High pulse energy, high average power lasers with low spatial modulation have attracted many advanced applications in scientific research, and beam combination through stimulated Brillouin amplification (SBA) offers the potential for energy scaling with repetitive operation. However, attaining low-modulation beam combining output remains a significant challenge due to the near-field interference induced by the overlapping configuration of multiple pump beams with identical frequencies during the SBA process. Here, the method for reducing spatial modulation intensity via optimizing the structure parameters in the SBA beam combination system is proposed. In the proof-of-principle nine-channel SBA beam combination experiment, a low-modulation near-field output with an M-T value of 1.088 was demonstrated through adjustment, which is nearly identical to the M-T value of the incident Stokes seed. This work introduces a promising methodology for achieving high-pulse energy and high-average power lasers via SBA beam combining techniques, ensuring exceptional beam quality, which have profound implications for petawatt laser pumping, material processing, and laser-matter interaction.

Laser beam combining based on stimulated Brillouin amplification (SBA) promises numerous applications, since it can not only boost the power of the pulsed laser from multi-pump energy transfer but also permit the active spatial intensity manipulation process for the diverse-targeted beam profile, such as a square or round flat-top beam. In this paper, in order to further enhance the output laser beam intensity, a hybrid spatial manipulation method, which combines the structure and beam intensity optimization, has been proposed for the first time, to our knowledge. Based on the simulation results of the SBA beam combining models, a round flat-top combined output with a spatial intensity modulation index of M=1.42 is realized from an initially Gaussian beam profile experimentally. Simultaneously, the peak intensity, from initially 200MW/cm2 to exceeding 1GW/cm2, was obtained in the five-beam-combining system, with the combining efficiency reaching 78.5%. This hybrid manipulation method paved the way for practical application of SBA beam combining systems towards tens-of-joule-level repetitive nanosecond laser pulse output in the field of material processing and petawatt laser pumping, etc.

Burst mode lasers, characterized by a sequence of high-intensity pulses, are integral to applications such as the examination of turbulent flows and optical metrology. This study investigates a 1.5 μm passively Q-switched pulse burst microchip laser, end-pumped by a 940 nm laser diode. Utilizing Er:Yb:glass as the gain medium and Co:MALO for passive Q-switching, delivering a pulse width of 5.5 ms and a repetition rate of 10 Hz. When the initial transmittance of the saturable absorber was 93 % and the maximum absorbed pump energy reached 85 mJ, we successfully generated up to 12, 8, and 4 pulses within a burst at 1.5 μm. These results corresponded to cavity lengths of 12 mm, 13 mm, and 14 mm, respectively. By using a saturable absorber with an initial transmittance of 90.5 %, a higher single pulse energy and a narrower pulse width were realized. The narrowest pulse width was reduced to 6.2 ns, with a corresponding pulse energy of 272 μJ. The peak power in the Er:Yb:glass/Co:MALO pulse burst laser reached an estimated 43.9 kW.This research provides valuable experimental and theoretical insights for the development of human eye-safe lasers with adjustable pulse sequences.

The control of rogue waves in mid-infrared SC generated by pumped femtosecond pulses in chalcogenic optical fibers abnormal dispersion has been studied. And the control effect of the time delay between the seed light and the pump light on the rogue wave in the mid infrared supercontinuum is numerically studied. A seed is emitted into the photonic crystal fiber with an appropriate time delay to control the soliton trajectory. The results show that the appropriate negative time delay will increase the possibility of the formation of rogue waves in the mid-infrared supercontinuum, while the appropriate positive time delay will inhibit the formation of rogue waves. In addition, we also numerically study the influence of the peak power of the pump light on the formation of rogue waves. With the change of peak power, rogue waves will be promoted or suppressed. We believe that this study will provide new insights into the control of rogue waves.