In this paper, the dependence of stimulated Brillouin scattering (SBS) threshold on the sinusoidal modulated properties of pump pulse is studied. A 527-nm-wavelength, 5 ns square laser pulse with sinusoidal temporal modulation is used as the pump source, and a 600 mm liquid heavy fluorocarbon material FC-40 is used as the Brillouin medium. The numerically calculated results indicate that the SBS threshold increases with the increase of both temporal intensity modulation index and modulation frequency of the pump pulse. However, when the intensity distortion criterion is below 30% or the duration of modulation peaks below three times the phonon lifetime, the SBS threshold tends to remain stable. The numerical results provide assistance to judge the SBS threshold for unsmoothed pump pulses, especially for high power laser applications.

中文翻译：

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激发布里渊散射阈值与泵浦强度波动关系的数值研究

本文研究了受激布里渊散射（SBS）阈值对泵浦脉冲的正弦调制特性的依赖性。将具有正弦时间调制的527 nm波长，5 ns方波激光脉冲用作泵浦源，并将600 mm液态重碳氟化合物FC-40用作布里渊介质。数值计算结果表明，SBS阈值随时间强度调制指数和泵浦脉冲调制频率的增加而增加。但是，当强度失真标准低于30％或调制峰值的持续时间低于声子寿命的三倍时，SBS阈值趋于保持稳定。数值结果有助于判断未平滑泵浦脉冲的SBS阈值，特别是在高功率激光应用中。