The effects of turbulence intensity and turbulence region on the distribution of femtosecond laser filaments are experimentally elaborated. Through the ultrasonic signals emitted by the filaments, it is observed that increasing turbulence intensity and an expanding turbulence active region cause an increase in the start position of the filament and a decrease in filament length, which can be well explained by theoretical calculation. It is also observed that the random perturbation of the air refractive index caused by atmospheric turbulence expands the spot size of the filament. Additionally, when the turbulence refractive index structure constant reaches 8.37×10-12m-2/3, multiple filaments are formed. Furthermore, the standard deviation of the transverse displacement of filament is found to be proportional to the square root of the turbulent structure constant under the experimental turbulence parameters in this paper. These results contribute to the study of femtosecond laser propagation mechanisms in complex atmospheric turbulence conditions.

对高能量掺镱激光器进行腔外压缩，是获得高能量少数周期脉冲的重要方式。通过数值模拟研究了单脉冲能量为250 mJ，波长为1 030 nm的高能量掺镱激光器通过固体多薄片介质进行非线性脉冲压缩的过程，及介质周期、厚度对频谱展宽的影响。在优化频谱展宽条件的过程中发现，不超过介质损伤阈值的情况下，固体薄片组的周期和厚度对频谱展宽具有正向影响。通过选取合适的介质厚度及周期，激光频谱通过熔融石英介质进行展宽，最终输出的光谱带宽达229 nm，补偿色散后，激光脉冲由500 fs压缩至16.2 fs，压缩比达到30。研究结果为实现高能量激光脉冲的非线性压缩提供了理论参考。

The spatial distribution of the forward-propagating amplified spontaneous emission (ASE) of nitrogen molecular ions during femtosecond laser filamentation in air is studied via numerical simulations. The results suggest that the divergence angle and signal intensity are extremely sensitive to the external focal length. Concurrently, we show that the optical Kerr effect plays a significant role in concentrating the directivity of ASE signals, particularly in cases of loose focusing. Furthermore, the simulations demonstrate that ASE signals are enhanced for a tight focus, although the corresponding filament length is shorter. The main physical mechanism underlying this process is the competition between the plasma defocusing and optical Kerr effects. The result is important for filamentation-based light detection and ranging applied to remote sensing.