ABSTRACT
A number of distinctive features of ultra-short lasers interaction with mat-
ter have attracted several specific applications, which are described below.
First feature to be mentioned is the ability to control the phase state of ab-
lated vapours through the optimum pulse and focusing conditions adjusted
to the ablated material properties. This feature ensured the application of
ultra-short lasers for the ablation of different materials with the subsequent
condensation of ablated plume on a substrate for producing the thin films
of superb quality. The ablation of solids by powerful lasers of differ-
ent pulse duration has attracted a significant attention during the past
decades due to many potential applications of this effect in industry, medi-
cine, material science and technology. However, pulsed laser deposition
(PLD) when applied in its conventional form using low-repetition rate lasers
emitting nanosecond-range pulses [Chrisey and Hubler, 1994, Miller and
Haglund, 1998] generally leads to poor quality films contaminated by par-
ticles. It has been shown that this disadvantage of conventional PLD is
a direct consequence of the ablation regime due to the far from the op-
timum laser parameters [Gamaly et al., 1999; Rode et al., 1999]. The
plume produced in long-pulse regime expands as a super-saturated vapour
and therefore condensation occurs during the early stage of the expan-
sion resulting in the formation of droplets from the vapour phase, that
are then deposited onto the substrate. It has been shown in Chapter 4
that the ablated plume can be kept in atomised state during the expan-
sion stage through the proper choice of pulse duration, wavelength and
energy along with a proper spatial and temporal distribution of the laser
intensity during the pulse time and across the focal spot keeping the ab-
sorbed laser energy above some specific threshold. The experimental imple-
mentation of these recipes for deposition of different materials is presented
later in this section.
