Scanning near-field optical microscopy (SNOM) is used to study the photo-induced deformation of layered structures
containing azobenzene derivatives. This approach is particularly relevant since it allows detecting in real-time, with the
same probe the surface topography and the optical field distribution at the nanoscale. The correlation between the local
light pattern and the ongoing photo-induced deformation in azobenzene-containing thin films is directly evidenced for
different light polarization configurations. This unveils several fundamental photodeformation mechanisms, depending
not only on the light field properties, but also on the nature of the material. Controlling the projected electromagnetic
field distribution allows inscription of various patterns with a resolution at the diffraction limit, i.e. of a few hundreds of
nm. Surface relief patterns with characteristic sizes beyond the diffraction limit can also be produced by using the nearfield
probe to locally control the photo-mechanical process. Finally, the photo-mechanical properties of azo-materials are
exploited to optically patterned metal/dielectric hybrid structures. Gratings are inscribed this way on thin gold films. The
characteristic features (enhancement and localization) of the surface plasmons supported by these noble metal structures
are studied by near-field optical microscopy.
We present a study on erbium (Er)-doped silicon (Si)-rich silicon oxide thin films grown by the magnetron cosputtering of three confocal cathodes according to the deposition temperature and the annealing treatment. It is shown that, through a careful tuning of both deposition and annealing temperatures, it is possible to engineer the fraction of agglomerated Si that may play the role of sensitizer toward Er ions. To investigate the different emitting centers present within the films according to the fraction of agglomerated Si, a cathodoluminescence experiment was made. We observe in all samples contributions from point-defect centers due to some oxygen vacancies and generally known as silicon-oxygen deficient centers (SiODC), at around 450-500 nm. The behavior of such contributions suggests the possible occurrence of an energy transfer from the SiODCs toward Er3+ ions. Photoluminescence experiments were carried out to characterize the energy transfer from Si nanoclusters toward Er3+ ions with a nonresonant wavelength (476 nm) that is unable to excite SiODCs and then exclude any role of these centers in the energy transfer process for the PL experiments. Accordingly, it is shown that structural differences have some effects on the optical properties that lead to better performance for high-temperature deposited material. This aspect is illustrated by the Er-PL efficiency that is found higher for 500°C-deposited, when compared to that for RT-deposited sample. Finally, it is shown that the Er-PL efficiency is gradually increasing as a function of the fraction of agglomerated silicon.
We present a study on erbium-doped silicon rich silicon oxide (SRSO:Er) thin films grown by the magnetron cosputtering
of a three confocal cathodes according to the deposition temperature and the annealing treatment. It is shown
that several parameters such as the stoichiometry SiOx, the Erbium content and the fraction of agglomerated Silicon are
strongly influenced by the deposition temperature. Especially, an increase of the fraction of agglomerated-Si concomitant
to a reduction of the erbium content is observed when the deposition temperature is raised. These structural differences
have some repercussions on the optical properties that lead to better performances for high-temperature deposited
material. It is illustrated by the Er-PL efficiency that is higher for 500°C-deposited than for RT-deposited sample at all
annealing temperatures. Finally an investigation of the different emitting centres within the films is performed with a
cathodoluminescence technique to highlight the emission of optically-active defect centers in the matrix. It is shown that
some oxygen vacancies, namely Silicon-Oxygen Deficient Centers, have a strong contribution around 450-500 nm and
are suspected to contribute to the energy transfer towards Er3+ ions.