An Improved Two-Temperature Model for Metal Thin Film Heating by Femtosecond Laser Pulses
In femtosecond laser processing of metals, the well-known two-temperature models have been widely used to calculate the photon-electron and electron-lattice interactions and energy transport. However, the estimations of some critical parameters, such as the electron heat capacity and reflectivity, in the models are limited to low fluences and cannot correctly predict the damage threshold without using fitting variables. This paper extends the existing two-temperature models by using quantum treatments for free electrons to calculate the time and space dependent optical and thermal properties, including the electron heat capacity, electron relaxation time, electron conductivity, reflectivity and absorption coefficient. The improved two-temperature model is employed to investigate the heating process of thin gold films until melting occurs, which is assumed to be the initiation of damage. The predicted damage threshold fluences for gold films using the proposed new model are in agreement with published experimental data. The effect of pulse duration on the damage threshold fluence is also studied.
L. Jiang and H. Tsai, "An Improved Two-Temperature Model for Metal Thin Film Heating by Femtosecond Laser Pulses," Proceedings of the 23rd International Congress on Applications of Laser and Electro-Optics (2004, San Francisco, CA), Laser Institute of America, Oct 2004.
23rd International Congress on Applications of Laser and Electro-Optics, ICALEO 2004 (2004: Oct. 4-7, San Francisco, CA)
Mechanical and Aerospace Engineering
Article - Conference proceedings
© 2004 Laser Institute of America, All rights reserved.
07 Oct 2004