Effect of laser intensity on temporal and spectral features of laser generated acoustic shock waves: ns versus ps laser pulses.
Effect of laser intensity on temporal and spectral features of laser generated acoustic shock waves: ns versus ps laser pulses.
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DOI：
10.1364/ao.56.006902
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发表时间：
2017-08
期刊：
影响因子：
1.9
通讯作者：
E. Manikanta;L. Vinoth Kumar;C. Leela;P. Prem Kiran
中科院分区：
文献类型：
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作者：
E. Manikanta;L. Vinoth Kumar;C. Leela;P. Prem Kiran
研究了纳秒（ns）和皮秒（ps）激光在不同入射强度下对大气的击穿过程中产生的声冲击波（ASW）特性的演化规律。通过改变ns和ps脉冲的焦点几何形状来改变强度。ASW的压力观察到遵循等离子体密度和等离子体物种的重组之间的动态相互作用。激光能量到声能的转换已经从松散聚焦条件增加到紧密聚焦条件。对于ns-LIB（76-48 kHz）和ps-LIB（111.2-92.1 kHz），中心频率随着激光强度的增加而向较低侧移动。声发射的角分布，观察到以下的激光诱导等离子体火花在ns和ps-LIB。
Evolution of acoustic shock wave (ASW) properties generated during nanosecond (ns) and picosecond (ps) laser-induced breakdown (LIB) of atmospheric air at different input intensities is presented. The intensity is varied by changing the focal geometry of ns and ps pulses. The ASW pressures are observed to follow the dynamic interplay between the plasma density and recombination of plasma species. The conversion of laser energy to acoustic energy has increased from loose to tight focusing conditions. The central frequencies have moved toward the lower side with increasing laser intensities for both ns-LIB (76-48 kHz) and ps-LIB (111.2-92.1 kHz). The angular distribution of acoustic emissions was observed to follow the laser-induced plasma spark in both ns- and ps-LIB.