High-power cylindrical vector beams generated from an all-fiber linearly polarized laser by metasurface extracavity conversion.

Five-hundred-watt cylindrical vector beams (CVBs) at 1030 nm with the 3 dB linewidth being less than 0.25 nm have been generated from a narrow linewidth all-fiber linearly polarized laser by metasurface extracavity conversion. At maximum output power, the transmission efficiency and polarization extinction ratio of radially polarized cylindrical vector beams (RP-CVBs) are beyond 98% and 95%, respectively.

SRS suppression in multi-kW fiber lasers with a multiplexed CTFBG.

In this paper, we present experimental studies on newly developed multiplexed chirped tilted fiber Bragg gratings (MCTFBGs) for stimulated Raman scattering (SRS) suppression for high-power fiber laser systems. The MCTFBG device is composed of five continuous segments of chirped tilted fiber Bragg gratings (CTFBGs), which are inscribed into the large-mode-area (LMA, 25/400μm) fibers. The SRS suppression capability of the MCTFBG device has been successfully demonstrated with a master oscillator power amplification (MOPA) fiber laser system at the output level of 3.

Experimental investigation of quasi-static mode degradation in a high power large mode area fiber amplifier.

In this work, quasi-static mode degradation in high power fiber amplifiers has been investigated experimentally. An increase of M from 1.3 to 2.

3 kW high OSNR 1030 nm single-mode monolithic fiber amplifier with a 180 pm linewidth.

In this Letter, the amplified spontaneous emission (ASE) effect of a 1030 nm fiber laser is studied theoretically and, based on the theoretical results, a 3 kW high optical signal-to-noise ratio (OSNR) 1030 nm fiber amplifier with a 180 pm linewidth and near-diffraction-limited beam quality is achieved. A theoretical model, which takes simulate ASE light falling in the range of Raman light as the Raman seed, has been used to optimize the power scaling capability of 1030 nm fiber amplifiers. It shows that the SRS effect seeded by the ASE is the main limiting factor for the fiber amplifiers operating at 1030 nm, and >3 output power with a high OSNR can be achieved by proper parameter designing of the fiber laser system.

Experimental study of the influence of mode excitation on mode instability in high power fiber amplifier.

Mode instability with different mode excitation has been investigated by off-splicing the fusion point in a 4 kW-level monolithic fiber laser system, which reveals that the fiber systems exciting more high order mode content exhibits lower beam quality but higher mode instability threshold. The static-to-dynamic mode degradation and dynamic-only mode degradation have also been observed in the same high power fiber amplifier by varying the mode excitation, which implicates that the mode excitation plays an important role in mode characteristics in high power fiber lasers. By employing a seed with near fundamental mode beam quality, only dynamic mode degradation-mode instability sets in with negligible static beam quality degradation.

kW-level 1030 nm polarization-maintained fiber laser with narrow linewidth and near-diffraction-limited beam quality.

kW-level 1030 nm polarization-maintained fiber laser with narrow linewidth and near-diffraction-limited beam quality is demonstrated. Theoretical simulations based on the power balance equation are first performed to optimize the system parameters of the 1030 nm ytterbium-doped fiber laser for the maximum suppression of amplified spontaneous emission (ASE). With the optimized parameters, both the copumped and counterpumped MOPA lasers are implemented to obtain an output power of >1  kW.