Analysis of self-written waveguide experiments

Three aspects of the experimental observation of self-written waveguides are analyzed. The evolution of the self-written waveguide is compared quantitatively with a model that incorporates saturation and an exposure-dependent attenuation, giving excellent agreement. The spatial features of the self-written channel that are observable by luminescence are qualitatively explained by the same model. Even though the channel is multimoded at the blue writing wavelength, it is demonstrated to be single moded at the wavelength $\mathrm{\lambda }=1550 \mathrm{nm},$ consistent with predictions.