Effect of repetition rate on ultrashort pulse laser propagation and energy deposition
Effect of repetition rate on ultrashort pulse laser propagation and energy deposition
复制标题
重复率对超短脉冲激光传播和能量沉积的影响
DOI：
10.1117/12.3016318
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发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Penano, Joseph R.
中科院分区：
文献类型：
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作者：
Pena, Jessica;Rosenthal, Eric W.;Englesbe, Alexander;Isaacs, Joshua;Helle, Michael;Penano, Joseph R.
现代超短脉冲激光器(USPL)的发展正朝着更高的重复频率和更高的平均功率系统发展。高峰值功率、低重复频率的USPLs长期以来一直被用来产生激光细丝，它由一个等离子体通道和聚焦的高强度传输区组成。丝化会导致线性和非线性效应导致空气中的热沉积，产生在流体动力学时间尺度(毫秒)内持续的气体密度降低。这是在飞秒脉冲过去很久之后。在“单脉冲”(大约10赫兹)的成丝方式中，脉冲之间的时间允许空气密度在下一个脉冲到达之前恢复到平衡。先前的工作已经通过干涉测量法实验测量了单次脉冲的气体密度下降，并证明了高重复频率成丝会由于先前脉冲的残余加热而导致后续脉冲的偏转。这项工作实验研究了USPL热晕作为激光重复频率的函数。通过测量激光灯丝的能量沉积，验证了脉冲间的残余加热效应。时间和空间分辨的能量沉积是从由气体密度降低引起的相移的干涉测量中提取的。将实验结果与模型结果进行了比较，并对已有的结果进行了验证。这项工作展示了现代高平均功率、高重复频率USPL脉冲的大气传输与传统的单次激发USPL系统的不同之处。
Modern USPL (Ultra Short Pulse Laser) development is trending towards higher repetition rates and higher average power systems. High peak power, low repetition rate USPLs have long been used to generate laser filaments, which consist of a plasma channel and region of focused high intensity propagation. Filamentation leads to heat deposition in the air from linear and nonlinear effects, producing a gas density depression that persists over hydrodynamic timescales (milliseconds). This is long after the femtosecond pulse has passed. In the “single shot” (approximately 10 Hz) regime of filamentation, the time between pulses allows the air density to return to equilibrium before the next pulse arrives. Prior work has experimentally measured the single shot gas density depression via interferometry and demonstrated that high repetition rate filamentation leads to deflection of subsequent pulses due to residual heating from the prior pulses. This work experimentally examines USPL thermal blooming as a function of laser repetition rate. Residual heating effects between pulses are demonstrated through measurements of the energy deposition by the laser filament. The temporally and spatially resolved energy deposition is extracted from interferometric measurements of the phase shift due to the gas density depression. Comparison is made between experimentation and modeling, as well as verification of past results. This work demonstrates how atmospheric propagation of modern high average power, high repetition rate USPL pulses differ from traditional single shot USPL systems.