Selective buried waveguides have different regions, lying at various depths under the glass surface. This structure is formed by field-assisted inter-diffusion in an electrically inhomogeneous glass, with an electrical conductivity varying both spatially and in time. We present a simple, preliminary model of such a complex, two-dimensional structure. We explain the assumptions used to obtain a tractable model and discuss them in detail. Our results are illustrated by mono- mode structures, buried under normal electric field intensities. They are in qualitative agreement with experimental measurements. We discuss the improvements of the model, necessary to take into account spatial and temporal variations of glass properties.
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