Biomedical Engineering Reference
In-Depth Information
3.12
Spectral variation of the optical linear coefficients for Au:SiO
2
thin
film of thickness 100 nm and gold volume fraction of 0.2. (a) Refractive
index
.
3
n
. (b) Absorption coefficient
β
containing crystalline phases that exhibit second-order non-linear optical
properties, such as BaB
2
O
4
and LiNbO
3
.
31
Third-order non-linearity is also seen in ceramic nanocomposites. Debrus
et al.
3
studied the third-order non-linear optical properties of Au:SiO
2
thin
films at the surface plasmon resonance wavelength by the z-scan technique
using a nanosecond laser (Fig. 3.12). They prepared the films by multilayer
deposition using a sputtering technique. For a metal volume fraction equal
to
0.2,
they
obtained
a
very
large
negative
imaginary
part,
10
6
esu, which is characteristic of an absorption
saturation. The non-linear absorption coefficient
χ
eff
(3)
=
Im
3.0
6
β
was found to be negative
10
6
cm/W.
and equal to 1.1
6
3.5
Luminescence
Luminescence is another important property of nanoparticles and its
primary application is in medical, biological or pharmaceutical areas.
Semiconducting nanoparticles are currently the most important luminescent
