Planar TiO2 waveguides by the sol-gel process: the relationship of structure to properties

Mohammed Bahtat; Jacques Mugnier; Liren Lou; Jean Serughetti

doi:10.1117/12.132011

7 December 1992 Planar TiO₂ waveguides by the sol-gel process: the relationship of structure to properties

Mohammed Bahtat, Jacques Mugnier, Liren Lou, Jean Serughetti

Proceedings Volume 1758, Sol-Gel Optics II; (1992) https://doi.org/10.1117/12.132011
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

Recent works in our laboratories investigated the microstructure of titania films prepared from a colloidal solution and used as planar waveguides. The transmission electron microscopy including high resolution observations together with waveguide Raman spectroscopy, especially in the very low frequency range, showed a strong influence of the heat-treatment procedure on the films' morphology. In addition, atomic force microscopy provided valuable information on their surface roughness. At lower temperatures (450 degree(s)C), the films' structure consists of a mixture of amorphous TiO₂ and anatase nanocrystals (4.5 - 5 nm) and its surface is smooth. On the contrary, when increasing the annealing temperature, the nanocrystals grow (50 nm at 1000 degree(s)C), pores (5 - 20 nm) are clearly distinguished and the films' waveguiding properties disappear. Here, we discuss the optical behavior of these films and its relationship to microstructure. It is clearly shown that a high degree of crystallization induces an important porosity, a rough surface and thus dramatically affects the films' waveguiding properties. Finally, we report a relatively simple strategy to stabilize the amorphous phase and control the crystallization in order to improve the optical quality of the waveguides.

Citation Download Citation

Mohammed Bahtat, Jacques Mugnier, Liren Lou, and Jean Serughetti "Planar TiO₂ waveguides by the sol-gel process: the relationship of structure to properties", Proc. SPIE 1758, Sol-Gel Optics II, (7 December 1992); https://doi.org/10.1117/12.132011

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