Zuhlke Craig A, Tsibidis George D, Anderson Troy, Stratakis Emmanuel, Gogos George, Alexander Dennis R
Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH), N. Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece.
AIP Adv. 2018;8(1):015212. doi: 10.1063/1.5020029. Epub 2018 Jan 10.
The hydrodynamic mechanisms associated with the formation of femtosecond laser induced ripples on copper for two angles of incidence are reported. Laser pulse length used for this work is 35 fs. A revised two-temperature model is presented that comprises transient changes of optical characteristics during the irradiation with femtosecond pulses to model relaxation processes and thermal response in bulk copper. The theoretical model takes into account the fluid flow dynamics that result in ripple periods shorter than the wavelength of the surface plasmon polaritons. Theoretical and experimental results are reported for incident angles of 0 and 45 relative to the surface normal. There is agreement between the experimentally measured and the theoretically predicted ripple periodicity for 50 pulses at 0 incidence. By contrast, for 100 pulses at 0 incidence, and 50 and 100 pulses at 45 incidence, the experimentally measured ripples have a larger period than the one predicted by the model while the trends in period with increased incident angle, and increased fluence are in agreement between the experimental and the theoretical results.
报道了与飞秒激光在铜表面以两个入射角诱导产生波纹相关的流体动力学机制。本工作中使用的激光脉冲长度为35飞秒。提出了一种修正的双温度模型，该模型包括飞秒脉冲辐照期间光学特性的瞬态变化，以模拟块状铜中的弛豫过程和热响应。理论模型考虑了导致波纹周期短于表面等离激元极化子波长的流体流动动力学。报道了相对于表面法线入射角为0°和45°时的理论和实验结果。对于入射角为0°的50个脉冲，实验测量的波纹周期与理论预测值一致。相比之下，对于入射角为0°的100个脉冲以及入射角为45°的50个和100个脉冲，实验测量的波纹周期比模型预测的更大，而随着入射角增加和通量增加，周期的变化趋势在实验和理论结果之间是一致的。
