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Erbium-doped tellurite glasses are of great interest for the fabrication of active integrated circuits because of their unique properties in terms of bandwidth and rare earth solubility. The fabrication of multimode channel waveguides in a glass of this family, namely, a sodium-tungsten-tellurite glass, is demonstrated using a high-energy ion beam irradiation technique. Nitrogen ions with dose of 1.0×1016ions∕cm2 and 1.5MeV energy were used for this aim. The waveguiding effect was investigated using the end-fire coupling technique.

Polysilicon layers with thicknesses between 8 and 600 nm deposited by low-pressure chemical vapor deposition at temperatures ranging from 560 to 640°C were characterized by spectroscopic ellipsometry ͑SE͒ to determine the layer thicknesses and compositions using multilayer optical models and the Bruggeman effective-medium approximation. The dependence of the structural parameters on the layer thickness and deposition temperature have been investigated. A better characterization of the polysilicon layer is achieved by using the reference data of fine-grained polysilicon in the optical model. The amount of voids in the polysilicon layer was independently measured by Rutherford backscattering spectrometry ͑RBS͒. The SE and RBS results show a good correlation. The comparison of the surface roughness measured by SE and atomic force microscopy ͑AFM͒ shows that independently of the AFM window sizes, a good correlation of the roughness determined by SE and AFM was obtained.

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