Magneto-optics and nanophotonics offer promising developments for applications in various technological sectors like
data manipulation and storage, bio-imaging or optical sensors. Towards such purposes we show that it is advantageous to
combine ultrafast magnetism performed with ultrashort laser pulses together with nanophotonics performed on various
magnetic materials. Firstly, we discuss the important physical mechanisms underlying the control of magneto-optical
nanodevices with femtosecond laser pulses. Secondly, we give examples of magneto-optical patterning which can be
used for switching or for realizing diffractive magneto-optics. For example, individual ferromagnetic CoPt3 dots can be
manipulated at the femtosecond time scale using confocal magneto-optical Kerr microscopy. Alternatively one can
pattern such dots and control their size and shape. Patterning magnetic arrays on ferromagnetic metals with light pulses
is also potentially very attractive for diffractive structures. Thirdly, we describe the advantages of performing coherent
magneto-optics. In particular, transparent magnetic materials like Garnets are well adapted for making self diffractive
Optical density measurement is a very powerful tool to characterize particle size and physical property of scattering
media such as sprays and engine injection. The major difficulty of such a measurement is the tremendous amount of
scattered light: for such media, the optical density can be greater than 10. The goal of this work is to develop a new
experimental tool, based on femtosecond laser technology in order to isolate (spatially and temporally) a very limited
amount of non scattered transmitted light, and to measure the extinction of the media.
We collect the transmitted light and we use an optical Kerr gating. This technique is very powerful to determine the time
of flight of every photon in the scattering media. By fine-tuning the optical parameter of the setup, we have been able to
selectively increase the gating efficiency of the ballistic part vs the diffusive part of the collected light.
Furthermore, spectral tunability of amplified femtosecond laser system is straightforward. As a result, it has been
possible to measure the extinction spectra of a model diffused media (SiO2 particle in water), and to determine the
particle size distribution after inversion method.
The aim of this work is to contribute to a better determination of the optical parameters for dense scattering media. We
study the interaction of femtosecond polarized light pulse with a scattering medium considering Monte Carlo simulation.
The Monte Carlo scheme is based on temporal photon tracking, including a pseudo Monte Carlo approximation
associated to two small detectors in forward and backward directions. The statistical scattering properties are derived
from temporal phase matrices, which are evaluated through a scanning of frequency associated to the Lorenz-Mie theory.
We specially focused our attention on solid rocket motor modelling. In such scattering medium, large optical thickness,
various bimodal particle size distributions and concentration gradients could be observed. Moreover, such media consists
in a suspension of big particles (typically 100 &mgr;m diameter). The understanding of the scattering process of such particles
needs the introduction of Debye modes. We will explain the contribution of these modes and give an example with a