Photosensitivity of Sol-Gel derived Aluminosilicate Planar Waveguides doped with Ce³⁺ ions.
by J.M. Nedelec S. Turrell, M. Douay and M. Bouazaoui

Aluminosilicate planar waveguides doped with Ce³⁺ ions have been prepared by combining a sol gel process and the dip-coating technique. The sol-gel process has been proven to be a convenient method to prepare good optical quality homogeneous amorphous waveguides doped with rare earth ions. For the first time to our knowledge, the photosensitivity of these materials has then been studied. Experiments performed on these samples demonstrated their potentiality to be used as photorefractive materials for integrated optical devices. We have shown that hydrogenation of the samples is a necessary condition for writing gratings. High fluence inscription leads to the photoablation of the film but low fluence experiments allow the inscription of index grating with Dn=5.10^-4. Diffraction efficiency of the gratings versus Ce³⁺ content with or without hydrogenation are shown below.

Diffraction efficiency h for the different samples

Moreover, the accurate control of the chemical parameters of the preparation of the waveguides via sol-gel chemistry will allow us to study the effect of each parameter (Al/Si ratio, Ce³⁺ concentration, annealing temperature, hydrogenation treatment, etc...) on the photorefractivity of the materials and thus lead to a better understanding of the mechanisms responsible for the observed photorefractivity. An XPS study has been worked out to understand the basic mechanism of this photosensitivity and can be found in J. Phys. Chem. B 104 (2000) 926.

More about this work : Journal of Sol-Gel Science Vol 20, N°3, 2001, 287

For more information contact: 

Jean-Marie Nedelec (solgel.com editor)
Laboratoire des Matériaux Inorganiques,
CNRS UMR 6002, Université Blaise Pascal et Ecole Nationale Supérieure de Chimie de Clermont-Ferrand,
63177 Aubière cedex, France
E-Mail : jnedelec@chimtp.univ-bpclermont.fr