In recent decades, ultrafast lasers have been used successfully to micro-machine fused silica. The high intensity laser pulses first excite valence electrons to the conduction band via photoionization and avalanche ionization. The excited free electrons absorb laser energy, and transfer its energy to the ions, resulting in the temperature rise. This ionization leads to significant changes in Coulomb forces among the atoms. Both thermal and non-thermal (Coulomb explosion) ablation processes have been discussed in the literature [1]. This work applies molecular dynamics technique to study the interaction between ultrafast laser pulses and fused silica and the resulting ablation. The main goal of this work is to investigate the ultrafast laser ablation process of fused silica, and to reveal the mechanisms leading to the material's removal. In this MD simulation, the equilibrium state of fused silica is first established at 300 K, and the laser heating and material removal processes are simulated. The ionization of the material and the energy coupling between the laser beam and free electrons and ions are considered. Thermal and non-thermal mechanisms of fused silica ablation are discussed based on calculation results.

1.
Stoian
R.
,
Rosenfeld
A.
,
Ashkenasi
D.
,
Hertel
I. V.
,
Bulgakova
N. M.
and
Campbell
E. E. B.
,
2002
, “
Surface charging and impulsive ion ejection during ultrashort pulsed laser ablation
Phys. Rev. Lett.
,
88
,
0976031
0976034
.
2.
Zhigilei
L. V.
,
2003
, “
Dynamics of the plume formation and parameters of the ejected clusters in short-pulsed laser ablation
”,
Appl. Phys. A
,
76
, pp.
339
50
.
3.
Cheng
C.
and
Xu
X.
,
2005
, “
Mechanisms of decomposition of metal during femtosecond laser ablation
”,
Phys. Rev. B
,
72
, pp.
1654151
16541515
.
4.
Van Beest
B. W. H.
,
Kramer
G. J.
, and
van Santen
R. A.
,
1990
, “
Force fields for silicas and aluminophosphates based on ab initio calculations
”,
Phys. Rev. Lett.
,
64
, pp.
1955
1958
.
5.
Guissani
Y.
and
Guillot
B.
,
1996
, “
A numerical investigation of the liquid-vapor coexistence curve of silica
”,
J. Chem. Phys.
,
104
, pp.
7633
7644
6.
Wu
A. Q.
,
Chowdhury
I. H.
, and
Xu
X.
,
2005
, “
Femtosecond laser absorption in fused silica: Numerical and experimental investigation
”,
Phys. Rev. B
,
72
, pp.
0851281
0851287
.
7.
Vollmayr
K.
,
Kob
W.
, and
Binder
K.
,
1996
, “
Cooling-rate effects in amorphous silica: A computer-simulation study
”,
Phys. Rev. B
,
54
, pp.
15808
15827
.
This content is only available via PDF.
You do not currently have access to this content.