
147Femtosecond Laser-Induced Damage in Dielectric Materials
Chapter 5
of background organics, mostly aromatic compounds. Normally, these deposits are
removed by oxygen in the air when excited by the laser pulse.
It turns out that the fs LIDTs of oxide lms also change with ambient gas composition
and pressure (Nguyen et al. 2011), although for reasons dierent than those discussed
for ns pulse exposure. Figure 5.13 shows that the multiple-pulse damage uence in vac-
uum drops to about 10% of F
1
at atmospheric pressure. e single-pulse thresholds are
unaected by pressure, and there is little dierence in the F
th
(S) curves for S < 1000.
Together ...