dc.description.abstract | We performed ablation on both an air-water interface and a gold-silica-air interface.
Pulses with a duration of 160 fs were shot at the materials, with fluences ranging
from 0.2 mJ cm^-2 up to 0.35 J cm^- 2 . This was done to study the self-reflectivity.
According to existing theory the reflectivity of water should not significantly
change in this fluence regime. We measure however an increase of 0.0023, around
a fluence of 1 mJ cm ^-2 , after which the reflectivity stays at this constant at the
higher value.
When performing the measurement on the gold with a thin nano-layer of silica,
we witness ablation at fluences around the ablation threshold of gold, but far
below that of silica. The addition of a thin layer of silica decreases the addition
with approximately 40%. Increasing the thickness of the layer will lead to an
increase again of the ablation threshold.
The self-reflectivity of the samples resemble those of gold, but see a steeper
decline. We developed a simple model, assuming no non-linear behaviour of the
silica. We will present evidence suggesting penetration of hot electrons from the
gold in the silica. | |
dc.subject.keywords | Optics, Laser physics, Laser Ablation, Ultrafast Dynamics, Self-reflectivity, Femtosecond, Nanolayer, Nanotechnology, Micro-machining, Pulsed laser, Photonics, Nanophotonics, Gold, Silica, Water, Non-linear optics, Drude model, refractive index, Ablation Threshold | |