Tsibidis George D, Stratakis Emmanuel
Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH), N. Plastira 100, Vassilika Vouton, 70013, Heraklion, Crete, Greece.
Department of Physics, University of Crete, 71003, Heraklion, Greece.
Sci Rep. 2020 May 26;10(1):8675. doi: 10.1038/s41598-020-65613-w.
Irradiation of solids with ultrashort pulses and laser processing in the mid-Infrared (mid-IR) spectral region is a yet predominantly unexplored field with a large potential for a wide range of applications. In this work, laser driven physical phenomena associated with processes following irradiation of fused silica (SiO) with ultrashort laser pulses in the mid-IR region are investigated in detail. A multiscale modelling approach is performed that correlates conditions for formation of perpendicular or parallel to the laser polarisation low spatial frequency periodic surface structures for low and high intensity mid-IR pulses (not previously explored in dielectrics at those wavelengths), respectively. Results demonstrate a remarkable domination of tunneling effects in the photoionisation rate and a strong influence of impact ionisation for long laser wavelengths. The methodology presented in this work is aimed to shed light on the fundamental mechanisms in a previously unexplored spectral area and allow a systematic novel surface engineering with strong mid-IR fields for advanced industrial laser applications.
用超短脉冲对固体进行辐照以及在中红外（mid - IR）光谱区域进行激光加工，是一个尚未得到充分探索的领域，具有广泛应用的巨大潜力。在这项工作中，详细研究了与在中红外区域用超短激光脉冲辐照熔融石英（SiO）后发生的过程相关的激光驱动物理现象。采用了一种多尺度建模方法，该方法分别关联了低强度和高强度中红外脉冲（在那些波长下，电介质中此前尚未探索过）形成与激光偏振垂直或平行的低空间频率周期性表面结构的条件。结果表明，在光电离速率中隧道效应占显著主导地位，并且对于长激光波长，碰撞电离有很强的影响。这项工作中提出的方法旨在揭示一个此前未探索光谱区域的基本机制，并允许利用强中红外场进行系统的新型表面工程，以用于先进的工业激光应用。
