Attenuation in planar optical waveguides: Comparison of theory and experiment

Experimental measurements of the guided-wave attenuation and surface roughness for three Corning 7059 glass waveguides were compared to the predictions of a surface-scattering theory. The attenuation coefficient was calculated by means of a first-order boundary-perturbation theory, and was used to examine the role of the various parameters in determining guided-wave attenuation. The comparison to experiment shows that the measured level of surface roughness is insufficient to account for the measured TE
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attenuation, a fact that suggests that scattering by refractive-index fluctuations in the volume of these waveguides dominates.