| Abstract
| - Photosensitive Ce3+-doped aluminosilicate planar waveguides have been prepared by a sol−gel process. Thewaveguides, which have been characterized using different techniques, appear to be totally amorphous andof good optical quality. The m-lines technique and waveguide Raman spectroscopy have shown that thedoping of the guides with Ce3+ ions slows the densification process and that consequently the effect of dopinghas to be taken into account for the characterization of such materials. X-ray photoelectron spectroscopy(XPS) analysis of the samples has revealed a very high concentration of nonbridging oxygens (NBO) at thesurface. To study the mechanisms responsible for the photosensitivity of these waveguides, selected sampleshave been hydrogenated and irradiated with UV light and then analyzed by XPS. Results have shown astrong decrease of the O/(Al + Si) atomic ratio, especially at the surface of these guides, after H2 loading andUV irradiation. This decrease is correlated with the high concentration of NBO at the surface of the samplesand has been interpreted as resulting from the formation of molecular water accompanied by the creation ofdefects in the glass.
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