A fundamental study of the interaction of ultrashort pulses and metal will be useful for predicting the ablation morphology and optimizing the process parameters. To study the ultrashort laser pulse interaction on gold, a set of coupled partial differential equations of the two-temperature model was solved in the spatial and time domains with dynamic optical properties and phase explosion mechanism. In an extended Drude model which also takes into account inter-band transitions, the reflectivity and absorption coefficient are contemplated based on the electron relaxation time. The laser energy deposition and phase explosion ablation mechanism are analyzed in the case of succession of laser pulses on the gold with experimental results for fundamental wavelength 1030 nm and fluence ranging from 3 J/cm2 to 18 J/cm2. Electron-lattice thermal relaxation time and separation time are important factors for multi-pulse laser ablation and have been studied. The simulation results demonstrate that by increasing the number of pulses with a shorter separation time compared to electron-lattice thermal relaxation time, lattice temperature can be considerably increased without a noticeable increase in ablation depth. In the study of multiple pulses femtosecond laser ablation, the computational model indicates that succession of laser pulses with a pulse separation time of 50 ps or longer can significantly boost the ablation rate at the same laser fluence. Thus, the deviation from experimental and simulation results gives rise to the conclusion that temporal pulse manipulation with separation time greater than the electron-lattice relaxation time is a useful technique for increasing ablation rate in industrial fast femtosecond laser processing.
Ultra-short laser material processing has received much attention due to the broad applications across nearly all manufacturing sectors. Ultra-short laser ablation is a complex phenomenon involving laser energy spatial distribution, energy absorption on the irradiated surface, transient changes in optical response, and ablation. In order to determine the ablation characteristics and performance, a fundamental study of the interaction between ultra-short laser pulses and the material will be valuable. A theoretical analysis of ultra-short laser-matter interaction can be represented by the two-temperature model which describes the temperature of the electron or carrier and lattice in non-equilibrium conditions when ultra-short laser pulses are applied. During ultrafast irradiation, due to peculiarities between the metal energy absorption to in contrast to semiconductor, a comparative study of silicon and gold ablation mechanism presented. A 2D axial symmetry simulated ablation profiles were compared with the experimental result at fluence ranging from 1 J/cm2 to 9 J/cm2 at the wavelength of 515 nm and 180 fs laser on the silicon and gold sample. The concordance between model calculations and experimental data demonstrates that fs laser ablation of silicon is thermal in nature in a low fluence regime, whereas it is non-thermal in a high-fluence regime. On the other hand, the phase explosion mechanism is prevalent to understand the ablation characteristics of gold with fs pulses. Fundamental information such as the time evolution of the carrier density in silicon, carrier or electron temperature evolution, and lattice temperature evolution can be obtained from the simulation results.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.