scholarly journals Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 14
Author(s):  
Tao Feng ◽  
Gong Chen ◽  
Hainian Han ◽  
Jie Qiao
Keyword(s):  
Femtosecond Laser ◽  
Stable State ◽  
Femtosecond Laser Ablation ◽  
Drude Model ◽  
Temperature Model ◽  
Plasma Generation ◽  
High Fluences ◽  
Microscopy Technique ◽  
Wide Range ◽  
Two Temperature

The dynamics of ablation in monocrystalline silicon, from electron-hole plasma generation to material expansion, upon irradiation by a single femtosecond laser pulse (1030 nm, 300 fs pulse duration) at a wide range of fluences is investigated using a time-resolved microscopy technique. The reflectivity evolution obtained from dynamic images in combination with a theoretical Drude model and a Two-Temperature model provides new insights on material excitation and ablation process. For all fluences, the reflectivity increased to a temporary stable state after hundreds of femtoseconds. This behavior was predicted using a temperature-dependent refractive index in the Drude model. The increase in velocity of plasma generation with increasing fluence was theoretically predicted by the Two-Temperature model. Two ablation regimes at high fluences (>0.86 J/cm2) were identified through the measured transient reflectivity and ablation crater profile. The simulation shows that the fluence triggering the second ablation regime produces a boiling temperature (silicon, 2628 K).

scholarly journals Simulation of laser ablation of metals for nanoparticles production

2016 ◽  
Vol 41 ◽  
pp. 1660143 ◽  
Author(s):  
R. V. Davydov ◽  
V. I. Antonov ◽  
T. I. Davydova
Keyword(s):  
Experimental Data ◽  
Laser Ablation ◽  
Femtosecond Laser Ablation ◽  
Hydrodynamic Equations ◽  
Temperature Model ◽  
Wide Range ◽  
Simulation Results ◽  
Range Equation ◽  
Two Temperature ◽  
Good Agreement

In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.

scholarly journals Improved two-temperature model and its application in femtosecond laser ablation of metal target

2010 ◽  
Vol 28 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Ranran Fang ◽  
Duanming Zhang ◽  
Hua Wei ◽  
Zhihua Li ◽  
Fengxia Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Fluence ◽  
Femtosecond Laser Ablation ◽  
Temperature Model ◽  
Metal Target ◽  
Temperature Dependent ◽  
Two Temperature

AbstractAn improved two-temperature model to describe femtosecond laser ablation of metal target was presented. The temperature-dependent heat capacity and thermal conductivity of the electron, as well as electron temperature-dependent absorption coefficient and absorptivity are all considered in this two-temperature model. The tailored two-temperature model is solved using a finite difference method for copper target. The time-dependence of lattice and electron temperature of the surface for different laser fluence are performed, respectively. The temperature distribution of the electron and lattice along with space and time for a certain laser fluence is also presented. Moreover, the variation of ablation rate per pulse with laser fluence is obtained. The satisfactory agreement between our numerical results and experimental data indicates that the temperature dependence of heat capacity, thermal conductivity, absorption coefficient and absorptivity in femtosecond laser ablation of metal target must not be neglected. The present model will be helpful for the further experimental investigation of application of the femtosecond laser.

Investigation of Femtosecond Laser Ablation Threshold for Nickel Template

2014 ◽  
Vol 633-634 ◽  
pp. 665-670 ◽  
Author(s):  
Lei Zhang ◽  
Xiao Wen Cao ◽  
Shun Guang Li ◽  
Ru Yi Xiang ◽  
Hui Chao Sun
Keyword(s):  
Femtosecond Laser ◽  
Ablation Threshold ◽  
Femtosecond Laser Ablation ◽  
Target Surface ◽  
Single Pulse ◽  
Normal Incidence ◽  
Objective Lens ◽  
Temperature Model ◽  
Two Temperature ◽  
Single Pulse Ablation

This paper presents a theoretical and experimental investigation into the ablation threshold of nickel template by femtosecond laser in air at atmospheric pressure. The laser pulses used for the study are 800 nm in wavelength, 100fs in pulse duration, and 1KHz in repetition rate. The two-temperature model is used to predict the single-pulse ablation threshold for nickel theoretically. Micro-hole ablation experiments are carried out in air by focusing the femtosecond laser beam on the nickel target surface at normal incidence with the long-focus objective lens of enlargement factor 50 and NA=0.7 to determine the single-pulse and multi-pulse ablation thresholds for nickel by setting up the relationship between the measured hole diameters and the pulse energies. The single pulse ablation threshold of 4132.98 Jm-2obtained experimentally is very close to that of 3907.99 Jm-2predicted by two-temperature model. The incubation factorξ, which describes the changes of the multi-pulse ablation thresholds with the number of pulses, is determined to be 0.812 for nickel.

Multiscale Investigation of Thickness Dependent Melting Thresholds of Nickel Film Under Femtosecond Laser Heating

2018 ◽  
Author(s):  
Pengfei Ji ◽  
Mengzhe He ◽  
Yiming Rong ◽  
Yuwen Zhang ◽  
Yong Tang
Keyword(s):  
Molecular Dynamics ◽  
Femtosecond Laser ◽  
Multiscale Simulation ◽  
Nickel Film ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Model Description ◽  
Temperature Model ◽  
Laser Material Processing ◽  
Two Temperature

A multiscale modeling that integrates electronic scale ab initio quantum mechanical calculation, atomic scale molecular dynamics simulation, and continuum scale two-temperature model description of the femtosecond laser processing of nickel film at different thicknesses is carried out in this paper. The electron thermophysical parameters (heat capacity, thermal conductivity, and electron-phonon coupling factor) are calculated from first principles modeling, which are further substituted into molecular dynamics and two-temperature model coupled energy equations of electrons and phonons. The melting thresholds for nickel films of different thicknesses are determined from multiscale simulation. Excellent agreement between results from simulation and experiment is achieved, which demonstrates the validity of modeled multiscale framework and its promising potential to predict more complicate cases of femtosecond laser material processing. When it comes to process nickel film via femtosecond laser, the quantitatively calculated maximum thermal diffusion length provides helpful information on choosing the film thickness.

Materials Removals During Femtosecond Laser Non-Thermal Ablation of Dielectrics

2006 ◽  
Author(s):  
Lan Jiang ◽  
Hai-Lung Tsai
Keyword(s):  
Experimental Data ◽  
Laser Ablation ◽  
Femtosecond Laser ◽  
Electron Density ◽  
Free Electron ◽  
Femtosecond Laser Ablation ◽  
Threshold Fluence ◽  
Plasma Model ◽  
Free Electron Density ◽  
Two Temperature

It remains a big challenge to theoretically predict the material removals mechanism in femtosecond laser ablation. To bypass this unresolved problem, many calculations of femtosecond laser ablation of non-metals have been based on free electron density distribution without the actual consideration of the phase change mechanism. However, this widely-used key assumption needs further theoretical and experimental confirmations. By combining the plasma model and improved two-temperature model developed by the authors, this study focuses on investigating ablation threshold fluence, depth, and shape during femtosecond laser ablation of dielectrics through non-thermal processes (the Coulomb explosion and electrostatic ablation). The predicted ablation depths and shapes in fused silica, by using 1) the plasma model only and 2) the plasma model plus the two-temperature equation, are both in agreement with published experimental data. The widely-used assumptions for threshold fluence, ablation depth, and shape in the plasma model based on free electron density are validated by the comparison study and experimental data.

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