II- Investigations of the Formation of Holographic Diffraction Gratings .

Following the pioneering work of Natansohn and Tripathy, high efficiency diffraction gratings are inscribed by one-step holographic polarization recording on azopolymers thin films. These surface relief gratings (SRGs) are stable at room temperature and no wet or photocuring steps are necessary. Our approach consists in developing optical and spectroscopic methods with the aims to:
    (i) Analyse the dynamic of formation and polarization properties of the gratings together with theoretical approach and polarimetric experiments.
    (ii)Determine the molecular orientations with advanced microscopy techniques such as Raman confocal microscopy.
    (iii)Fabricate complex mesostructures with new properties such as nonlinear optical diffraction gratings. Characterization is done by AFM, SHG-NSOM and far field nonlinear measurements.
    (iv)Design surface relief structures to align molecules or nanostructures of interest (colloids, nanotubes, etc…)

Exemple of a complex grating inscribed on a functionalized polymer
AFM imaging of two superimposed diffraction gratings.