Temporal and spectral resolved ultrafast ellipsometry and simulation of transient states of matter during laser ablation

时间和光谱分辨超快椭偏仪以及激光烧蚀过程中物质瞬态的模拟

• 批准号: 273381511
• 负责人: Professor Dr. Heinz Paul Huber
• 金额: --
• 依托单位: Laserzentrum Hochschule München (LHM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/273381511?language=en
• 关键词: Temporal; spectral; resolved; ultrafast; ellipsometry

The direct and induced (confined) laser ablation of materials and thin film systems with ultrashort laser pulses enables high-precision material processing in a variety of industrial applications such as drilling of injection nozzles, cutting of hardened glass displays or selective patterning of thin film solar cells and OLEDs (organic light emitting diodes).From literature numerous studies are known how to optimize the ablation efficiency of direct ablation of various materials. Depending on the material, fs- or ps-pulses show a higher ablation efficiency, but there is no clear explanation for this behaviour. Our simulations and transient reflectivity measurements indicate that both the electron diffusion length, which defines the heat deposition, and the change in absorbance during the irradiation depend on the pulse duration.For the induced ablation, the irradiated material is confined by a transparent layer. The material is removed by a lift-off of an intact disc of the layer system. This enables very precise and very energy efficient laser processing far below the thermodynamic limit.Our investigations of the driving ablation mechanisms suggest that shock waves, which are generated on ultrafast time scales, initiate the material transport or removal in the nanosecond range. The shock waves could be generated in the solid and / or liquid phase by ultrafast heating and expansion, and not in the gas or plasma phase, as observed for nanosecond pulses.In order to get a better understanding of the transient behaviour during the direct and induced ablation, detailed time- and space resolved investigations of the heating, the phase transitions and the optical properties (reflection and absorption) of the irradiated material are necessary especially in the low ps time regime.These investigations are part of the project and will be performed by measuring the complex refractive index with pump-probe ellipsometry in combination with multi-physics and multi-scale modelling for various materials. Thus, a well-founded model of processes on ultrafast time scales shall be developed.The model shall then be used to answer fundamental application-related questions of the direct and induced ablation, such as the question of the optimal laser parameters (pulse width, wave length, fluence, beam diameter) for most efficient processing of various materials, the problem of the maximum repetition rate, the connection between pulse duration and ablation rate, or the influence of the beam diameter on the induced laser ablation. In this way, the results of the project will be used for the optimization of industrially relevant laser processes.

使用超短激光脉冲对材料和薄膜系统进行直接和诱导（受限）激光烧蚀，可在各种工业应用中实现高精度材料加工，例如注射喷嘴钻孔、硬化玻璃显示器切割或薄膜太阳能电池和 OLED（有机发光二极管）的选择性图案化。从文献中可以了解到，如何优化各种直接烧蚀的烧蚀效率 材料。根据材料的不同，飞秒脉冲或皮秒脉冲显示出更高的烧蚀效率，但对此行为没有明确的解释。我们的模拟和瞬态反射率测量表明，定义热沉积的电子扩散长度和照射期间吸光度的变化都取决于脉冲持续时间。对于诱导烧蚀，被照射的材料受到透明层的限制。通过剥离分层系统的完整圆盘来去除材料。这使得远低于热力学极限的非常精确和非常节能的激光加工成为可能。我们对驱动烧蚀机制的研究表明，在超快时间尺度上产生的冲击波会引发纳秒范围内的材料传输或去除。冲击波可以通过超快加热和膨胀在固相和/或液相中产生，而不是在纳秒脉冲中观察到的气相或等离子体相。为了更好地理解直接和诱导烧蚀期间的瞬态行为，需要对受辐射材料的加热、相变和光学特性（反射和吸收）进行详细的时间和空间分辨研究，特别是在 这些研究是该项目的一部分，将通过使用泵浦探针椭圆光测量法测量复折射率并结合多种材料的多物理场和多尺度建模来进行。因此，应开发一个基础良好的超快时间尺度上的加工模型。然后，该模型将用于回答直接烧蚀和诱导烧蚀的基本应用相关问题，例如最有效地加工各种材料的最佳激光参数（脉冲宽度、波长、注量、光束直径）的问题、最大重复率的问题、脉冲持续时间和烧蚀率之间的联系或光束的影响 诱导激光烧蚀的直径。这样，该项目的结果将用于优化工业相关的激光工艺。

项目成果

Early Stage Material Motion and Transient Optical Properties of Metals after Ultrashort Laser Pulse Irradiation

超短激光脉冲照射后的早期材料运动和金属的瞬态光学性质

• DOI: 10.2961/jlmn.2019.01.0002
• 发表时间: 2019
• 期刊: Journal of Laser Micro/Nanoengineering
• 作者: C. McDonnell;J. Winter;S. Rapp;H.P. Huber;M. Schmidt
• 通讯作者: M. Schmidt

Ultrafast pump-probe ellipsometric measurements of transient optical properties in metals during laser ablation

激光烧蚀过程中金属瞬态光学特性的超快泵浦探针椭圆测量

• DOI: 10.1109/cleoe-eqec.2017.8087227
• 发表时间: 2017
• 期刊: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
• 作者: S. Rapp;J. Winter;H. P. Huber;M. Schmidt
• 通讯作者: M. Schmidt

Ultrafast laser processing of copper: A comparative study of experimental and simulated transient optical properties

• DOI: 10.1016/j.apsusc.2017.02.070
• 发表时间: 2017-09-30
• 期刊: APPLIED SURFACE SCIENCE
• 影响因子: 6.7
• 作者: Winter, Jan;Rapp, Stephan;Huber, Heinz P.
• 通讯作者: Huber, Heinz P.

Ultrafast pump-probe ellipsometry setup for the measurement of transient optical properties during laser ablation.

• DOI: 10.1364/oe.24.017572
• 发表时间: 2016-08
• 期刊: Optics express
• 影响因子: 3.8
• 作者: S. Rapp;Michael Kaiser;Michael Schmidt;H. Huber

Optical dynamics in ultra-short laser pulse irradiated copper revealed by simulation and experimental measurement with time-resolved pump-probe ellipsometry

通过时间分辨泵浦探针椭圆光度法的模拟和实验测量揭示了超短激光脉冲照射铜的光学动力学

• DOI: 10.1109/cleoe-eqec.2017.8087226
• 发表时间: 2017
• 期刊: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
• 作者: J. Winter;S. Rapp;H. P. Huber;Michael Schmidt
• 通讯作者: Michael Schmidt