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Electron beam irradiation of silica is a very flexible technique for the fabrication and trimming of optical circuits for the telecommunications and biosensing areas. In this paper, we review the effects induced by electron beam irradiation of germanium-doped, flame-hydrolysis deposited (FHD) silica. The structural modifications were studied with Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The compaction of the material was characterized by profilometry and the refractive index variation and index distribution of channel waveguides were characterized using the m-line technique and microreflectivity, respectively. Finally, some optical devices were fabricated using this technique with application in optical fluorescence sensing. The technique appears as a very interesting way of fabrication low-loss optical waveguides in silica. [ABSTRACT FROM PUBLISHER]

Genetic algorithms have been demonstrated to be a robust method for the calculation of the refractive-index profile of annealed germanium-doped flame-hydrolysis deposited (FHD) silica layers using measurements of the effective refractive indexes of the different modes of propagation. A nonuniform refractive-index profile in depth was obtained, which agrees well with the germanium concentration and density profiles measured for the films. [ABSTRACT FROM PUBLISHER]