible operation window compared with their Q-switched solid-state counterparts
We demonstrate an all-fiberized highaverage-power narrow linewidth ns pulsed laser with linear polarization, based on master oscillator power amplifier (MOPA) configuration comprising an externally modulated ns seed and four-stage amplifiers
Near-diffraction-limited beam quality with an M2 factor of 1.32 is obtained at the output power of 442 W and the mode instability (MI) is observed at the maximal output power
Summary
Nanosecond fiber lasers have attracted much research interest in recent years due to advantages of relatively low cost and flexible operation window compared with their Q-switched solid-state counterparts. The most common method to obtain ns fiber laser is the Q-switched regime that is based on various saturation absorbers[12, 13], nonlinear effect[14], acoustic–optical modulator (AOM)[15], stress-induced birefringence[16], tilted fiber grating [17] and direct pump modulation[18, 19], and so on. Another important approach is the external modulation of a continuous wave (CW) laser[20,21,22,23]. Due to large mode area and relatively short required fiber length that benefits the suppression of the nonlinear effects and the spectral broadening, the conventional large-mode-area (LMA) double cladding fiber with high doping concentration is a promising candidate for forming all-fiber structures to obtain high output power in a wide duration range from the nanosecond to the femtosecond[31,32,33], especially for the narrow linewidth output
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